Papers for Tuesday, Apr 21 2026

The VASCO project has identified over 100,000 optical transients on photographic plates from the First Palomar Observatory Sky Survey (POSS-I, 1949-1957). Cann (2026a) demonstrated a dose-dependent suppression of transient detection rates across five geomagnetic storm intensity (Kp) bins (Cochran-Armitage: Z = -3.391, p = 0.0007, 3.4 sigma). A principal objection to this finding is that geomagnetic storms enhance atmospheric airglow, reducing overall plate sensitivity and thus suppressing detection of all sources, not just transients. We test this artifact hypothesis directly using the Minnesota Automated Plate Scanner (MAPS) Catalog of the POSS-I archive, which records stellar detection counts (NSTARS) for each of 638 fields with precise observation dates. Cross-referencing NSTARS against the GFZ Potsdam Kp archive reveals no significant trend across five Kp intensity bins (Spearman rho = 0.017, p = 0.673, 0.4 sigma), in sharp contrast to the transient suppression established in Cann (2026a). Geomagnetic storms suppress transient detections dose-dependently while leaving stellar detection counts unchanged. The plate sensitivity artifact hypothesis is ruled out. Combined with four independent lines of evidence, the overall significance of the transient phenomenon reaches 4.9-5.5 sigma (Fisher's method).

Higher derivative quantum corrections are essential components of scalar tensor effective field theories (EFTs), yet they typically reintroduce the Ostrogradsky ghost instability that the classical theory was designed to evade. This paper resolves this fundamental tension by establishing a rigorous equivalence between two distinct criteria for theoretical consistency. We analyze a general DHOST theory augmented by Gauss Bonnet and Weyl squared operators with coefficients that are arbitrary functions of the scalar field and its kinetic term. We then pursue two independent paths: first, we derive a set of differential equations for these coefficients by demanding that the full action remains invariant under the protective gauge symmetry of the classical theory. Second, we perform a first principles Hamiltonian analysis using the ADM formalism, deriving a separate set of conditions by imposing the primary and secondary constraints required to eliminate the ghost. Our central result is the proof that these two sets of conditions, one algebraic and one dynamical, are mathematically identical. This equivalence demonstrates that the gauge symmetry is the fundamental origin of Hamiltonian stability in the quantum corrected theory and establishes the symmetry principle as a powerful and practical tool for constructing consistent, ghost free gravitational EFTs without resorting to a full Hamiltonian analysis

The possibility of over-massive black holes suggested by James Webb Space Telescope photometric discoveries of 'little red dots', may disfavor light supermassive black hole (SMBH) seeds. However, what should constitute the mass (range) of 'heavy' seeds remains relatively unconstrained. Moreover, Vera C Rubin Observatory's Legacy Survey of Space and Time will photometrically characterize galaxies without direct black hole mass measurements. We forward-model the SIMBA, IllustrisTNG, and EAGLE cosmological simulations into the photometric bands of LSST to train an ensemble machine learning classifier. Our framework achieves $91\%$--$94\%$ accuracy across SIMBA and IllustrisTNG in distinguishing between over-massive and under-massive SMBH growth regimes under LSST magnitude limits, using only broadband photometry. Furthermore, cross-simulation transfer experiments (training on one cosmological simulation and evaluating on another using rank-normalized features) achieve $83\%$--$89\%$ accuracy. This suggests the relative photometric ordering of growth regimes is largely preserved even across fundamentally different sub-grid SMBH feedback prescriptions. Signal decomposition shows our classification is driven by host galaxy colors ($82\%$--$87\%$ accuracy) and, relatedly, the accretion-state's spectral energy distribution shape as opposed to an inversion of our forward model's analytical luminosity prescription. Given that the evaluated simulations employ heavy seed prescriptions ($\geq 10^{4}~M_\odot$), our methodology establishes a validated baseline for classifying post-seeding growth regimes.

Accurate sky localization is essential for gravitational-wave (GW) astronomy, particularly for multimessenger follow-up and host galaxy identification. For strongly lensed GW events, achieving localization at the level of $\sim 10~\mathrm{deg}^2$ is critical for associating signals with their lensing structures and enabling targeted searches for additional faint images. We investigate how sky localization improves when combining multiple lensed images of the same source. Using simulated lensed compact binary coalescences and \textsc{BAYESTAR} sky localization, we evaluate localization performance as a function of image multiplicity. We find that combining multiple images leads to a systematic improvement in localization, with the largest gain occurring when combining two images, typically reducing the 90\% credible region area by an order of magnitude. Additional images provide further improvements, with four-image systems achieving localization areas of $\sim 10$--$100~\mathrm{deg}^2$. We also show that subthreshold images contribute modest but non-degrading improvements, enabling their safe inclusion in localization analyses. These results demonstrate that strongly lensed GW events provide a natural pathway to improved localization and motivate hierarchical search strategies for detecting faint lensed images.

Superluminous supernovae (SLSNe) are among the most energetic stellar explosions, yet their central power source remains uncertain. Models invoking magnetar spin-down or circumstellar interaction predict GeV gamma-ray emission once the ejecta becomes transparent to high-energy photons. We search for such emission from 223 hydrogen-poor SLSNe using 17 years of Fermi-LAT data, defining source-specific search windows based on the Bethe--Heitler transparency time. We find no significant ($\geq5\sigma$) GeV emission. A joint-likelihood analysis constrains the GeV-to-optical efficiency to $\eta < 1.3\times10^{-3}$, two orders of magnitude below the predictions for weakly magnetized magnetar nebulae. A hierarchical population analysis shows that fewer than $0.7\%$ of SLSNe-I can have $\eta > 10^{-2}$. SN 2017egm, however, shows a suggestive excess ($\sim$4 $\sigma$). In the 0.1--500 GeV band, the observed $L_\gamma/L_{\rm opt} \sim 0.68$ for SN 2017egm exceeds hadronic expectations by over an order of magnitude, favoring a magnetar origin. The non-detection of the similarly nearby SN 2018bsz disfavors simple uniform-efficiency scenarios, or potentially points to diversity in the underlying powering mechanisms. We also note a possible excess from SN 2024jlc, though continued Fermi-LAT monitoring is needed because the source may still be within its transparency window.

Correlations between standardized Type Ia supernova (SN Ia) luminosities and host-galaxy properties are routinely modeled to avoid bias in cosmological parameter inference. A recent hypothesis attributes these correlations to progenitor-age variations and, combined with a strong ($\sim$5-6 Gyr) age evolution between low- and high-redshift samples, could alter cosmological conclusions. We test this scenario using the SN Ia host galaxies of TITAN DR1, the largest low-redshift sample of its kind to date (6,983 hosts; 0 $\lesssim$ z $\lesssim$ 0.15). Progenitor ages are estimated by combining host-galaxy star-formation histories (SFHs) with empirical delay-time distributions. The SFHs are constrained via spectral energy distribution (SED) fitting of photometry spanning ultraviolet (UV) to mid-infrared (MIR) wavelengths, enabling robust separation of dusty star-forming and quiescent systems. The resulting progenitor-age distribution has a mean of 3.5 Gyr, substantially younger than predicted by strong-evolution models. It is strongly peaked near 2.2 Gyr, predominantly from star-forming hosts (60% of the sample), with a smaller, broader component centered near 6.0 Gyr from quiescent systems. Restricting to high-mass galaxies (in order to isolate progenitor effects from the mass-step), the age difference between host types reduces to 3.3 Gyr which, under the age-dependence hypothesis, would imply a 0.10 mag luminosity offset, inconsistent with observed standardized magnitudes. We infer a modest 1.5 Gyr evolution in mean progenitor age over cosmic time which, combined with observed age-Hubble-residual (HR) relations, yields a maximum redshift-dependent bias of $\Delta$HR = $-0.007^{+0.012}_{-0.014}$ mag, consistent with zero. We find no evidence for a large, unmodeled progenitor-age systematic beyond what is already captured, to good approximation, by standard host-mass corrections.

We predict the primordial deuterium abundance using a novel, fully data-driven approach, where we use Gaussian process regression to fit experimental nuclear reaction data for $d$,($d$,$n$)$^3$He, $d$,($d$,$p$)$t$, and $d$($p$,$\gamma$)$^3$He, three reactions to which the primordial deuterium abundance is most sensitive. Using the Planck determination of the baryon density, we predict $10^5\times\mathrm{D/H} = 2.442\pm0.040$ in standard Big Bang Nucleosynthesis, $1.70\sigma$ below the Cooke et al. measurement. Our result is consistent with predictions relying on first principles calculations of the deuterium burning cross sections. With the inferred baryon density from a combined fit to Planck, ACT DR6, and SPT-3G D1, this discrepancy worsens to $1.98\sigma$. We validate our approach and confirm that Gaussian processes make unbiased D/H predictions with appropriately-sized uncertainties. We repeat our validation tests for low-degree polynomial fits, a technique used in previous analyses, and find that they systematically over-predict D/H. Our results highlight the need for improved measurements of the $d$,($d$,$n$)$^3$He and $d$,($d$,$p$)$t$ S-factors at energies between 0.1 and 0.6 MeV.

The so-called 'Galactic Center' Lobe (GCL) is an extended (~1 deg) radio continuum feature situated above the Galactic Plane, for which the literature contains varying claims about both its nature and location. Using new optical integral field spectroscopic observations from the SDSS-V Local Volume Mapper, we confirm the characterization of the GCL as a foreground photoionized HII region, not associated with the Galactic center. We present a new analysis of the ionized gas morphology, line ratio diagnostics, and kinematics. From our [SIII]9532 emission line map, which suffers the least extinction, we identify ionized gas emission throughout a closed outer loop, which does not fill the GCL interior. All optical line ratio diagnostics are consistent with photoionization. By comparing the ionized gas reddening from the Balmer decrement with 3D dust maps, we directly constrain the distance to the GCL to ~2 kpc. [NII]6583 line kinematics show a uniform velocity structure across the GCL, further confirming that the entire bubble is one structure. The size and emission line morphology is strongly reminiscent of that seen in the nearby Barnard's Loop, providing a possible analog to explain how this outer shell may be photoionized by a more distant and off-center embedded young cluster. We suggest the acronym GCL be repurposed to instead abbreviate the name 'Greatly Confused Loop'.

Carbonaceous chondrites are samples from planetesimals that formed 2-4 million years after solar system formation began. They consist of distinct dust components formed at different times and locations in the accretion disk and whose abundances in carbonaceous chondrites vary over planetesimal formation time. The mechanism that led to this time-varied accretion is not understood, but is critical for understanding late-stage planetesimal formation. Using a two-dimensional Monte Carlo simulation of dust evolution, we show that differences in dust filtering and delivery rates of distinct dust components to a planet-induced pressure bump in the disk reproduce the observed compositions and formation ages of the carbonaceous chondrites. This implies that carbonaceous chondrites likely formed in a single, long-lived dust trap, most likely outside of Jupiter's orbit. Because differentiated meteorites, which sample an earlier generation of planetesimals, exhibit similar isotopic variability as the chondrites, they likely have also formed in dust traps, implying these structures were the dominant site for planetesimal formation in the solar system.

The general relativistic magnetohydrodynamic (GRMHD) simulations are widely used to study accretion disk and jet dynamics around a black hole. Despite strong observational evidences for intrinsically nonlinear behavior, the interpretations of GRMHD simulation results, more precisely the underlying timeseries, have not been well-explored by nonlinear timeseries analysis. In this work, we characterize the jet and disk dynamics of different GRMHD simulated flows using the nonlinear timeseries analysis. As diagnostic tools, we consider Higuchi fractal dimension (HFD), Hurst Index (H) and spectral slope. We implement them for two model disk frameworks: magnetically arrested disk (MAD) and standard and normal evolution (SANE), across a range of black hole spins with the Kerr parameter spanning from -0.9375 to 0.9375. We simulate the disk/jet systems by two well-documented codes: HARMPI and BHAC, and obtain, respectively, low and high temporally resolved timeseries data. For both jet and disk dynamics, MADs are characterized by higher HFD, lower H and flatter spectral slopes than SANEs. High HFD in MAD could be due to its intermittent variability and indicates that it has lesser long-range temporal correlations than SANE. Moreover, HFD in MAD decreases with spin magnitude owing to increase in collimated, hence ordered, jets. However, in SANE, it increases with spin for positive ones due to interplay of winds and jets. Extending our analysis to observations, we attempt to segregate the classes of black hole: GRS 1915+105, into MAD- and SANE-like clusters based on their spectral properties extracted from X-ray data. The mean HFD of MAD-like cluster is higher than SANE-like cluster, thus, corroborating with the simulation results. Our work highlights the role of nonlinear timeseries analysis to understand the underlying dynamics of accretion flows and their connection to magnetic regulation.

The stability and longevity of globular clusters (GCs) make them effective tracers of the dynamical histories of galaxies in cluster environments. We construct a catalog of 23,351 GC candidates in the Coma cluster using imaging from the Hubble Space Telescope Advanced Camera for Surveys. We cross-match galaxy data from the SIMBAD, NED, and SDSS archives to construct a galaxy sample and model their GC populations using the GC specific frequency. We find several galaxies with significantly smaller GC populations than expected from their luminosities, consistent with either tidal stripping or intrinsically low formation efficiencies. We analyze annular and Voronoi GC radial profiles of the BCGs (NGC 4874 and NGC 4889) and other Coma galaxies. A 2D Voronoi density mapping reveals GC populations with marked deficits compared to our modeled expectations, including galaxies in proximity to the BCGs (e.g., IC 3998, NGC 4875, NGC 4876) and others distributed across Coma (e.g., NGC~4908, NGC~4883, IC~4042). Azimuthal symmetry testing suggests past dynamical interactions may have truncated GC systems in some galaxies, while intrinsic deficits are probable in others (e.g., IC 3973, IC 3976, IC 4040, IC 4045). Our results show that GC deficits exist in several Coma galaxies and that the 2D density structure reveals environmental signatures, with asymmetry statistics consistent with directional stripping. These findings highlight GC populations as powerful probes of environmental processing and the dynamical histories of galaxies in dense cluster environments.

In this work, we present a cosmological model in which the cosmological constant term is replaced by the Kretschmann scalar at the level of the action. In this way, it becomes possible to implement a model of dynamical dark energy. After constraining the free parameters using observational data from supernovae and cosmic chronometers, we show that the model provides a good fit to the observational data. In particular, we show that, at least at low redshifts, the behavior of the equation-of-state parameter $w(z)$ closely reproduces that obtained in phenomenological models that have been recently studied based on the latest observational data from the DESI collaboration. Likewise, the present model also indicates the occurrence of a phantom-crossing regime.

Here we present models of hot neutron star (NS) atmospheres consisting of thermonuclear ashes of various chemical compositions. These models are essential for studying thermonuclear flashes in X-ray bursting NSs in which nuclear-burning ashes are transported to the stellar surface. We consider four different mixtures, each dominated by helium, chromium, iron, or nickel. In addition to the opacity sources previously used in NS atmosphere modeling, we include photoionization from excited ionic states as well as approximately 5000 spectral lines. We also develop a method that enables the simultaneous treatment of Compton scattering and a large number of spectral lines. A key feature of the modeled NS atmospheres is the presence of a layer in the transition region between the optically thin and optically thick parts of the atmosphere where the radiation-pressure force increases significantly. This enhanced force sets an upper limit on the maximum attainable bolometric flux for a given surface gravity and chemical composition. The emergent spectra from the computed atmospheres display pronounced absorption edges, whose energies are determined by the dominant chemical species. We fit the model spectra using a diluted blackbody modified by a single absorption edge, and we investigate how the fit parameters depend on both the relative bolometric flux and the chemical composition of the atmosphere. Finally, we discuss constraints on these models imposed by the properties of X-ray bursts that exhibit absorption edges in their spectra, as observed in the systems HETE~J1900.1$-$2455 and GRS~1747$-$312.

We present a new determination of the evolving galaxy UV luminosity function (LF) over the extreme redshift range $12.5<z<18.5$, based on a wide-area search of $>$0.6 deg$^2$ of JWST NIRCam imaging containing $>150$ independent sight-lines. We find evidence for an accelerated decline in the UV LF, and hence inferred star-formation rate density ($\rho_{\rm SFR}$), over the $\simeq100\rm{Myr}$ cosmic time interval between $z=11$ and $z=13.5$. Moreover, based on a notable lack of galaxy candidates at $z>14.5$, we find evidence for an even more rapid descent in star-formation activity towards earlier times, with our new measurement of $\rho_{\rm SFR}$ at $z\simeq15.5$ lying significantly below an extrapolation of the log-linear $\rho_{\rm SFR}(\rm z)$ relation inferred from early JWST LF studies. Instead, we find that the evolution in $\rho_{\rm SFR}(\rm z)$ at these very early times is better described by a piece-wise log-linear relation, in which the decline in $\rho_{\rm SFR} (\rm z)$ at $z>12$ is $\simeq4$ times steeper than at redshifts $z < 12$. Our observational results are consistent with a number of theoretical models of galaxy evolution which have incorporated a range of treatments in an attempt to explain the prevalence of UV-bright galaxies at least out to $z \simeq 12$ (e.g., increased star-formation efficiency, stochastic star-formation histories, an evolving stellar initial mass function and/or a shift towards attenuation-free stellar populations). However, our results are also entirely consistent with a relatively simple galaxy evolution model with no such adjustments, in which the rapid evolution of the dark-matter halo mass function at early times is for a while partially masked by progressively younger stellar ages, with the inferred epoch of first galaxy formation lying at $z\simeq15$.

1ES 1927+654 is an extreme active galactic nucleus (AGN) that has defied our canonical expectations for how AGN appear across the electromagnetic spectrum and how they vary on short timescales. In 2022, this source began showing a X-ray quasi-periodic oscillation (QPO) at mHz frequencies, along with a newly launched radio jet. Unlike the handful of other known AGN QPOs, the QPO in 1ES 1927+654 showed a significant frequency evolution, spanning from 0.9-2.4 mHz from 2022-2024. In this work, we present the last 1.5 years of monitoring with XMM-Newton (250 ks) up to January 2026, which reveals that the QPO persists but has plateaued at a constant frequency of approximately 2.5 mHz. We perform detailed spectral-timing analyses on this exquisite dataset, consisting of over 900 QPO cycles, more than any AGN QPO to date. Our main findings are: (1) the stacked XMM-Newton power spectra shows no significant second harmonic, (2) a soft (reverberation-like) lag is observed at all frequencies and remains remarkably stable even as the QPO frequency evolved from 2022-2024, and (3) extreme X-ray jumps on the QPO period (up to ~80% baseline flux) persist to present day with a remarkably stable dip-rise-fall pattern. Finally, we also detect the first AGN QPO in NuSTAR observations, which is present from 2023 to 2026 at frequencies consistent with the XMM-Newton detections. While we explore models for eclipses and coupled disk-corona behavior to simultaneously explain the lags, dips, and QPO, these new observations strain such models.

We study the metallicity distribution along the Sagittarius (Sgr) stream using photometric metallicities from S-PLUS DR4, combined with Gaia DR3 kinematics and APOGEE DR17 spectroscopy. Our analysis confirms that the leading arm (Galactic latitude $b > 0$) is systematically more metal-poor than the trailing arm ($b < 0$) by 0.15--0.20 dex, and reveals a clear negative metallicity gradient along the leading arm. The trailing arm shows no significant overall gradient but displays distinct inner (negative) and outer (positive) trends. These features are consistently recovered across different photometric estimators and agree with spectroscopic data. We compare these results with predictions from an $N$-body simulation, in which metallicities were assigned according to a set of imprinted radial gradients in the progenitor. We were able to constrain the original metallicity gradient of the Sgr progenitor to be between $-0.38$ and $-0.24$ dex kpc$^{-1}$ based on photometric data, and $-0.42$ to $-0.10$ dex kpc$^{-1}$ from APOGEE. These values are consistent with gradients observed in other Local Group dwarf galaxies. Our findings demonstrate that metallicity-sensitive photometric surveys such as S-PLUS are powerful tools for reconstructing the chemodynamical evolution of disrupted satellites.

The study of faint solar system objects is a promising avenue for understanding the origin and evolution of planetary systems. However, such objects are difficult to detect in conventional surveys. Here we introduce heliostack, an algorithm for nonlinear shift-and-stack searches for solar system objects, which enables us to combine images taken over longer time spans than was previously possible. Applying this algorithm to a number of existing archival and forthcoming surveys will allow us to maximize their potential for discovering faint solar system objects. In this work, we apply heliostack to archival Hubble Space Telescope (HST) data, completing an exhaustive search for Cold Classical Kuiper Belt Objects in a set of HST images taken over a 15-day time span in 2003. We successfully recover both of the known sub-threshold objects in the data, and add two new discoveries. These two new objects are the first to ever be discovered in stacks of images taken over a time span longer than about one day.

The primary mission of the Habitable World Observatory (HWO) will be to constrain the prevalence of life on Earth-like planets. These planets will be subject to impacts by energetic particles generated from coronal mass ejection (CME) shocks that can dramatically deplete ozone, a key biosignature gas. Other biosignatures are also likely vulnerable, though not yet studied. Here, we make a conceptual case for factoring sensitivity to stellar coronal mass ejections into the design of HWO. We drive design considerations by requiring that HWO constrain the rate of CMEs producing 10% or greater depletions of total ozone column to fewer than one per decade, the timescale over which ozone returns to pre-event levels. As CME detection methods, we consider coronal dimming, doppler shifted emission, high contrast imaging, and planetary aurora. We explore coronal dimming most thoroughly of the four, though with appropriate design considerations each of these may be possible with HWO.

Damped Ly$\alpha$ absorbers (DLAs) are the highest \HI\ column density (\NHI) absorption line systems detected in the spectra of background quasars. DLAs dominate the neutral gas content of the Universe ($\Omega_{\rm HI}$) and are used to measure the metallicity evolution of \HI\ gas. In this work, we introduce a sample of five recently detected DLAs at $z > 4.7$, found in mid to high-resolution spectroscopy from VLT/X-shooter and Keck/HIRES. These DLAs were not pre-selected based on metallicity, enabling an unbiased study of the metallicity of HI gas at $z \sim 5$. We also search for DLAs unbiased in metallicity at $0<z<5.5$ from the literature, we apply a combined correction for dust depletion and $\alpha$-enhancement (assuming no depletion of S, Si, and Zn) to Fe abundances, and we measure the cosmic metallicity evolution of $\alpha$-elements using a linear fit with a slope of$-0.22 \pm 0.05$ dex per unit redshift. For the highest redshift bin, we find an \NHI weighted average of $\langle Z \rangle = -2.00$. This value is $4.4\sigma$ deviant from the trend recovered at $z < 4.7$ and a K-S test comparison gives a $2.4 \sigma$ difference. We conclude that the metallicity of HI gas sharply decreases at $z \sim 5$, in agreement with previous tentative evidence. This sharp decrease may be connected with the onset of the enrichment of galaxies' circumgalactic media or with the end of cosmic reionization, though we cannot exclude that it is driven by small sample statistics.

The Vela supernova remnant (SNR), G263.9-3.3, and its pulsar wind nebula (PWN), Vela X, is one of the closest such systems, and it has been studied using observations across the electromagnetic spectrum. SNRs are known sources of gamma rays with energies from GeV to the TeV range. In the GeV band, a cluster of cataloged unidentified Fermi-LAT point sources are found across the large angular extension of the Vela SNR. We aim to search for a high-energy signature associated to the SNR. We applied two independent machine learning algorithms to classify unidentified point sources in the Vela region by comparing their properties to those of known populations of Fermi pulsars and active galactic nuclei. We analyzed LAT data and modeled the spectrum of any emission attributable to Vela using leptonic and hadronic processes typical of SNRs. We find that most of the "point sources" cataloged within the extent of Vela do not share characteristics with those of the two most common Fermi point-like source populations and that even after the emission attributed to these "point sources" is subtracted, considerable residual emission is seen throughout Vela. Morphologically, most of the GeV emission is found within the shell of the SNR. We conclude that the majority of the cataloged point sources are likely spurious, and the GeV gamma rays come from an extended source, which we argue is the counterpart of the Vela SNR. Adopting a simple morphology given by a uniform disk for the emission the resulting extension is 6.5 deg. The northeastern portion of G263.9-3.3, where the ambient density is thought to be higher, is brighter in gamma rays than the south and west. The spectrum of the emission is best fit with a hadronic model. These facts make the hadronic origin for the gamma rays more likely.

External interactions drive galaxy stellar mass growth and morphological evolution. As stellar haloes-assembled largely via hierarchical accretion-preserve signatures of these processes, their growth probes how environment regulates galaxy evolution. We investigate how cluster environments influence quiescent galaxy (QG) stellar halo assembly over 0.1 $\leq$ $z$ $\leq$ 1.0 in a sample of 2,168 cluster and 94,479 field QGs of $\log M_{\star} \geq 9.66$. Extended emission is traced via rest-frame $g$-band surface brightness ($\mu_g$) profiles extracted from deep HSC-SSP $grizy$ imaging. We study stellar halo assembly trends by linking median $\mu_g$ profile evolution to the underlying mass growth in galaxy subpopulations. Over 0.1 $\leq$ $z$ $\leq$ 1.0, cluster QGs build up stellar haloes faster than field QGs, with a $\sim23\%$ and $\sim40\%$ larger increase in integrated stellar halo luminosity ($L_{halo}$) in the low-mass ($9.66 \leq \log M_{\star} < 10.5$) and high-mass ($\log M_{\star} \geq 10.5$) samples, respectively. High-mass cluster QGs host more luminous stellar haloes than the field (mean cluster-to-field $L_{halo}$ ratio of $\sim1.2$), while low-mass cluster QGs host less luminous stellar haloes (mean ratio of $\sim0.87$). Among cluster QGs of $\log M_{\star} \geq 10$, $L_{halo}$ increases with host cluster mass, but decreases for cluster QGs of $\log M_{\star} < 10$. These results suggest higher-mass cluster QGs ($\log M_{\star} \geq 10$) experience enhanced stellar halo growth over 0.1 $\leq$ $z$ $\leq$ 1.0 fueled by increased merger-driven accretion, likely from minor mergers in cluster outskirts or in pre-infall group and filament environments. Lower-mass cluster QGs ($9.66 \leq \log M_{\star} < 10$) instead have suppressed stellar halo growth in clusters and likely lose outer stellar material to environmental stripping or accretion by high-mass galaxies during mergers.

In astronomical imaging, the low photon count of exposures necessitates extensive post-processing steps, including contamination removal and denoising. This paper evaluates deep-learning denoising methods that can be trained without clean ground-truth images and assesses their utility for detection11 oriented analysis of astronomical data. We adapt and compare Noise2Noise, Stein's Unbiased Risk Estimator, and blind-spot-based methods using synthetic data and real observations from the Hubble Space Telescope (HST) and the Canada-France-Hawaii Telescope (CFHT). Performance is evaluated using object-detection metrics, including correct detection rate and false alarm rate, together with image-based metrics and pixel-distribution diagnostics. The results show that these methods can improve faint-source detectability relative to the original noisy images, with encouraging gains on HST data after domain-consistent initialization, while transfer to CFHT data is more limited, highlighting the importance of instrument/domain similarity for unsupervised adaptation.

Star clusters, as dynamically rich environments, are thought to be important sites for the formation of contact binaries. To investigate this, we conducted a systematic search for contact binaries within two young open clusters, COIN-Gaia 25 and Mamajek 4, and their associated tidal tails. From this search, we identified and confirmed two contact binary systems: ASASSN-V J064923.44+013758.4 in the tidal tail of COIN-Gaia 25, and ASASSN-V J173229.06-613712.5 in the tidal tail of Mamajek 4. Using TESS light curve data, we performed detailed modeling with a Markov Chain Monte Carlo (MCMC) method within the 2015 version of the Wilson-Devinney (W-D) code. The resulting photometric parameters are: q_ph = 0.316 (0.013), i= 76.9 (+1.3, -0.9) degrees, f=23.1 (+1.4, -1.9)% for ASASSN-V J064923.44+013758.4, and q_ph = 0.130 (0.004), i= 68.4 (+1.4, -1.3) degrees, f=66.3 (+5.0, -5.3)% for ASASSN-V J173229.06-613712.5. A cool-spot model located on the more massive component was successfully implemented for each system. The derived parameters classify ASASSN-V J173229.06-613712.5 as a deep, low-mass-ratio contact binary. Its location in the tidal tail of Mamajek 4 constrains its age to < 371 Myr, supporting the view that the total lifetime of some contact binaries may be as short as a few thermal timescales. After evaluating standard formation mechanisms, we propose that ASASSN-V J173229.06-613712.5 likely formed via efficient orbital hardening (potentially mediated by gas dynamical friction) during the early, gas-rich phase of its host cluster's evolution. This study demonstrates the value of young clusters and their tidal tails in providing robust age constraints to explore the formation and rapid evolution of contact binaries.

We present our discovery of a complex ionized outflow in SDSS J101034.28+372514.7 (J1010+3725), a dust-obscured galaxy (DOG) at $z=0.282$. The SDSS optical spectrum of J1010+3725 shows five narrow components with one broad component in [O{\,\sc iii}]$\lambda$5007, which represents one of the most complex outflow structures observed among dusty active galactic nuclei. Spectrum fitting shows that the five narrow components have a wide range of velocity shifts (from $-1475$ to $+507$ km s$^{-1}$). The possible multiple peaks are also observed in [O{\,\sc iii}]$\lambda$4363 and [Ne{\,\sc iii}]$\lambda$3868, which allows us to investigate the physical condition of the outflowing gas by comparing the measured emission-line flux ratios with photoionization models. The comparison suggests that the five outflowing components are characterized by high hydrogen densities ($\gtrsim 10^5$ cm$^{-3}$). Our results imply that the five highly dense gas components may be outflowing with multiple bulk velocities at the innermost part of the narrow-line region in J1010+3725.

Arid terrestrial exoplanets are potentially abundant and are thus interesting targets in the search for life. In particular, M-dwarf planets such as those in the TRAPPIST-1 system may possess limited surface water, whereas early solar system terrestrials may have had small surface water inventories postmagma ocean solidification. On modern Earth, there is enough surface water for a balanced geologic carbon cycle, meaning silicate weathering balances the volcanic outgassing of CO2. However, on arid planets, there may not be enough surface water for this silicate weathering thermostat to maintain habitable conditions. Here, we show that arid planets enter a regime where weathering cannot keep up with volcanic degassing of CO2. Using a coupled model of the geologic carbon cycle, we find that terrestrial Earth-like planets require an initial surface water inventory of at least ~20-50% of Earth's ocean mass to maintain a balanced geologic carbon cycle and temperate surface temperature over 4.5 Gyr of evolution. Arid planets with less than ~20-50% of Earth's oceans cannot maintain high silicate weathering fluxes, potentially causing a runaway increase in atmospheric CO2. In addition, we explore Venus-like instellations and find that limited surface water could have destabilized Venus's carbon cycle, triggering a transition from temperate to uninhabitable. Even if a planet resides in the habitable zone of its star, if arid, it may transition to an uninhabitable state due to an unbalanced carbon cycle. More broadly, arid terrestrial exoplanets are less likely to remain habitable on long timescales, and may thus be poor candidates for biosignature searches.

We present the second paper in our program characterizing the impact of massive neutrinos on the multiscale cosmic web using global topology and persistent homology. Building on the methodology established in Paper I, based on discrete Morse theory, we analyze a subset of the Quijote simulations to compute persistent diagrams, Betti curves, and additional topological statistics for both dark matter and halo density fields, across redshifts z=0,1,2. A central result of our study is the first clear demonstration that apex points in persistent diagrams are especially sensitive to neutrino mass, with enhanced sensitivity for specific pairs of saddle points at high redshift. In addition, Betti curves from dark matter density fields broaden and flatten with increasing neutrino masses, exhibiting two characteristic density thresholds where Betti numbers remain invariant. These mass-dependent signatures are detectable at the few-percent level, even for $M_{\nu} \sim 0.1$ eV, providing a robust, physically grounded probe of massive neutrinos in the cosmic web. While traditional two-point statistics encode only pairwise correlations and cannot fully break parameter degeneracies, persistent homology captures higher-order, multiscale information that can lift these degeneracies. Moreover, its high sensitivity to the sum of neutrino masses makes it a promising complement to conventional analyses. Our results thus establish a solid foundation for forward-modeling or emulator-based approaches using persistent homology and environment-based statistics to constrain neutrino mass - potentially enabling direct detection - and additional cosmological parameters, with immediate relevance for ongoing and upcoming galaxy surveys, including DESI, Euclid, and Rubin-LSST.

In a search for low surface brightness radio nebulae using the ASKAP-EMU survey, we discovered a faint radio shell, G289.6+5.8, and its central point radio source at the position of the soft gamma-ray source IGR J11187-5438. The central radio source is spatially coincident with a previously known low-mass X-ray binary (LMXB) with an M-type donor star. However, the newly determined Gaia DR3 distance of 267 pc and correspondingly low X-ray luminosity (3 x 10e31 erg/s) cast doubt on the LMXB classification. Neither radio nor X-ray pulsations are detected. Chance-alignments between radio shell, central radio source, optical star, gamma-ray, and X-ray sources appear unlikely. By combining all currently available evidence, we conclude that G289.6+5.8 is a remnant of a low-energy core-collapse explosion of an intermediate mass star (~8Msun) in a binary system with an M-type secondary, which remained bound after the explosion. In this scenario, G289.6+5.8 is a supernova remnant, while the central gamma- and X-ray source is associated with a young neutron star driving a pulsar wind interacting with its M-type stellar companion, making IGR J11187-5438 a nascent spider-type X-ray binary.

The Cosmoglobe project is a global effort to jointly analyze complementary cosmological and astrophysical datasets, in order to better understand our Universe and its evolution. This paper describes the goals and motivations of the project, some of the main results and future prospects.

Einstein's Weak Equivalence Principle (WEP), the universality of free fall, is a fundamental component of general relativity and other metric theories of gravity. Its validity can be tested through the post-Newtonian parameter gamma, which quantifies the amount of spacetime curvature due to the presence of unit rest mass. In this paper, we use high-energy neutrino events detected by IceCube and associated with the gamma-ray blazars TXS 0506+056 and PKS 0735+178 to test the WEP via the Shapiro delay induced by the gravitational potential of Laniakea. We find that violation of the equivalence principle for neutrinos and photons is limited to an accuracy of 10^-6, 10^-7 and 10^-8, representing improvements of one, two, and three orders of magnitude, respectively, over previous constraints obtained from other high-energy neutrino-blazar associations and up to six orders of magnitude tighter compared to the constraints obtained with MeV neutrinos from SN1987A.

The characteristics of Gaia catalogues, such as trigonometric parallaxes and proper motions of stars, are discussed. Radial velocities of stars are also important for studying spatial motions. The most important results of the kinematics analysis of stellar groups from the nearest vicinity of the Sun are noted, where Gaia data allow estimating a number of parameters with unprecedentedly high accuracy. The issues related to the rotation of the Galaxy and its spiral structure are touched upon. The properties of the Radcliffe wave are discussed in the light of new data. An answer is obtained to the question of the existence of an analogue of the Radcliffe wave in other places of the Galaxy. The discovery of a phase spiral in the $z-V_z$ plane, made using Gaia data, is noted.

Long-term integrations of asteroid orbits with high-accuracy numerical integrators are essential for understanding dynamical evolution and ejection from the Solar System, but are computationally expensive. Here, we investigate the dynamical behaviour of asteroids and explore machine-learning (ML) and deep-learning (DL) approaches as efficient, scalable alternatives for classifying long-term dynamical outcomes. While the ML classifiers are trained on initial orbital elements, the convolutional neural network is trained on recurrence plots derived from short-period numerical integrations generated with the MERCURY integrator. Ensemble tree models perform strongly on the ephemeris input, and the neural network captures temporal signatures of chaotic motion with comparable or slightly improved accuracy. Backward integrations reveal partial overlap between forward- and reverse-ejected sets, illustrating time-asymmetric behaviour in chaotic regions; these backward results are interpreted only as diagnostic probes rather than reconstructions of past histories. Non-ejected asteroids largely correspond to known dynamical groups, underscoring the constraining role of initial orbital configuration. These methods provide scalable frameworks to complement numerical integrations and inform prioritisation for detailed long-term dynamical studies, with implications for planetary-defence analyses.

Red giants are tracers of stellar evolution & Galactic structure & their asteroseismic properties, particularly large frequency separation, frequency of maximum oscillation power & dipole-mode period spacing, provide direct insight into their internal structure, masses & evolutionary states. Until now, seismic inferences on large stellar samples relied primarily on high-quality light curves from missions such as Kepler & TESS, or on moderate-resolution spectroscopy (LAMOST: R ~ 1800 & APOGEE: R ~ 22500) that clearly preserve information correlated with these seismic quantities. With Gaia XP spectra (R ~ 15-85), the possibility arises to extend asteroseismic measurements to orders of magnitude more stars, despite the much lower spectral res. . Our goal is to assess whether XP spectra retain enough information to enable reliable seismic inference for RGs. We develop hybrid CNN-LSTM models trained on RGs with seismic parameters measured from Kepler photometry. The networks learn the subtle spectral signatures, imprinted through global stellar properties, that correlate with \Delta\nu, \nu_max & \Delta\Pi_1. The models recover all three global asteroseismic parameters from Gaia XP spectra with accuracies comparable to results based on moderate-res. surveys such as LAMOST, demonstrating that even low-res. spectrophotometry carries sufficient information for seismic prediction. Saliency analysis reveals wavelength regions most strongly associated with seismic sensitivity & highlights physically distinct spectral behaviour between RGB & RC stars. Applying our models to Gaia DR3 yields seismic predictions for more than 2.5 M bright RGs, enabling population-level asteroseismic studies on an unprecedented scale. We also identify a small subset of low-\Delta\nu red clump candidates showing unusual spectral-seismic correlations, offering new avenues for investigating evolved stellar populations.

We report the discovery of a radio-quiet to radio-loud transition in the narrow-line Seyfert 1 galaxy J1105+1452. The source has undergone a long-term evolution from a radio-quiet state in the 1990s to a persistently radio-bright state after 2017. Post-2017 flux densities in the $0.8$-$7$ GHz range cluster between $32$ and $43$ mJy, whereas the $144$ MHz flux density is only $1.94 \pm 0.23$ mJy. This indicates strong low-frequency suppression from a compact, absorbed component. Modeling the radio spectral energy distribution with a synchrotron self-absorption model yields a turnover frequency $\nu_{\rm p} = 0.48 \pm 0.03$ GHz and a peak flux density $S_{\rm p} = 38.9 \pm 4.7$ mJy. These parameters classify J1105+1452 as a megahertz peaked-spectrum source, consistent with the new episode of an early-stage compact jet. Under the assumption of equipartition, we derive an intrinsic physical radius $R \sim 0.68$ pc and an average apparent expansion velocity $\beta_{\rm app} \approx 0.64$. The observed brightness temperature $T_b \approx 6.0 \times 10^{11}$ K necessitates a Doppler factor $\delta \approx 12$, implying a relativistic jet viewed at $\theta \lesssim 5^\circ$. Despite the dramatic radio evolution, the X-ray spectrum remains stable and steep ($\Gamma \simeq 3.0$), suggesting that the X-ray emission remains dominated by the disk-corona, while the radio band has become jet-dominated. Our results identify J1105+1452 as a rare radio changing-state NLSy1, providing a unique laboratory for studying the birth and early evolution of relativistic jets at high Eddington ratios.

We derive a complementary cosmological upper bound on the fraction of dark matter residing inside massive compact halo objects (MACHOs) using the cosmic dawn and dark ages global 21-cm signal $(T_{21})$. MACHOs of masses $M\gtrsim 10^3~M_\odot$ moving through the post-recombination baryonic fluid transfer kinetic energy to the intergalactic medium via dynamical friction, raising the gas temperature and distorting the 21-cm signal from the $\Lambda$CDM prediction. We consider both a monochromatic and two extended MACHO mass distributions: log normal and critical collapse. Imposing the conditions that the deviation in the global 21-cm signal $\Delta T_{21}$ does not exceed $50~\rm mK$ at $z\sim 17$ or $15~\rm mK$ at $z\sim 89$, and that no emission signal appears at $z \gtrsim 300$, we derive upper bounds on the MACHO fraction $f_M$ across the mass range $10^3 \lesssim M_c/M_\odot \lesssim 10^7$. The dark ages criterion yields constraints that are both tighter and free from astrophysical uncertainties associated with star formation, providing a complementary cosmological window. Extended distributions produce bounds that are generally more stringent than their monochromatic counterpart, with the critical collapse models yielding the strongest constraints at intermediate masses.

Possibilities are considered to simplify the computation of several statistical functions used to test statistical hypotheses when processing observations: the inverse normal distribution, the Student's t-distribution, and the criterion for rejecting outliers. For these three cases, simple approximation expressions are proposed for the quantiles of these statistical distributions, which are accurate enough for most practical applications.

Magnetohydrodynamic (MHD) turbulence is a ubiquitous dynamical state of astrophysical plasmas and a primary agent in the redistribution, dissipation, and conversion of energy into particle populations. Yet turbulence is still most often described in terms of cascades, spectra, and scale-to-scale transfer, while its role in producing localized sites of intense energization remains comparatively underemphasized. In this forward-looking review, aimed at a broad astrophysical readership, I argue that any physically complete picture of turbulent plasma heating and particle acceleration must place the self-consistent emergence of coherent structures at its center. Current sheets, vortical structures, magnetic flux ropes, shocklets, and confined reconnection sites are not secondary by-products of the turbulent cascade; they are its dynamically dominant dissipative and energizing elements, where electric fields intensify, dissipation becomes highly localized, and particles undergo repeated acceleration. Viewed in this way, strong turbulence provides a unifying framework that links large-scale plasma dynamics to the generation of suprathermal particles and non-thermal energy distributions in the solar atmosphere, the solar wind, shock environments, and a wide range of other cosmic plasmas. Rather than attempting an exhaustive survey of the literature, this article offers a selective and physically organized synthesis of the field, emphasizing the mechanisms, regimes, and open problems most relevant to the development of predictive theories of particle acceleration in turbulent plasmas. It also identifies the principal conceptual and computational challenges that must be overcome if the next generation of models is to connect multiscale plasma dynamics with observable energetic-particle signatures.

Complex astrophysical processes regulate the growth of galaxies by injecting energy and momentum into their surroundings, redistributing baryons across megaparsec scales. The clustering of matter on these scales, as measured via weak lensing and galaxy surveys, encodes critical cosmological information on the dynamical dark energy, the nature of dark matter and the sum of neutrino masses. The suppression of matter clustering due to feedback processes limits the interpretation of cosmological measurements. Multiple probes of the baryon distribution have attempted to quantify the strength of feedback via measurements of suppression in the matter power spectrum. The dispersion measures (DMs) of fast radio bursts (FRBs) have emerged as a powerful new probe of baryons, with the advantage over other probes of being unbiased with respect to density and temperature. Here, we use a sample of 109 FRBs with redshifts and DMs to directly measure the spatial fluctuations in the baryon density field, quantifying the effects of feedback on the matter power spectrum at scales of $k \sim 0.1-3$ h/Mpc, and the gas fraction in galaxy groups and clusters ($10^{13}-10^{15} M_\odot$). We use a halo-model prescription to conduct inference, and find that FRB data reduces the posterior variance at k $\sim$ 1 h/Mpc by a factor of $\sim 8$ relative to the prior. The statistical precision of inferred FRB constraints is similar to other baryon tracers, while probing a complementary redshift regime ($z \lesssim 0.3$). A comparison with several hydrodynamical simulations excludes extreme large-scale feedback scenarios at $\sim 2\sigma$ confidence. This work establishes FRBs as a sensitive probe of feedback-regulated structure formation. As next-generation experiments deliver orders-of-magnitude larger samples, FRBs are poised to drive the constraints on baryonic physics in the era of precision cosmology.

Recently, a mechanism for generating astrophysically relevant magnetic fields via ultralight pseudoscalar dark matter, through the coupling term $g_{\phi \gamma} \phi F_{\mu \nu}\tilde{F}^{\mu\nu}$ in the Lagrangian density, was proposed in Brandenberger et al (2026) (see Ref. 1). In this scenario, the electromagnetic fields are amplified through the phenomena of parametric resonance due to the oscillatory behaviour of the pseudoscalar field. However, the analysis presented in that work does not account for the effects of a conducting medium. In this paper, we incorporate the finite conductivity of the plasma into the dynamics of the pseudoscalar and electromagnetic fields. We show that, due to the large conductivity relative to the Hubble parameter, the amplification of the electromagnetic fields due to parametric resonance is significantly suppressed. Consequently, we find that, for observationally viable values of the coupling between the electromagnetic field and the ultralight pseudoscalar field, it is not possible to generate magnetic fields of sufficient strength to explain their presence in cosmic voids.

Apparent slipping motions of flare ribbon kernels and the formation of hard X-ray (HXR) footpoints are important signatures of magnetic reconnection in solar flares. Ultraviolet (UV) and HXR ribbon emission can show quasi-periodic pulsations (QPPs), but the link between HXR QPP sources and slipping reconnection remains poorly understood. In this work, we analyze high-cadence IRIS and STIX observations of the 2022 March 31 M9.6 flare. STIX detected non-thermal QPPs with periods of $\approx$35 s from two relatively stationary footpoints. The majority of the HXR QPPs were correlated with UV pulsations observed by the IRIS Slit Jaw Imager in ribbon regions encompassing these footpoints. In one such region observed under the IRIS slit, the Si IV 1402.77Å line exhibited pulsations in intensity, Doppler shift, and width, some of which were coincident with HXR QPPs. Apparent slipping motions of the UV kernels were also observed, but their locations, timing, and UV intensity variability showed lower correlation with the HXR QPPs. The ribbons along which the slipping kernels were found correspond well to footprints of quasi-separatrix layers (QSLs), regions of high magnetic connectivity gradients, identified using a NLFFF extrapolation. Our multi-instrument analysis suggests that strong deposition of energy by non-thermal electrons was concentrated in a specific loop system within a large-scale 3D reconnection structure. Slipping kernels were subjected to weaker, if any, energization by non-thermal electrons, offering new constraints on 3D reconnection and flare energy release.

We perform a detailed asteroseismic analysis of four red giants observed by Kepler: KIC 9145955, KIC 9970396, KIC 9882316, and KIC 11968334. Our study is based on individual oscillation frequencies, with particular emphasis on gravity-dominated (g-dominated) mixed modes. These modes are highly sensitive to the deep stellar interior and serve as powerful diagnostics of core structure, convective overshooting, and internal rotation. Moreover, surface effects have minimal impact on g-dominated mixed modes. To ensure accurate frequency matching between observations and theoretical models, we apply a mode-identification technique that effectively distinguishes p-dominated from g-dominated modes. Although a definitive confirmation of this trend requires a substantially larger asteroseismic sample, our best-fitting models suggest that the derived convective overshooting parameter ($f_{ov}$) increases with stellar mass. In particular, within our sample the star with a mass exceeding $1.4M_{\odot}$ requires $f_{ov} > 0.01$, whereas lower-mass red giants tend to have $f_{ov}$ <0.01. In addition, the average core rotation rate of KIC 11968334 is precisely determined to be $0.7409\pm0.0113 \mu$Hz from the asteroseismic model.

Calibrating large volumes of Very Long Baseline Interferometry (VLBI) data traditionally requires significant human intervention at every stage. While the Common Astronomy Software Applications (CASA) package is the standard data reduction tool across major radio observatories, no existing CASA-based pipeline operates in a fully automated manner across the heterogeneous data formats produced by the Very Long Baseline Array (VLBA) over three decades of operations. The Search for Milli-Lenses (SMILE) project, requiring the calibration of ~5000 VLBA sources, makes such blind automation a practical necessity. We introduce the VLBI and SMILE-based CASA Optimizations (VASCO) pipeline, which automates the calibration of archival VLBA data. VASCO extends the CASA-based rPICARD framework by automating preprocessing of FITS-IDI and Measurement Set data formats, calibrator and reference antenna selection via FFT-based fringe detection, and execution of the full calibration workflow. Progress tracking is handled by ALFRD (Automated Logical Framework for executing Dynamic scripts), which orchestrates pipeline execution and records results in real time. VASCO was validated on 1000 NRAO archival sources spanning 1995-2023, covering 1372 band-separated observations across the S, C, X, U, and K bands. Calibrated output was produced for 978 sources (97.8%), with 22 failures due to corrupted or incomplete data. Mean per-source execution time was ~30 minutes using MPI parallelization with up to 20 cores. VASCO demonstrates that fully blind calibration of heterogeneous archival VLBA data is achievable with CASA. The automated calibrator and reference antenna selection will be incorporated into a future rPICARD release, extending blind calibration to any supported array. VASCO and ALFRD are available as open-source Python packages.

We test the standard Kardashev conjecture, which models the energy production of technologically advanced civilisations as growing at a fixed rate of one percent per year, against six decades of global energy production data (1965--2024) drawn from the Our World in Data energy dataset. The standard Kardashev one-percent exponential model is a poor fit to the data: the posterior growth rate obtained via Markov Chain Monte Carlo (MCMC) inference is $r = 2.01\% \pm 0.03\%\,\mathrm{yr}^{-1}$ (95\% credible interval $[1.94\%, 2.08\%]$), placing the Kardashev one-percent value well outside the credible interval. A linear Ordinary Least-Squares (OLS) model provides an excellent fit ($R^2 = 0.987$) and is preferred over the free-parameter exponential model by the Widely Applicable Information Criterion ($\Delta\mathrm{WAIC} = 5.5$). The year-over-year energy increments exhibit significant non-Gaussian structure (Shapiro--Wilk $W = 0.925$, $p = 0.0014$), with negative skewness (skewness $= -0.664$) attributable to identifiable crisis events (2008, 2020), revealing path-dependence incompatible with the memoryless multiplicative structure required by any exponential growth model. However, extrapolation of the linear model to the Kardashev Type~II threshold -- the total bolometric luminosity of the Sun, $L_\odot = 3.828 \times 10^{26}\,\mathrm{W}$ -- yields a civilisational transition timescale of $\sim 1.6 \times 10^{15}$\,yr: approximately $10^5$ times the age of the Universe and more than $10^4$ times the remaining main-sequence lifetime of the Sun. This is a physical reductio ad absurdum we term $\textit{Kardashev's Conundrum}$.

We present the discovery of `A Giant Ring on the Sky' (GR); a ring-like, ultra-large-scale structure at z~0.8, located in the same field that contains the previously-documented Giant Arc (GA) and Big Ring (BR). The GR was predicted from the presence of a Northern Arc (NA) filament (noted in previous work), which looked like it could, with more or enhanced data, connect with the GA to form a giant ring that encompasses the BR. There is now much evidence to support the reality of a GR. There appear to be two overlapping versions of the GR which differ by only the left-hand-side trajectory; this branching in the LHS of the GR was identified with the FilFinder algorithm and appears to correspond to both the GR prediction (the extended, elliptical, GR from the GA+NA ellipse), and the visually-identified ellipse (the visually-impressive, almost contiguous, roughly circular, GR which is enhanced by a tilted viewing angle). The branching in the GR seems to be hinting at multiple, overlapping ring features. The GR consists of a thin, filamentary northern region, a clustered, ambiguous southern region (including the members of the GA), and filamentary branching towards the LHS. Statistical assessment with elliptical shells, and optimum elliptical-shell-matching, identified two $> 4\sigma$ ellipse features corresponding to the GR prediction and to the visually-identified GR. Additionally, the 2D Power Spectrum Analysis identified significant ($3.5 \sigma$) clustering on scales ~320Mpc. We also applied our statistical assessments to random data and to FLAMINGO-10K simulated data. The results demonstrate that, while superficially `significant' elliptical shells can be reproduced in random data with the optimum ellipse-matching method (many trials giving the `look-elsewhere' effect), with 2D PSA all of the random fields, and FLAMINGO-10K fields, were found to be entirely consistent with random.

The recent detections of thioformyl cyanide (HCSCN) and propynethial (HCSCCH) in TMC-1 provide critical insights into the interstellar sulfur inventory, yet their sequestration and survivability on dust grain mantles remain poorly constrained. Here, we present a computational study of the site-specific adsorption of HCSCN and HCSCCH on amorphous solid water (ASW), modelled via water clusters (H2O)n, n = 6-16, at the wB97X-D/def2-TZVP level of theory, corroborated by QTAIM topological analyses and TD-DFT vertical excitations. Our results reveal a highly heterogeneous binding environment, with desorption energies spanning 1500 to 4900 K. Strongly bound cavity sites induce significant Stark shifts in the C=S stretching modes. Crucially, while the ice matrix exerts a negligible solvatochromic shift on UV transition wavelengths, deeply bound CN-cavity configurations exhibit a pronounced hyperchromic enhancement of the oscillator strength. Implementing these site-specific parameters into the UCLCHEM gas-grain code demonstrates that these species undergo a gradual thermal desorption profile rather than a singular sublimation event. Furthermore, the hyperchromic effect establishes a Survival Paradox: while deeply trapped populations are thermodynamically shielded against thermal desorption, they simultaneously possess enhanced UV absorption cross-sections, rendering them vulnerable to photodissociation by the interstellar radiation field prior to sublimation.

A primary goal of the Habitable Worlds Observatory (HWO) is to detect and measure the abundance of biosignature molecules, such as water (H2O) and oxygen (O2), in the atmosphere of Earth analogs. This is expected to require deep spectroscopic observations lasting hundreds of hours per planet. In this context, it is essential to optimize the spectral resolution of the spectrograph to both maximize the number of planets that can be studied over the lifetime of the mission, and also to reduce the risks of false detections. The purpose of this work is to provide a framework to explore the spectral resolution design trade-space for HWO. This framework must be valid and comparable across all spectral resolutions from low (R<100) to high resolutions (R>10,000), and account for the spectral correlation of the residual starlight (i.e., speckle noise chromaticity). Leveraging the concept of "template matching", we develop a simulation toolkit based on the Python package EXOSIMS to compute the detection significance of planets and molecules. We then simulate observations of Earth analogs around 164 stars using representative mission parameters to explore the effects of the detector noise and the correlated speckle noise floor. Our findings suggest that a moderate or high resolution spectrograph (R>1,000) will provide higher sensitivity to critical molecules compared to a low resolution spectroscopy mode (e.g., R~140). The correlated speckle noise may also entirely suppress our ability to detect bio-signatures at low spectral resolutions. We conclude that a more comprehensive study combined with detailed models of its stability, and other sources of correlated noise, is necessary to fully explore the trade space of spectral resolution and detectability of key species.

The acceleration of cosmic rays up to PeV energies at supernova remnant shocks requires an amplification of the ambient magnetic field. The amplification mechanism must operate upstream of the shock, to prevent the escape of particles from the system. Observational evidence of field amplification has been indeed obtained by means of X-ray observations. However, such observations constrain the magnetic field strength downstream of the shock only. Here we describe a mechanism for magnetic field amplification that operates downstream of the shock. It is based on a plasma instability triggered by the drift of charged interstellar dust grains overtaken by the shock. We compute the growth rate of the instability, we estimate the level of magnetic field amplification expected downstream of supernova remnant shocks, and we compare our results with observations. In some cases (most notably Cas~A) this mechanism might explain the presence of the X-ray filaments observed at supernova remnant shocks, without requiring any amplification of the magnetic field upstream of the shock and therefore no acceleration of CRs to ultra-high energies.

We present a method for transforming galaxy rotation curves into radially resolved dynamical chronometers, enabling reconstruction of galaxy assembly histories directly from kinematic data. Within the Nexus Paradigm, the baryonic Tully-Fisher relation provides an estimate of the dynamical mass profile $ M_{dyn}(r)=v^4/Ga_0$, where $a_0=H_0/2\pi $.By Comparing this with independently derived intrinsic baryonic mass profiles, $M_{int}(r)$, obtained from stellar Sérsic fits and gas surface density measurements, we construct the ratio $ M_{dyn}(r)/M_{int}(r)$, which maps directly to a formation redshift via $ 1+z_{form}(r)=(M_{dyn}/M_{int})^{1/4}$. Inverting this relation with$\Lambda CDM$ cosmology yields a radial lookback-time profile, $t_{lb}(r)$, representing the time since the last dynamical reconfiguration at each radius. Applying this framework to a pilot sample of SPARC galaxies spanning high-and low -surface-brightness systems, together with the Milky Way, we recover diverse radial age structures, including flat profiles consistent with coherent disk assembly and stratified profiles indicative of inside-out growth. The method operates without dark-matter halo fitting and provides a kinematic chronometer complementary to stellar-population and chemical-evolution approaches. While the inferred ages depend on the accuracy of baryonic mass reconstruction and local applicability of the evolving baryonic Tully-Fisher relation, the results demonstrate that galaxy rotation curves encode time-resolved dynamical information. This establishes the radial dynamical chronometer as a new observable for probing galaxy evolution and testing gravitational frameworks.

The positions of more than 1300 nova eruptions in M31 catalogued through the end of calendar year 2025 have been compared in order to identify recurrent nova candidates. The work extends the study of Shafter et al. (2015) who identified a total of 12 recurrent novae with high confidence (plus four possible recurrent novae) from an analysis of 964 M31 novae observed prior to 2014. During the past 12 years an additional seven recurrent novae have been discovered in M31. In addition, we have confirmed that one of the possible recurrent novae is in fact recurrent (M31N 1990-10a), while another was shown to be a foreground dwarf nova (M31N 1966-08a). At present, there are a total of 79 nova eruptions associated with 20 known recurrent novae in M31, with four additional eruptions from two candidates remaining unconfirmed. A comparison of the spatial distribution of the recurrent novae with that for all novae shows no significant difference between the two. In addition, we find no significant difference between the light curve properties (peak luminosities and rates of decline) between the M31 and Galactic recurrent nova populations. However, the recurrence time distributions appear different, with half of the M31 recurrent novae having recurrence times shorter than U Sco, the Galactic recurrent nova with the shortest known recurrence time, $T_\mathrm{rec}=10.3$ yr. As expected, recurrent novae are found to be both fainter and faster than novae generally, being mostly found in the lower left quadrant of the MMRD plane.

Identifying new observational probes to constrain cosmological parameters has become an important goal in modern cosmology. In this work, we explore the potential of the cosmic star formation rate density (SFRD), compiled over the redshift range $z \in [0, 15]$, as a complementary probe of fundamental parameters, including $\Omega_{\rm m}$, $H_0$, and the dark energy equation-of-state parameter, $w$. Within the $\Lambda$CDM framework, SFRD combined with BBN data alone yields $H_0 = 65\pm11$ km\,s$^{-1}$\,Mpc$^{-1}$, reflecting significant degeneracies with astrophysical parameters. By jointly analyzing SFRD with recent BAO and Type Ia supernova (SNIa) data, these degeneracies are effectively broken, resulting in much tighter constraints, e.g., \texttt{SFRD + BBN} + \texttt{DESI-DR2} gives $H_0 = 68.28 \pm 0.18$ km\,s$^{-1}$\,Mpc$^{-1}$. We perform a statistical reconstruction of the SFRD as a function of redshift, finding a peak at $z_{\rm peak} = 2.600^{+0.114}_{-0.087}$ within $\Lambda$CDM. Our results demonstrate that combining SFRD with established cosmological probes not only improves constraints on cosmological parameters but also reduces uncertainties in astrophysical parameters governing star formation. We further extend the analysis to the $w$CDM model, highlighting the promise of SFRD as a robust complementary cosmological probe across different dark energy scenarios.

The cosmological principle asserts that the Universe is homogeneous and isotropic on large enough scales. However, alternative cosmological models can bring about anisotropies through local inhomogeneities, anisotropic evolution, or exotic physics. In addition, select studies have also hinted at mild evidence of anisotropies in SNe Ia, CMB, and GRB data, though these remain unconfirmed. In this work, we test for cosmological anisotropies using gravitational waves and gamma-ray bursts, adopting the latest O4a release from the LIGO-Virgo-KAGRA collaboration and GRBWeb (including all known GRBs since 1991). If the cosmological principle holds, the sky localisation and the characteristics of the GRBs and GWs (masses, luminosities, redshifts) should be statistically isotropic when corrected for selection biases. We employ a couple statistical methods, including angular power spectra and two-point correlation functions, and compare the results against synthetic data. The work extends previous analyses by including the most recent datasets, and the use of multiple complementary statistical tests. We find no significant evidence for anisotropy in the current GW and GRB datasets, consistent with the cosmological principle.

Isolated dwarf galaxies are intrinsically faint and difficult to detect. The limited sample size makes it challenging to observationally constrain the physical mechanisms that quench their star formation. To disentangle the quenching mechanisms of isolated dwarfs, we identify a non-negligible population of such galaxies in the TNG50 simulation. In addition to the previously discovered ``backsplash" galaxies that were quenched by environmental effects when they were once satellites in more massive halos, we find another primary quenching channel in a population of galaxies whose star formation is suppressed by excessively strong gas outflows that prevent the gas from cooling and collapsing to form stars. We further demonstrate that these outflows are highly likely driven by stellar feedback and predominantly occur in high-gas-fraction dwarfs, which within our studied stellar mass range ($10^7$--$10^{9.5},M_\odot$) are always located toward the low-mass end.

Space-borne gravitational-wave telescopes are key to extend the observation band below $10\,\mathrm{Hz}$. The use of inter-satellite optical cavities linked by heterodyne interferometry is a promising approach to reach the sensitivity level of $10^{-22}/\sqrt{\mathrm{Hz}}$ in the decihertz band. While heterodyne interferometry is advantageous for relaxing arm-length control requirements, it introduces susceptibility to clock jitter, which can be a significant noise source. In the back-linked Fabry--Perot (BLFP) interferometer aiming at the decihertz band, the required clock stability exceeds that of current space-qualified oscillators by more than an order of magnitude. We propose a clock noise cancellation scheme that uses two heterodyne signals with positive and negative beat-note frequencies, naturally obtained using both incoming and outgoing laser beams of arm cavities without additional clock modulation schemes. By forming a weighted combination of these signals with time-dependent coefficients, clock jitter contributions are eliminated while preserving gravitational-wave information. We present the theoretical framework, analyze performance under realistic arm-length drifts, and validate the approach through time-domain simulations using parameters from the B-DECIGO concept. Results show that the synthesized signal recovers the original sensitivity and even improves the signal-to-noise ratio by a factor of $\sqrt{2}$ for shot noise.

Polarization at millimeter wavelengths provides a powerful diagnostic of dust grain properties in protoplanetary disks. Standard models based on solid spherical grains often struggle to reproduce the observed polarization fractions and morphologies in systems where self-scattering is expected to dominate. We investigate the impact of grain morphology on polarized millimeter emission by comparing models that adopt solid spherical grains with models that employ solid irregular hexahedral particles drawn from the TAMUdust2020 database. Both grain populations share identical size distributions, enabling us to isolate the effects of geometry while preserving the same internal structure and material density. We explore three optical-depth regimes-optically thick, optically thin, and an intermediate hybrid case-to assess how grain morphology modifies the polarization structure under different conditions. For size distributions with $a_{\mathrm{max}} \sim \lambda / 2\pi$, where scattering-induced polarization is expected to peak, we find that the polarization morphology and fraction are nearly indistinguishable between spherical and irregular grains. The primary quantitative difference is an enhancement of the scattering opacity by up to a factor of $\sim 2.5$ for irregular particles, implying that disk dust masses inferred under the assumption of spherical grains may be systematically overestimated. Irregular grains also suppress the polarization reversal predicted by Mie theory at large size parameters ($x>1$). Nevertheless, modifying grain geometry alone is insufficient to reproduce the observed polarization fractions within a pure self-scattering framework. These results suggest that additional physical effects, such as dust porosity, warrant dedicated investigation.

Accretional heating of Earth's interior during formation is pivotal to its subsequent thermal and chemical evolution. In particular, impact heating of Earth's core is expected, but its amplitude and radial distribution within the core is unknown and could influence the onset of the geodynamo. The uncertainty is due, in part, to the lack of constraints on the temperature of the interior following formation due to the difficulty of preserving a record of such a high energy environment, and the assertion that super-heating during formation would be rapidly lost through magma ocean cooling. Here we systematically investigate core heating due to giant impacts using a Smoothed Particle Hydrodynamics (SPH) code with simulations spanning a range of impact angles, velocities, and masses. From these simulations we derive a scaling relation for core heating that depends on the impact parameters and predicts the radial core temperature profile following the impact. Our findings show that a significant amount of heat is deposited into the core, with a canonical impact scenario resulting in an average core temperature increase of about 3000 K, approximately 500 K higher than that of the overlying mantle. In this case the heat distribution within the the core produces a strong thermal stratification. We use a parameterized cooling model to estimate that the core could have cooled to an adiabatic state 290 Myr after a canonical impact, which is consistent with the observed time span between the age of the Moon and evidence for an active geodynamo.

A subset of magnetic stars exhibit periodic radio pulses produced by the coherent electron cyclotron maser mechanism. These pulses are known to exhibit both temporal and spectral variations, which have been attributed to phenomena intrinsic to the stellar magnetosphere. However, in order to fully characterise the radio pulses and use them as magnetospheric probes (as suggested by past studies), it is also important to consider the effects of phenomena extrinsic to the magnetosphere. In this paper, we investigate whether interstellar scintillation could be a relevant mechanism for explaining spectral and temporal variations observed for coherent stellar radio emission. For that, we consider the case of the well-characterised magnetic hot star CU Vir. At 400 MHz, coherent radio emission from the star was reported to exhibit a peculiar spectral evolution that remains unexplained. We show that a plausible level of turbulence along the line of sight can produce the observed phenomenon of spectral features. Our analysis shows that diffractive interstellar scintillation can have a strong effect on the observed dynamic spectrum of radio emission from stars, for an assumed size of the emitting region of $0.01r_\odot$, and that caution should therefore be taken in separating intrinsic and extrinsic features, particularly at low frequencies. These results are preliminary and further work is required to fully model the scintillation of ECME from stars (in particular the change in source location with frequency), and to explore the full range of plausible scintillation parameters. We suggest how further observations may be used to test the interstellar scintillation hypothesis.

The properties of the spectral evolution during the prompt emission phase of gamma-ray bursts (GRBs), which are closely related to the radiation mechanism (synchrotron or photosphere), are still a subject of debate. Two spectral evolution patterns (``hard-to-soft'' and ``intensity-tracking'') have been commonly observed in GRB prompt emission spectra. Here we present a well-defined sample of 20 single-pulse GRBs detected by \emph{Fermi} whose prompt emission spectra exhibit the intensity-tracking pattern. By performing a time-resolved spectral analysis, we derive $E_{\rm p}$ and the energy flux $F$ from the same time bins and introduce a matched-bin lag, $t_{\rm lag}^{\rm F} \equiv t_{\rm p}(E_{\rm p})-t_{\rm p}(F)$, where $t_{\rm p}$ denotes the time at which each quantity reaches its maximum. We find that the intensity-tracking pattern subdivides into three distinct subclasses: Type I (5/20), with aligned $E_{\rm p}$ and flux peaks; Type II (13/20), with $E_{\rm p}$ peaking before the flux; and Type III (2/20), with $E_{\rm p}$ peaking after the flux. The early-peaking Type~II subclass dominates the sample. The subclasses also exhibit systematic differences in their spectral and temporal properties. Type II bursts are systematically harder than Type I, show broader flux pulses, and more often display asymmetric rising and decaying $E_{\rm p}$-$F$ branches. Type I is consistent with tightly coupled spectral and power evolution, whereas Type II is more naturally explained by nonthermal or hybrid prompt-emission scenarios in which spectral hardening precedes the peak radiative output. Type III appears to form a rare positive-lag tail whose physical origin remains uncertain.

We study how rotation modifies the constraints on MeV-scale axion-like particles (ALPs) coupled to photons derived from SN 1987A. We constrain the ALP parameter space based on both the energy-loss argument and the gamma-ray limits, and examine how these constraints are affected by stellar rotation. Adopting initial angular velocities of ${\Omega}_{0} = 0.0 and 1.0 rad s^{-1}$ in the iron core, we carry out two-dimensional core-collapse supernova simulations for three progenitor models - a $14 + 9M_{\odot}$ binary and $13M_{\odot}$ and $18M_{\odot}$ single stars with solar metallicity - and estimate ALP emission rates through post-processing. We find that rotation suppresses ALP emission by reducing the core temperature via centrifugal support. Rotation also reduces the neutrino luminosity, but the suppression of ALP emission is more effective, leading to relaxed constraints within a simplified criterion based on the energy-loss argument. This relaxation is particularly pronounced in the rotating $18M_{\odot}$ model, where a substantial decrease in the central temperature occurs at $t_{pb} = 0.8 - 1 s$. In this simplified criterion, such rapid temporal variations in temperature indicate that the resulting constraints depend sensitively on both the evaluation time and the underlying supernova model. For a gamma-ray limit from the SN 1987A observation, rotation has a negligible impact on the constraint. This is because the ALP-induced gamma-ray fluence observed at Earth is proportional to the fourth power of the ALP-photon coupling constant, making the constraint relatively insensitive to the rotational suppression of ALP emission.

Thermal infrared data (TIR; 8 - 15 $\mu m$) has a wide range of applications in Earth and planetary remote sensing. On Mars, this includes deriving thermal inertia (TI), which describes surface physical characteristics (e.g. particle size, degree of cementation) and is key for understanding geologic processes, assessing in-situ resource utilisation (ISRU) environments, and assisting mission planning. However, TI data from the THEMIS instrument is limited to 100 m/pixel resolution. Hyperspectral visible and near-infrared data (VIR; 0.5 - 5 $\mu m$) compliments TIR data by providing information on surface composition and is provided by the CRISM instrument at 12 m/pixel. In this work, we generate a machine learning regressor-based model to constrain relationships between THEMIS TI and CRISM VIR images at THEMIS resolution, and predict TI values from CRISM spectra with high accuracy (R2 $\sim$ 0.90, RMSE $\sim$ 23.6 TIU). We use the model to produce a downscaled TI map at a spatial resolution of 12 m/pixel, an order of magnitude finer than currently available, revealing decametre-scale features previously unresolved in THEMIS data.

Gas delivery to galactic centers powers nuclear starbursts and active galactic nuclei (AGNs), yet bar-driven inflow is generally expected to stall in a nuclear ring a few hundred parsecs across. Using three-dimensional Lagrangian hydrodynamic simulations in a fixed barred potential, we identify a bypass channel in which a fraction of the inflowing gas acquires vertical momentum, vaults across the ring, and reaches the inner few tens of parsecs. This pathway is absent in two-dimensional calculations, which instead predict long-lived stagnation at the ring. We find that the circumnuclear material within $\sim 50$ pc originates from gas initially located outside the ring ($\gtrsim 300$ pc), rather than from secondary inflow out of the ring itself. Successful delivery requires both a sufficiently large vertical excursion, $|z| \sim 100$ pc before encountering the ring, and substantial loss of azimuthal angular momentum $L_z$. The resulting inflow is organized rather than chaotic: center-reaching trajectories are confined to a limited spatial region set by the scale height of the ring gas. Most bar-driven gas still accumulates near the resonance and fuels star formation in the nuclear ring, but the vaulting stream selects a modest yet sufficient fraction that penetrates to the circumnuclear disk. These results suggest that intrinsically three-dimensional gas motions help link nuclear starbursts, AGN fueling, and the frequent misalignment of nuclear disks with respect to their host galaxies.

The James Webb Space Telescope (JWST) has extended the frontier of galaxy detection to redshifts z>11, finding a high abundance of UV-bright sources that challenge theoretical models. However, most current results come from just a few fields, introducing uncertainties due to cosmic variance. Here, we constrain z~7-14 UV luminosity functions (LFs) over ~400 arcmin^2 across 36 independent sightlines from DR2 of BEACON, a JWST pure-parallel NIRCam multi-band imaging survey. We identify 164 7<z<12 galaxy candidates: 150 F090W-, 14 F115W-, and no robust F150W-dropouts. Based on 11 pointings overlapping with public JWST spectroscopy, we observe 100% purity. Our z~7.5 UV LF agrees with previous bright-end measurements but yields lower number densities at $-21\leq M_\mathrm{UV}\leq-19$. At z~10, our measurements are lower than most photometric JWST results but match spectroscopic constraints, consistent with the high purity of our selection. The LFs at z~7.5 and z~10 are consistent with pre-JWST models, while our limits at z>13 do not rule out a possible excess. We measure significant clustering of bright ($M_\mathrm{UV}<-20.5$) galaxies at 7<z<10. Fields hosting such sources are approximately three times more likely to be overdense relative to the full survey, implying that UV-bright galaxies preferentially reside in the most massive halos at these redshifts. Comparing with semi-numerical simulations, we estimate that $M_{\mathrm{UV}} < -20.5$ galaxies inhabit halos ~0.9 dex less massive at z~11 than at z~7, consistent with a shift to higher star formation rates. However, their observed clustering exceeds predictions from pre-JWST luminosity-halo mass relations, suggesting these sources reside in more massive halos than previously modelled and/or multiple halo occupation.

QUBIC, the Q & U Bolometric Interferometer for Cosmology, is a telescope that observes the polarisation of the sky in the millimetre-wavelength range. Its goal is to detect the primordial B-modes of polarisation in the cosmic microwave background by combining the sensitivity of bolometers with the good understanding of interferometry systematics. This dual aspect of QUBIC allows it to perform spectral imaging, that is, obtaining spatial and spectral information of the sky simultaneously. This makes the separation of components with complex spectral energy distributions easier, hence improving the performance of foregrounds removal. We developed three different map making methods (frequency, component and neural network map making) that take advantage of these characteristics. Moreover, QUBIC resumed observing the sky early March and is continuing its commisioning phase with, namely, observations of the Moon.

In a mixed dark matter scenario in which primordial black holes (PBHs) would co-exist with thermally produced self-annihilating particles, one expects the former to be surrounded by extremely dense halos made of the latter, built up during radiation domination. Here, as a continuation of previous work, we derive observational limits on such a scenario from a full statistical analysis of cosmic microwave background (CMB) data. We quantify how a tiny fraction $\fbh$ of PBHs could restrict the parameter space available to thermal particle dark matter, limiting the $s$-wave annihilation cross section to values $\lesssim 10^{-30}\,{\rm cm^3/s}\,(\mchi/100\,{\rm GeV})\,(\fbh/10^{-6})^{-3}$ if PBHs are typically heavier than $\sim 10^{-10}\,\Msun$, which can also be turned into constraints on PBHs in this mass range. In contrast, asteroid mass or lighter PBHs could live in perfect peace with these particles. Finally, we shortly discuss the implications of the recent tentative interpretation of Subaru-HSC microlensing events as PBHs.

Neutron stars make a unique astrophysical test bench for our understanding of quantum physics at kilometre scales. The rotation of a neutron star features glitches, sudden spin-ups that interrupt the otherwise regular stellar spin-down, which are often attributed to the dynamics of pinned quantised vortices in one or several of the superfluid phases inside the star. Laboratory experiments probing superfluid vortices have inspired neutron star theory and simulations from the beginning. Here we argue that vortex experiments in superfluids contained in aerogels show phenomenology that offers a highly appealing but vastly unexplored analogue for neutron star physics. We build a point-vortex simulation that allows analysing experiments in a crust-like and a core-like aerogel, extracting two different regimes of pinned vortex (non-)dynamics and validating a microscopic picture of very strong vortex pinning. In the crust-like aerogel, vortices get depinned once the ambient superflow is fast enough, while in the core-like aerogel pinned vortices are never released and rotational velocity changes are accommodated by the avalanche-like production of new vortices instead. Finally, we show that these concepts should apply also in neutron stars and may thus revolutionise the analysis of neutron star observations.

X-ray polarimetry is a new tool capable of probing the geometry of accretion onto weakly magnetized neutron stars. Here we present the first X-ray spectropolarimetric results from coordinated observations of the atoll source 4U 1735-44, conducted with the Imaging X-ray Polarimetry Explorer (IXPE), NICER, and NuSTAR. Over the 2-8 keV energy range, we obtained a marginal detection of polarization with the polarization degree of $1.4\%\pm0.7\%$ and polarization angle of $-29^\circ\pm14^\circ$, corresponding to a $3\sigma$ upper limit on the polarization degree of 3.5\%. The best-fit model to describe the spectrum comprises a thermal component associated with the accretion disk, a Comptonized blackbody component, and a relativistic reflection component. From the reflection model, we infer a disk inclination of $\sim 40^\circ$. The spectroscopic and polarimetric properties of 4U 1735-44 are consistent with those observed in other atoll sources studied by IXPE, with its low polarization likely due to its low inclination.

We propose a cosmological scenario in which, beyond matter and radiation, an additional barotropic fluid with positive equation of state $\omega_s$ contributes to the cosmic energy budget, in contrast to Early Dark Energy (EDE). We investigate the theoretical implications of this framework, here dubbed the $\Lambda_{\omega_s}$CDM model, at both the background and perturbative levels, exploring its impact on the expansion history and structure formation. We show that, while remaining subdominant at late times and therefore consistent with current observational bounds, the additional fluid modifies the early-time expansion rate, leading to a higher inferred value of the Hubble constant. Thus, we perform a full Bayesian analysis using a modified version of the \texttt{CLASS} Boltzmann code interfaced with \texttt{MontePython}, considering combinations of \textit{Planck} 2018 Cosmic Microwave Background (CMB) data, DESI DR2 Baryon Acoustic Oscillations (BAO) measurements, Pantheon Type Ia supernovae (SNe Ia), and SH0ES determinations of $H_0$. We find that the inclusion of the SH0ES prior, $H_0 = 73.04 \pm 1.04\,\mathrm{km/s/Mpc}$, leads to a preference for a nonvanishing barotropic fluid. In particular, we obtain $\omega_s = 0.290^{+0.017(0.021)}_{-0.007(0.028)}$ and density $10^5\Omega_s = 1.47^{+0.35(1.14)}_{-0.62(0.94)}$ for the dataset combination CMB + BAO + Pantheon + SH0ES, and $\omega_s = 0.302^{+0.024(0.034)}_{-0.013(0.038)}$ and $10^5\Omega_s = 1.21^{+0.31(1.10)}_{-0.65(0.86)}$ when BAO data are excluded. We further compare our scenario with the EDE framework and show that, statistically, no strong evidence is found against the $\Lambda_{\omega_s}$CDM model. Finally, we provide a physical interpretation of our fluid in terms of matter with pressure, indicating that the standard cosmological model may be incomplete in its current minimal formulation.

Smokescreen is an open-source Python library for data-vector concealment (blinding) in cosmological analyses. Data-vector blinding works by applying cosmology-dependent shifts to the observed data vector, moving it away from the true cosmological signal without affecting its statistical properties, so that analysts cannot infer the true result until the analysis is frozen and the blinding is lifted. The package computes these shifts using Firecrown likelihoods applied to data vectors stored in the SACC format, ensuring that the theoretical model used for blinding is identical to that used for inference whilst remaining agnostic to the specific observable being blinded. To prevent accidental unblinding, the original SACC file, containing the true cosmology, is encrypted. Although developed for the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST), Smokescreen is applicable to any experiment using Firecrown likelihoods and the SACC data format.

We present high-precision chemical abundances for 25 FGK-type stars hosting exoplanets observed in JWST Cycle 3 programs and all GTO and DDT programs from Cycles 1-3, based on high-resolution, high signal-to-noise ratio optical spectra from ground-based telescopes. Using a strictly differential, line-by-line analysis relative to the Sun, we derive homogeneous stellar parameters and abundances for 19 elements with atomic number Z <= 30. The sample spans a wide range of stellar properties, with [Fe/H] = -0.6 to +0.4 dex and effective temperatures between 4700 and 6600 K, and includes hosts of terrestrial and giant planets as well as multi-planet systems. We refine carbon and sulfur abundances in cool dwarfs using spectral synthesis, mitigating systematics from line blending. Several chemically interesting systems are identified, including mildly $\alpha$-enhanced metal-poor stars and multi-planet hosts with elevated [C/O]. Using isochrone ages, we derive empirical Galactic chemical evolution (GCE) relations and examine condensation temperature (Tcond) trends before and after GCE correction. The $T_{cond}$ slopes show no dependence on stellar or planetary properties, indicating that they reflect a mixture of multiple mechanisms, with planet-related signatures entangled in GCE and stellar evolution effects. Thus, Tcond trends require careful interpretation. Several systems with significantly positive or negative Tcond slopes are identified. Together with forthcoming JWST atmospheric measurements, this homogeneous stellar abundance catalog provides a basis for probing star-planet chemical connections and planet formation pathways.

Using the gravitoelectromagnetic analogy for weak gravitational fields, we critique explanations of galactic velocity profiles that invoke time delay effects (i.e. "retarded gravity"). For isotropic, time-dependent matter currents, we show within this framework that the force exerted on an orbiting body is Newtonian and due only to the instantaneous ambient matter configuration -- there are no time delay effects in such situations.

We describe the equation of state (EoS) of a warm ion plasma as obtained by performing microscopic many-body simulations using Molecular Dynamics computational techniques. Using the cold one-component plasma (OCP) composition in the Neutron Star (NS) outer crust assumed in Murarka et al. (2022) with a representative heavy nucleus for each density, we refine previous calculations. We include electron screening and modeling of ions as finite-size Gaussian distributions in the interaction potential, together with an efficient Ewald energy summation procedure. From this, the EoS relation $P(n_B,T)$ is obtained as a function of baryonic density and temperature in the NS outer crust under conditions $n_B\in[7.48\times 10^{-10},2.09\times10^{-4}]$ $ \rm fm^{-3}$ , $k_{B}T\in[1,5]$ MeV. In order to improve the usability of our results we provide tabulated data values along with a neural network parametrization available in the Zenodo repository, see this https URL. We find that even at moderate temperatures, thermal effects of ions are key in the higher density region closer to the inner crust, when described using a thermal effective parametrization based on the thermal adiabatic index $\Gamma_{th}$. We compare our results with other EoS in the literature performing a critical discussion.

This article uses an adapted version of the semi-analytical model of cosmic chemical enrichment developed by \citet{Corazza_2022} to reproduce the observed abundances of C, N, and O in absorption systems of quasar spectra (ASQS) at $z \gtrsim 3-6$, addressing an overproduction issue of the abovementioned elements. We address this discrepancy by updating the cosmic star formation rate (CSFR) and introducing intermediate-mass black holes (IMBHs) as permanent matter sinks without accounting for a dynamic cosmic mass accretion rate. Our results indicate that IMBHs act as essential metallicity attenuators through mass sequestration, providing the physical regulation necessary to reconcile theoretical yields with observed data. We show that the interplay between Pop III yields, the cosmic baryon accretion rate (CBAR) from primordial nucleosynthesis, and mass sequestration by IMBHs mitigates the CNO excess. This work reinforces the role of black hole-driven processes in the chemical evolution of the Universe and identifies IMBH accretion rates as a primary area for future refinement.

Next generation detectors, such as LISA, LGWA, and ET will, for the first time, probe the high redshift Universe, offering unique insight into the birth, growth, and dynamics of the first black holes (BHs) during their earliest stages formation. We aim to predict merger rates and gravitational wave (GW) signatures of "cosmic" binary BHs, forming as a result of galaxy mergers, at z>=4. We investigate how BH seeding, accretion physics and dynamical delays affect their properties and detectability across cosmic epochs. We use the semi-analytic model Cosmic Archaeology Tool (CAT) to trace the evolution and delayed-mergers, driven by dynamical friction, of BH binaries formed from light, medium-weight and heavy seeds, under Eddington-limited (EL) and super-Eddington (SE) accretion prescriptions. We employ the GWFish package to evaluate their GW signals and detectability by LISA, LGWA and ET. Our results show the impact of BH accretion and seeding prescriptions on the properties and distribution of detectable sources. In the EL model, the detected populations are dominated by nearly equal-mass binaries. In contrast, SE growth leads to lower mass ratios for LISA detections and medium ratios for ET and LGWA. We present the total detection rates predicted under the two accretion scenarios. The SE model allows BHs to grow faster, transferring a significant fraction of detectable systems from the ET band to the LISA band, compared to the EL model. As a result, the predicted LISA detection rate increases from ~32 yr^-1 in the EL case to ~64 yr^-1 in the SE scenario, and the ET detection rate reduces from ~64 yr^-1 in the EL model to only ~4 yr^-1 in the SE scenario. LGWA yields comparable detection rates in both scenarios (~21 yr^-1 in EL and ~12 yr^-1 in SE). The combined information encoded in mass ratios, redshift evolution and merger rates emerge as a promising diagnostic of early BH growth.

The IceCube Neutrino Observatory has opened a new window into the high-energy Universe, providing measurements of neutrinos over a broad energy range. This contribution presents recent results, including a follow-up on the first identification of a steady neutrino source NGC 1068, measurements of the flavor composition of the diffuse astrophysical flux, limits on prompt atmospheric neutrinos, and searches for neutrinos from dark matter annihilation in the Sun. These measurements probe neutrino production mechanisms, fundamental particle interactions, and physics beyond the Standard Model. Looking forward, the recently deployed IceCube Upgrade will enhance sensitivity to lower-energy neutrinos and reduce systematic uncertainties, while the planned IceCube-Gen2 will expand the detector volume, increase the neutrino detection rate, and extend energy reach, enabling more detailed studies of cosmic sources and high-energy particle physics.

We present a homogeneous metallicity analysis of old stellar populations in Local Volume (LV) galaxies using data from the CMDs/TRGB catalog of the Extragalactic Distance Database (EDD; this http URL), which provides uniformly measured TRGB distances and PSF photometry for resolved stars in over 500 nearby galaxies observed with the Hubble Space Telescope. We apply the calibration of Lee et al.(1993) to estimate the mean metallicity [Fe/H] from the (V-I) color of the red giant branch (RGB) at M_I = -3.5 mag obtaining reliable measurements for 334 galaxies out of an initial set of 558. The RGB colors were derived by locating the maximum stellar density in the (M_I, (V-I)) diagram, smoothed with a Gaussian kernel and refined via Monte Carlo simulations (500-1000 realizations), yielding typical uncertainties of about 0.03 mag. Our results show that most galaxies lie within the color range (V-I) = 1.22-1.74 of the original calibration, corresponding to metal-poor systems typical of dwarfs, with the overall metallicity distribution peaking at [Fe/H] = -1.89+-0.03 dex. We find a pronounced luminosity-metallicity relation across a wide magnitude range, from faint dwarfs (M_B > -7) mag to giant galaxies (M_B < -18), described by the regression [Fe/H] = -2.6- 0.075M_B. Both dwarf and giant galaxies follow the same relation, though ACS fields for giants often sample outer, more metal-poor regions. Morphologically, early-type dwarf spheroidals exhibit systematically higher mean metallicities than late-type dwarf irregulars.

The morphology and heliospheric impact of coronal mass ejections (CMEs) are strongly shaped by their preeruptive magnetic configuration and surrounding coronal environment, yet these influences remain difficult to constrain observationally. We analyze a complex CME that erupted on 2024 October 26 using multiviewpoint remote sensing observations and in situ measurements. Using the physics based CORHELCME magnetohydrodynamic model, we test multiple physically plausible realizations of the preeruptive magnetic flux rope (MFR) and background magnetic field, using agreement with the observed evolution as a constraint on the CMEs initial state. We find that modest changes in MFR footpoint location and force balance lead to substantially different coronal trajectories, enabling rapid discrimination among candidate initial states. While several configurations reproduce the CMEs large scale propagation, realistic small scale morphology is achieved only when a near dated background magnetic field is employed. The resulting simulation reproduces key morphologies observed from three viewpoints without fine tuning, indicating that the inferred preeruptive configuration represents a robust, global solution and provides a physically consistent interpretation of their magnetic origin. Comparison with in situ shock detections highlights the role of CME solar wind interactions in shaping heliospheric signatures, though shock arrival times remain uncertain at the 11 hr level. These results demonstrate that data informed, physics based modeling can meaningfully constrain CME preeruptive conditions and bridge remote and in situ observations, while emphasizing the need for timely magnetic field measurements to improve predictive capability.

The caustic skeleton is a parameter-free and mathematically rigorous formalism for tracing the hierarchical formation history of the multiscale cosmic web from the singularities in the underlying dark matter flow. In the present study, we explicitly use the multistreaming nature of the cosmic mass distribution to address the influence of the weblike embedding on the galaxy populations and discern their properties in different web environments. To this end, we construct the multiscale caustic skeleton of the dark mass distribution in the state-of-the-art suite of the large-scale IllustrisTNG simulations. In addition to the multistreaming dark matter density field, we assess the characteristic properties of the intergalactic baryonic gas in the vicinity of the caustics. Next, we associate the galaxies with the voids, walls, filaments and cluster nodes, and investigate their colours and star formation activities. A unique feature of the analysis is that it explicitly addresses the multiscale aspects with respect to the galaxy population, assessing issues such as the fraction of (blue) galaxies as a function of the scale of the cosmic web pattern and its caustic features. We find that the galaxy properties form a continuum in the scale-space cosmic web. Intimately coupled to the hierarchical build-up of the cosmic structure, it also allows us to systematically assess the impact of the formation time of the various structural components of the cosmic web on the galaxy properties. This furthers insight into the establishment of the observed colour-density relation of galaxies.

A key feature of close-in, multiple super-Earth (SE) systems is the tendency for adjacent planet pairs to lie just wide of low-order mean-motion resonances (MMR). This period ratio distribution has motivated numerous theoretical studies, particularly those invoking post-disk processes that perturb initially resonant architectures. We investigate whether orbital instability among cold Jupiters (CJs) can perturb inner SE systems initially in MMR. We show that a single pericenter passage of a highly eccentric CJ can disrupt inner resonances once a critical perturbation strength is exceeded, increasing the libration amplitude of the resonant angles. However, N-body simulations show that deep penetration of CJs into the inner system is uncommon, with $\lesssim 10-20\%$ of cases reaching $\lesssim 10\%$ of the initial semi-major axis of the innermost CJ. Motivated by these results, we use secular perturbation theory to quantify the impact of time-dependent forcing from scattering CJs on the eccentricity and resonant-angle evolution of inner SEs. We find that for typical systems (e.g., with SEs at $\sim 0.1$ au and CJs at a few au), such forcing can efficiently disrupt resonances, driving resonance-angle circulation in most systems ($\gtrsim 60\%$ for 2:1 and $\sim 85\%$ for 3:2 configurations). Thus, even when the "final" CJ has little effect on the "current" SEs, its earlier scattering history can leave significant imprints on the system architecture. This mechanism, and similar ones involving more abundant cold Neptunes, provide a natural source of dynamical "kicks" and offer a pathway for producing the observed trough-peak structure in the period ratio distribution of Kepler multi-planet systems.

The proposed GaiaNIR mission would extend Gaia's astrometric capabilities into the near-infrared, improving astrometric precision and enabling observations in heavily dust-obscured regions. In this work, we investigate the impact of GaiaNIR on the detectability of dark matter halos in globular clusters by comparing its performance with that of Gaia. Expected observations from future Gaia data releases and GaiaNIR are modeled for a globular cluster with properties similar to M4. The cluster is simulated with a range of dark matter halo sizes and varying levels of extinction, allowing a direct assessment of each mission's ability to detect and distinguish dark matter halos across different extinction conditions. To support this comparison, the relationship between the Gaia G band and several near-infrared bands is examined. We find that Gaia can resolve extended dark matter halos in low-extinction conditions, but its performance degrades significantly as extinction increases. In contrast, GaiaNIR reduces statistical uncertainties and retains sensitivity to extended halos even with strong extinction. These results indicate that GaiaNIR would both strengthen constraints on kinematic signatures accessible to Gaia and enable the study of clusters in heavily obscured regions that are currently beyond Gaia's reach.

Exoplanet surveys have revealed a wide diversity of planetary systems, requiring integrated models of planet formation to explain their origin. Planet population synthesis (PPS) modelling is a key tool for linking theory with the statistical properties of observed exoplanets. In the coming decade, the number of known exoplanets is expected to increase ten-fold, with a significant expansion in the range of planetary parameters probed by upcoming missions. We aim to develop a new PPS model capable of predicting planetary masses, radii, orbits, and atmospheric properties across diverse stellar hosts, while maintaining high computational efficiency for statistical comparison with observations. We build upon our previous model, which included water enrichment of primordial atmospheres via magma-gas interactions, and extend it by incorporating a semi-analytical treatment of post-disc dynamical evolution in multiplanet systems. Additional updates include revised prescriptions for disc evolution, resonance trapping, and atmospheric escape. The updated model produces planetary distributions that differ from our previous results, particularly in the abundance of Earth- and sub-Earth-mass planets. These differences arise mainly from the new dynamical evolution model and show improved agreement with simulations based on direct N-body integrations. Atmospheric enrichment is also found to strongly influence both the occurrence of gas giants and the radius distribution of close-in super-Earths and sub-Neptunes. The upgraded model provides a computationally efficient and physically comprehensive framework for predicting planetary populations across a wide range of stellar environments, enabling large parameter surveys and robust statistical comparisons with observations.

Modeling the Milky Way stellar halo requires well-determined density and velocity anisotropy profiles. However, it has been challenging to gather a large sample of stars with six-dimensional data that extend beyond 40 kpc to map the outer halo. Our work investigates the velocity anisotropy in the Milky Way stellar halo with more than 10,000 blue horizontal-branch stars, combining Gaia astrometric data and spectroscopic data from SEGUE, DESI and LAMOST. This large sample allows us to obtain a detailed profile of up to $\sim$70 kpc. Radial velocities are predominant in the inner halo ($< 30$ kpc), and the anisotropy presents a smooth decrease before rapidly dropping to negative values, becoming dominated by tangential dispersion velocities. Removing the main known accreted structures of the Milky Way, makes the anisotropy profile radially-dominated at all radii. Our profile clearly shows an increase in the anisotropy from the center of the Galaxy, in accordance to the simulations. We also investigate the correlation of anisotropy with metallicity and with color. The lack of correlation between metallicity and anisotropy in our clean sample reinforces that this relation is driven by merger events. The initial exploration with color indicates a relation between kinematics and age, showing that older stars are dynamically colder and present less radial orbits than younger stars in the inner halo.

We screen and analyze exoplanet candidates around A-type stars (defined as Teff between 7500 and 10,000 K) observed by the Transiting Exoplanet Survey Satellite to evaluate their likelihood of being genuine exoplanets. Our analysis involves transit signal searches, light-curve detrending, estimation of nearby-source contamination, and calculation of false-positive probabilities (FPPs). Among the 18 candidates analyzed, four exhibit relatively low FPP values (<15%). Two candidates are excluded from further analysis due to the lack of stellar parameter data. Six candidates show no clearly detectable transit signals, likely due to shallow or weak features, while six candidates exhibit relatively high FPP values, leaving their authenticity uncertain. Among the four low-FPP targets, two-TIC 48031665 and TIC 259230140-stand out as the most promising. TIC 48031665 shows a very shallow transit signal but has a very low FPP and minimal nearby starlight contamination. TIC 259230140 displays a clear U-shaped transit light curve typical of planetary transits, along with slightly higher yet still low FPP and contamination levels. These two objects are therefore considered the most promising candidates identified in this study.

The atmospheres of hot rocky exoplanets are among the first primary targets of the JWST. Interpreting their atmospheric spectra requires understanding the link between silicate lava compositions and overlying atmospheres. We investigate the sensitivity of simulated emission spectra of dry lava planets to variations in oxide abundances in silicate melt. Our goal is to determine which molten surface features could be distinguishable with future observations. We combine our vaporisation code with gas chemical equilibrium and radiative transfer codes to self-consistently compute atmospheric chemistry and thermal structure. Alongside varying lava compositions, we assess the impact of host star spectral type on emission spectra. TiO2 melt abundance dictates atmospheric TiO, which strongly influences surface temperature and emission spectra due to its short-wave opacity. This creates a degeneracy with heat redistribution efficiency, potentially broken by observing the optical TiO emission feature. Atmospheric SiO and SiO2 abundances depend on melt SiO2 content, with stronger SiO and SiO2 emission features at higher melt abundances. For the currently best observable HREs, changes in TiO2 and SiO2 abundance of about an order of magnitude with respect to BSE, could potentially be observable with 12 JWST eclipse observations.

The Milky Way (MW) hosts a central bar whose pattern speed, orientation, and length remain uncertain, largely due to observational biases and selection effects, despite the transformative data provided by the Gaia mission. We aim to reassess the MW bar properties using Gaia DR3, explicitly accounting for incompleteness and astrometric uncertainties, and to quantify the expected improvements from future Gaia DR4, DR5, and GaiaNIR data. We combine Gaia DR3 RGB samples with line-of-sight velocities and realistic Gaia and GaiaNIR mock catalogues to characterise observational biases. We then apply standard techniques to infer the bar pattern speed and structural properties, and evaluate their performance for upcoming data releases. Using Gaia DR3 RGB mock catalogues, we find that the bar pattern speed exhibits a systematic offset of $+14.4 \pm 2.3$ km$~$s$^{-1}~$kpc$^{-1}$. Applying this approach to the data yields $\Omega_p = 43.7 \pm 0.1$ km$~$s$^{-1}~$kpc$^{-1}$, which we interpret as a conservative upper limit. Correcting for this bias gives $\Omega_p = 29.3 \pm 2.3$ km$~$s$^{-1}~$kpc$^{-1}$, although this estimate should be treated with caution given the limited number of mock realizations. We also detect bisymmetric perturbations in $v_\phi$ and $\langle |v_R / v_{\rm tot}| \rangle$, with phase angles $\phi_b = 19$-$24^\circ$ in the bar region. Future Gaia data releases, together with GaiaNIR, are expected to reduce systematic offsets in the pattern speed to $\sim +5$ km$~$s$^{-1}~$kpc$^{-1}$. In addition, GaiaNIR will further improve proper motion precision to below $0.001$ mas$~$yr$^{-1}$ for bright sources and extend the spatial coverage. Our results indicate that current measurements of the MW bar pattern speed are significantly affected by systematics, but that forthcoming Gaia and GaiaNIR data will substantially improve both accuracy and robustness.

Extended, low surface brightness emission has been identified in a number of protoplanetary disks, in tension with predictions of radial drift theory. We aim to investigate the nature and origin of faint, extended dust emission in the outer regions of protoplanetary disks, which we define as the Halo, using multiwavelength (sub-)millimeter continuum observations of three systems: Elias 2-24, IM Lup, and DM Tau. We utilize Atacama Large Millimeter Array (ALMA) observations of our targets to perform spectral energy distribution (SED) fitting with four dust compositions and, derive radial profiles of their dust properties. The halos identified in our sources account for 20 - 30% of the total flux density at (sub-)millimeter wavelengths. In Elias 2-24, IM Lup, and DM Tau, we infer maximum grain sizes of 2 cm, $<$ 4 mm, and $<$ 9 mm, with the data best reproduced by porous amorphous carbon, compact amorphous carbon, and compact organic carbon compositions respectively. Their total dust masses are $125^{+34}_{-23}$, $301^{+139}_{-101}$, and $829^{+761}_{-378}$ M$_{\oplus}$, with corresponding halo masses of $33^{+12}_{-6}$, $103^{+25}_{-17}$, and $316^{+202}_{-117}$ M$_{\oplus}$. The halos of IM Lup and DM Tau are dust rich with gas-to-dust mass ratios of 64 and 18 respectively. In all three disks, the dust drift and growth timescales are shorter than the disk ages, implying that the smooth outer disks should not exist. The halos in our sources hold relevant fractions of the total dust reservoir, demonstrating that they play an important role in alleviating the mass-budget problem. While the persistence of halos in IM Lup and DM Tau could be explained by late infall, the presence of cm-sized grains in Elias 2-24's halo suggests that hidden pressure traps also play a role.

Large scale magnetic fields in galaxy clusters can influence their physics and the evolution of the cluster galaxies. These properties remain poorly constrained due to a historical lack of high-sensitivity and high-resolution spectro-polarimetric data. Thanks to the advent of the SKA pathfinders and precursors this is now dramatically changing. By exploiting the densest RM grid produced to date with broadband spectro-polarimetric data in the context of the MeerKAT Fornax Survey and presented in a previous paper (508 sources over 6.35 deg$^2$), we aim to study in detail the Fornax cluster's magnetic field. We compare the RM grid properties with numerical simulations to constrain the strength and the structure of the intra-cluster magnetic field. We model the magnetic field power spectrum with a power-law and we find a slope of $\sim$2.7 fluctuating between $\sim$1 and $\sim$15 kpc. It has a central strength of $\sim$5$\mu$G decreasing with the thermal plasma density according to a power-law exponent of $\sim$1.6, the highest value to date in large scale systems. By analysing a sample of 17 galaxy clusters and groups with magnetic field estimates from the literature, we observe larger auto-correlation lengths in the case of massive merging clusters and lower values for relaxed clusters and low-mass systems. We also observe a systematic increase of the central magnetic field strength as a function of central density, $B_0\propto n_0^{0.38}$. Finally, we argue that the steepening of the Fornax cluster's magnetic field profile and its relatively high central strength could be indicative of a recent re-amplification at the centre due to the extended central radio galaxy. The sample analysis supports the proposed scenario, although more detailed magnetic field studies conducted using consistent modelling on larger samples are needed to better understand magnetisation in clusters and groups.

We present a new public-domain MOlecular Fitting Analysis Tool (MOFAT) designed to probe molecule-forming regions in supernovae (SNe) through analysis of molecular features in the near- and mid-infrared. MOFAT employs a novel data-driven approach to explore the physical properties of these regions using time-independent radiative transfer simulations that include multidimensional, clump-like structures, constrained by high-precision observations. Such structures are required to reproduce the flux ratio between fundamental and overtone bands, overcoming limitations of traditional one-zone forward-modeling, such as optical-depth effects and initial configurations. Our approach enables spectral fits that can reconstruct overall abundances and temperatures and determine parameterized small-scale structures associated with physical instabilities. We systematically study the relationship between physical parameters and the profiles of CO and SiO, showing that free parameters are constrained, while detection of small-scale structure requires optically thick bands. As a demonstration, MOFAT is applied to SN2024ggi at +285 and +385 days post-explosion. We find that CO formation triggers SiO formation in the inner layers of the CO-rich region previously studied. The inner edge of the SiO-emitting region recedes from velocities of v1 from 1500 to 1000 km/s, indicating continued SiO formation. The SiO mass decreases from about (2-6)E-3 Mo by roughly an order of magnitude, suggesting ongoing evaporation. SiO features indicate clumping, but most of the flux originates from optically thin regions. SiO contributes negligibly to cooling, and we find no evidence for dust formation. Finally, we discuss observational strategies to trace the evolution of molecule formation and its connection to dust formation.

Our ongoing spectroscopic survey of faint planetary-nebula nuclei (PNNi) has revealed 30 new hydrogen-deficient central stars. The majority of them (21) belong to the PG1159 spectral class (having He-C-O-dominated atmospheres). They increase the number of known PN central stars of this type from 25 to 46. Our spectral analysis finds that their effective temperatures are high (T$_{\rm eff}$ = 110,000 - 180,000 K), locating them in the GW Vir pulsational instability strip. Future photometric observations should therefore substantially increase the number of known PNN pulsators (currently, it is nine). We found six new members of the O(He) spectral type (with He-dominated atmospheres; T$_{\rm eff}$ = 120,000 - 150,000 K), tripling the number of known PNNi of this class. Finally, we identified three hot helium-rich white dwarfs with traces of carbon and/or nitrogen (spectral type DOZ; T$_{\rm eff}$ = 70,000 - 100,000 K). They are the first objects of this spectral class found to be associated with a planetary nebula.

Traditional galaxy-galaxy lensing is a well-established method of probing the statistical properties of the Universe's matter and galaxy distribution. However, this measure does not carry all the statistical information, provided the matter and galaxy distribution contain non-Gaussian features. In order to study these non-Gaussianities, it is necessary to consider higher-order statistical measures. The aim of this work is to extend the analytical basis describing the statistical correlations between galaxies and shear to the fourth order, with special emphasis on the associated aperture statistics. In order to include fourth-order statistics in future analysis of the relation between mass and galaxies, we further investigate whether we can expect to detect these statistics from observations of stage IV surveys. We define the four-point correlation function (4PCF) between the shear and the positions of triplets of foreground galaxies and derive its relation to the respective trispectrum. We convert the 4PCF to aperture statistics and derive the analytical form of the respective filter function, which we then implement in a numerical integration pipeline. Furthermore, we develop a direct estimator that allows us to measure galaxy-mass aperture moments of arbitrary order on pixelized data using a Fast-Fourier-Transform (FFT) algorithm. We show that the corresponding aperture measure $\langle\mathcal{N}^3 M_\mathrm{ap}\rangle$ can be calculated with sub-percent accuracy on relevant aperture scales, $\theta$, by means of numerical integration. Furthermore, we apply the FFT-based direct estimator to a mock catalog with a realistic stage IV survey setup on a sky area of $2000~\mathrm{deg}^2$, and detect the connected part of the aperture statistics $\langle\mathcal{N}^3 M_\mathrm{ap}\rangle(\theta)$ with a signal-to-noise ratio of roughly nine on small aperture scales.

The outer Galaxy presents an optimal setting for investigating molecular clouds and star formation in environments with low metallicity. A total of 72 Galactic edge clouds were surveyed using the CO\,(2--1) line with the IRAM\,30\,m telescope, leading to the identification of 112 CO clumps within molecular clouds with linear resolutions of 0.5--0.9\,pc. Parameters such as size, mass, surface density, and velocity dispersion of these CO clumps, derived from CO\,(2--1) observations, exhibit ranges of 0.6--3.4\,pc, 34--8250\,M$_\odot$, 12--1025\,M$_{\odot}$\,pc$^{-2}$, and 0.3--1.7\,km\,s$^{-1}$, respectively. Over the Galactocentric distance range of 14--23\,kpc, no systematic variations are found in these parameters. The velocity dispersion-size relationship of the Galactic edge clumps is modeled as $\sigma_{\rm v}$\,=\,0.69($\pm$0.03)$R_{\rm eff}^{0.36(\pm0.10)}$, indicating that turbulence is present within the Galactic edge clumps, akin to observations in the inner Galactic disk clouds. Furthermore, the luminous mass-size relation of the Galactic edge clumps is described by $M_{\rm lum}$\,=\,196($\pm$17)$R_{\rm eff}^{\,2.18\,(\pm0.26)}$, suggesting the average column density remains almost constant for clouds of different sizes. The virial parameters range from 0.6 to 15.3, with a median value of 2.8\,$\pm$\,0.6, suggesting that most clumps are gravitationally unbound. Furthermore, the virial parameters of our Galactic edge clumps show a decreasing trend with increasing Galactocentric distances, described by an exponential relation $\alpha_{\rm vir}$\,=\,33.0($\pm$\,10.4)\,e$^{-R_{\rm g}/6.7(\pm0.9)}$, consistent with previous results.

We report on an eight year survey of simultaneous optical and radar meteor detections with the goal of isolating the fraction of meteors missed by specular radars. A total of 10,503 Electron Multiplied Charge Couple Device (EMCCD) meteors with peak brightness above +7 were simultaneously detected by the Canadian Meteor Orbit Radar (CMOR) and used to estimate the fraction of radar echoes missed as a function of speed and height. During the time period that our cameras were recording, we found some 34,119 and 18,008 meteor echoes in total occurred within the field of view of the EMCCD cameras at 29 and 38 MHz respectively. This demonstrated that a significant fraction of the specular radar echoes remain below the detection threshold of the EMCCD cameras. We used these data to derive corrections for radar-specific observing biases. The optical height distributions for six velocity bins, spanning 10 - 72 km/s were used to determine the fraction of potential radar echoes which are observed for meteors with higher begin heights ($k_c$>96) and for those with lower begin heights. When compared to the correction factors currently used in calculating shower fluxes with CMOR, mid-velocity showers such as the Geminids and South Delta Aquariids are found to have been overcorrected, while high velocity showers like the Perseids and Leonids are significantly undercorrected.

Using time-distance helioseismology applied to 14-years of SDO/HMI observations spanning solar cycle 24 and rising phase of cycle 25, we present evidence that meridional flows in the lower half of the near-surface shear layer (NSSL), modulated by active-region magnetic fields, play a central role in the episodic global transport of magnetic flux. In particular, polar field buildup is tightly linked to plasma outflows diverging from active latitudes within the deeper NSSL. The magnitude and timing of hemispheric polar field evolution are regulated by depth-dependent meridional flow, including its cross-equatorial component, responding to active-region flux asymmetries. During cycle 24 maximum, stronger southern outflows accelerated flux transport, causing the southern polar field to peak nearly four years before the northern. Global magnetic flux transport patterns in the previous three solar cycles (21, 22, and 23) show broad consistency with the deeper meridional flow modulation inferred in cycles 24 and 25. These results identify activity-dependent flow variations in deeper layers of the NSSL as a dynamically significant component of the Babcock-Leighton process that governs the generation and hemispheric asymmetry of global dipole field.

We present NOEMA3D, a unique high-resolution study of purely molecular gas kinematics at $z \sim 1.1$ to 1.6, providing a dedicated view of cold gas dynamics at the late stages of the peak epoch of cosmic star formation. Using deep ($gtrsim 20$ hr on source per target) IRAM-NOEMA CO observations of 10 massive ($10.45 < log(M^*/M_\odot) < 11.43$) ) main-sequence galaxies, complemented by high-resolution JWST imaging, we resolve the molecular gas kinematics and morphology on kiloparsec scales. We find that all galaxies exhibit ordered rotation with moderate intrinsic turbulence (median $\sigma_0 \sim 32 \pm 10$ km/s, median $V_c/\sigma_0 \sim 8.6 \pm 2.9$), consistent with dynamically turbulent disks at late cosmic noon. After modeling the axisymmetric rotation with the forward-modeling code DysmalPy, we reveal spatially coherent velocity residuals in all but one more inclined system. The inferred in-plane non circular motions reach amplitudes of $\sim 50$-100 km/s, significantly larger than typically observed in local disk galaxies. Interpreting these non-circular motions as radial flows we find that the velocity residuals spatially coincide with non-axisymmetric structures -- spiral arms and bars -- demonstrating a direct link between galaxy morphology and gas transport at $z \sim 1$-2. In spiral galaxies, the residual velocity patterns are typically dominated by inflows, while barred systems display an apparent inflow-outflow pattern, characteristic of in-plane bar-driven gas motions. We further find that the inferred molecular gas inflow rates are substantial, with a typical net inflow rate of the order of the star formation rate ( $\dot M \sim -50 M_\odot/$yr). This implies that spiral arms and bars at cosmic noon are highly efficient at funneling cold gas toward galaxy centers, perhaps driving the buildup of bulges and feeding central star forming regions and supermassive black holes.

We present a spatially resolved study of cold molecular gas and dust in ten main-sequence galaxies at z=1.1-1.6, using observations of CO(4-3), CO(3-2), [C I](1-0), and dust continuum from the NOEMA3D survey. We find a widely presence of spatially extended molecular gas and dust, with sizes comparable to those of the stellar disk, in contrast to those of central-dominated starburst galaxies at similar redshifts. While various molecular gas tracers generally exhibit similar spatial distributions, the CO line (J=3-2 or J=4-3) remain the most effective for mapping molecular gas distribution and kinematics. In addition, the spatially resolved correlations between different molecular gas tracers exhibit about two times larger scatter than their galactic-integrated correlations, indicating that interstellar medium (ISM) conditions already deviate from global averages on scales of 3-6 kpc, likely reflecting the clumpy or inhomogeneous ISM in cosmic noon star-forming galaxies. Within our sample, both the molecular gas fraction and its depletion time are nearly constant across the galactic disks out to 2 Re, supporting a global linear Kennicutt-Schmidt law. The presence of extended molecular gas disks, along with regular stellar structures, small central bulges, and ordered cold gas kinematics, supports the idea that the evolution of main-sequence disk galaxies at cosmic noon is driven by steady gas accretion and transport through prominent spiral arms and/or bars. This process stands in contrast to the merger-driven stochastic gas accretion in compact starbursts.

We present a statistical census of the Na D-traced neutral interstellar medium (ISM) and outflows in 309 galaxies at $0.6<z<4$ using JWST/NIRSpec medium-resolution grating spectroscopy from the SMILES, JADES, Blue Jay, and Aurora surveys. After subtracting the stellar continuum, we model the Na D $\lambda\lambda 5890, 5896$ Åand detect neutral ISM absorption in 76 galaxies. Of the Na D-traced ISM detections, 85\% are found in massive galaxies ($\log(M_*/M_\odot)>10$), and only 15\% in lower-mass systems. In the massive regime, ISM absorption is seen in both star-forming and quiescent galaxies, whereas in lower-mass systems it is observed only in star-forming galaxies. In massive quiescent galaxies, Na D detectability appears linked to star formation history: it is preferentially detected in older systems with larger 4000 Åbreaks, as well as younger, rapidly quenching galaxies with strong Balmer absorption H$\delta_A$. We identify Na D outflows in 26 galaxies, revealing a possible dichotomy in their driving mechanisms between star-forming and quiescent galaxies. In star-forming galaxies, outflow properties correlate with star-formation properties, consistent with a star-formation-driven origin. In quiescent galaxies, however, outflows are not associated with residual star formation and often require more energy than such star formation can provide. Together with the high AGN fraction among outflow-detected quiescent galaxies, this suggests that AGN dominate Na D-traced neutral outflows in cosmic noon quiescent systems. We further identify five quiescent galaxies with possible AGN fossil outflows, suggesting that AGN-driven outflows can persist beyond the active accretion phase and may help maintain quiescence.

We present a method to estimate non-Gaussian power spectrum covariance matrices by directly measuring the response of the small-scale power spectrum to long-wavelength perturbations via bispectrum and trispectrum estimators. Specifically, we derive estimators for the complete non-Gaussian matter power spectrum covariance, including the super-sample contribution, in terms of the squeezed bispectrum and collapsed trispectrum of the underlying density field. We apply these estimators to the Quijote simulations, and recover unbiased estimates of the small-scale ($k\gtrsim 0.15~h/{\rm Mpc}$) matter power spectrum covariance at the percent level using only 25 simulations - comparable to the precision of the sample covariance estimated using 5,000 simulations. This technique significantly reduces the number of simulations needed to estimate power spectrum covariances and opens the possibility of inferring power spectrum covariances directly from survey data, enabling stringent tests of simulations and, potentially, power spectrum analyses that do not rely on external covariance matrices.

Simulations of the transitional flow in Taylor-Couette configuration are carried out to study the effect of the gap width on turbulent transition. The research results show that, under the same radius and the rotating speed of the inner cylinder, as the gap width increases, the flow becomes more stable. It is discovered that the average velocity distribution in the gap approaches the free vortex flow as the width increase and the stability of the flow is enhanced. It is found that, as the gap width increases, the maximum of the energy gradient function (from the energy gradient theory) in the gap decreases, which delays the turbulent transition. As such, the larger the gap width, the later the transition occurs. As the gap width increases, the Reynolds number based on the gap width alone is not able to characterize the flow behavior in Taylor-Couette flows, and the effect of the radius ratio should be taken into account.

Satellite constellations are transforming space systems from isolated spacecraft into networked, software-defined platforms capable of on-orbit perception, decision making, and adaptation. Yet much of the existing AI studies remains centered on single-satellite inference, while constellation-scale autonomy introduces fundamentally new algorithmic requirements: learning and coordination under dynamic inter-satellite connectivity, strict SWaP-C limits, radiation-induced faults, non-IID data, concept drift, and safety-critical operational constraints. This survey consolidates the emerging field of on-orbit space AI through three complementary paradigms: (i) {federated learning} for cross-satellite training, personalization, and secure aggregation; (ii) {multi-agent algorithms} for cooperative planning, resource allocation, scheduling, formation control, and collision avoidance; and (iii) {collaborative sensing and distributed inference} for multi-satellite fusion, tracking, split/early-exit inference, and cross-layer co-design with constellation networking. We provide a system-level view and a taxonomy that unifies collaboration architectures, temporal mechanisms, and trust models. To support community development and keep this review actionable over time, we continuously curate relevant papers and resources at this https URL.

We investigate electroweak baryogenesis from domain walls with electroweak-symmetric cores moving through the electroweak-broken plasma. In the thick-wall regime, CP-violating semiclassical forces generate chiral asymmetries that source baryon number through transport and weak sphaleron processes. We show that the baryon yield is governed by the hierarchy between the wall width, the CP-violating source width, and the diffusion length, and we identify the corresponding scaling behavior in the relevant parametric limits. A distinctive feature of this mechanism is the interference between the two faces of the domain wall, which leads to qualitatively different behavior for CP-violating sources that are even or odd under wall-orientation reversal. We construct a simplified description that captures these effects and reproduces the predictions of the full transport system in a broad range of parameter space. Applying our framework to a singlet-extended Standard Model, we delineate the region in which electroweak-symmetric domain walls can generate the observed baryon asymmetry.

We explore what may be deduced about the neutrino mass ordering problem from the observation of core-collapse supernova burst neutrinos in modern terrestrial detectors. We employ ternary plots in a novel way to visualize the time evolution of the flavor composition of various supernova neutrino flux models from the SNEWPY software package. Through our analysis of several models using a simplified unfolding process, we have explored potential robust discriminants between the normal and inverted mass orderings. We find that the normal and inverted mass orderings tend to occupy different regions in ternary space across different models.

Kinetic Alfven waves (KAWs) are fundamental to energy transport and small-scale structure formation in the turbulent, magnetized interstellar medium (ISM). While first-order Korteweg--de Vries (KdV) models describe weakly nonlinear KAW solitons, they fail in strongly inhomogeneous environments where higher-order effects become significant. We investigate higher-order "dressed" kinetic Alfven (KA) solitons in a structured ISM (warm ionized medium, H II regions, stellar-wind bubbles, supernova remnants). Using a multi-component fluid model with superthermal electrons, we derive an inhomogeneous KdV-type equation with cubic nonlinearity, nonlinear-dispersive cross terms, and fifth-order dispersion. The dressed soliton has a $\operatorname{sech}^2$ core decorated by higher-order corrections. We classify soliton morphologies across the Galactic plane as a function of electron suprathermality $\kappa_e$. Five classes ($\psi_{\rm I}$--$\psi_{\rm V}$) evolve non-monotonically with $\kappa_e$: strongly suprathermal ($\kappa_e=1.6$) favour negative double-hump ($\psi_{\rm III}$); intermediate $\kappa_e$ produce layered sequences of $\psi_{\rm II}$, $\psi_{\rm I}$, $\psi_{\rm IV}$, $\psi_{\rm V}$; near-Maxwellian ($\kappa_e=3.1$) revert to KdV-like $\psi_{\rm I}$. Localised $\psi_{\rm V}$ appear as a red ring around the SWB shell and a red core inside the SNR, showing embedded structures actively generate distinct morphologies. First-order KdV theory is insufficient; dressed solitons are the natural nonlinear states. The ISM morphology selects soliton class by modulating leading vs. higher-order terms. $\psi_{\rm V}$ features link macroscopic ISM structures to kinetic-scale fluctuations, offering candidates for extreme scattering events and pulsar scintillation. The non-monotonic $\kappa_e$ dependence can constrain electron suprathermality from observations.

We study the hydrodynamics of the Filtered Dark Matter (Filtered DM) scenario during a first-order phase transition (FOPT). In this scenario, the bubble wall is highly reflective of the dark matter (DM) fluid but transparent to radiation, making the hydrodynamic problem fundamentally different from that of the electroweak FOPT. Motivated by this property, we formulate the hydrodynamics of this system as a two-component fluid composed of DM and radiation, and find that the solutions can be classified into detonation-like and deflagration-like branches in the ballistic regime and in the local thermal equilibrium (LTE) regime. In the ballistic regime, the energy--momentum of DM that cannot enter the wall appears as a reflected mode, while in the LTE regime, it relaxes into the energy--momentum of radiation. We find that this difference in the fate of the DM fluid that cannot enter the interior of the wall leads to different hydrodynamic behaviors in the DM and radiation fluids independently and, in particular, results in different existence conditions for solutions in the deflagration-like branch. Based on these results, we further revisit the impact of hydrodynamic effects on the relic abundance of Filtered DM and demonstrate the change in the abundance induced by hydrodynamic effects. In addition, we also discuss the non-conservation of the entropy current from the viewpoint of the two-fluid system, and briefly comment on the similarity between the Filtered DM system and information-thermodynamic systems.

In a recently proposed approach to testing models of inflation by Cosmic Microwave Background (CMB) radiation the reheating temperature is directly expressed in terms of the CMB observables. Its model independent bounds translate in a given model into narrow ranges of those observables. In that approach we analyse the polynomial class of the $\alpha$-attractor inflaton potential models (P-models), in a broad range of polynomials and with the inflaton decays and fragmentation in the reheating period taken into account. The predictions for the CMB observables, the scalar spectral index $n_s$ and tensor-to-scalar ratio $r$, are compared with the Planck and Planck combined with ACT data. Both can be accommodated by that class of the $\alpha$ attractor models. The sensitivity of the results of that comparison to the reheating temperature and to the upper bound on the ratio $r$ is clearly demonstrated.

These notes give a concise introduction to General Relativity at the advanced undergraduate level, starting from the weak field limit and gravitational waves, then introducing curved manifolds and Riemannian geometry. The nonlinear gravitational action is used to derive the nonlinear field equations, with applications to black holes and cosmology. It is assumed that special relativity and electromagnetic waves have been previously studied. Some advanced topics such as Rindler and Hawking radiation are derived, and recent developments in gravitational wave detection are briefly covered. Problems are included, both those suitable for homework, and simpler ones that could be worked out by students during class sessions.

We present an effective numerical method that can be used to straightforwardly calculate the full spectrum of primordial gravitational waves produced during inflation and reheating. Our method is based on the Bogoliubov approach with several key improvements to overcome its shortcomings such as numerical instabilities at high frequencies and issues with tachyonic modes. We also present a few useful analytical examples from which one can gain crucial insights into the numerical instabilities. The improved method allows us to demonstrate that anharmonicity of inflaton oscillations can leave interesting fingerprints on the high-frequency part of the GW spectrum. Our numerical code is publicly available on [GitHub](We present an effective numerical method that can be used to straightforwardly calculate the full spectrum of primordial gravitational waves produced during inflation and reheating. Our method is based on the Bogoliubov approach with several key improvements to overcome its shortcomings such as numerical instabilities at high frequencies and issues with tachyonic modes. We also present a few useful analytical examples from which one can gain crucial insights into the numerical instabilities. The improved method allows us to demonstrate that anharmonicity of inflaton oscillations can leave interesting fingerprints on the high-frequency part of the GW spectrum. Our numerical code is publicly available on GitHub this https URL.

We study finite-window black-hole spectroscopy in the loud-event regime and ask when a multimode ringdown fit supports a stable common-remnant Kerr interpretation. Starting from whitened, tapered detector-frame data, we prove a deterministic frequency-extraction theorem for a projected sampled Prony--matrix-pencil pipeline with explicit statistical, algorithmic, omitted-tail, and mismatch terms. We then construct a local inverse atlas for the Kerr $(\ell,m,n)=(2,2,0)$ map on an event-local detector-frame remnant box for GW250114 and propagate the resulting primary uncertainty into $(2,2,1)$ and $(4,4,0)$ consistency tests. These ingredients yield a detector-frame trust criterion for individual windows. We calibrate mismatch and colored-noise radii on a GW250114-like synthetic waveform bank built from public surrogate, CCE, and numerical-relativity information, and we apply the resulting bounds to the public H1/L1 strain and public parameter-estimation products for GW250114. The accepted windows form an intermediate post-peak band: earlier windows remain sensitive to start-time drift and structured nuisance fits, whereas later windows become variance dominated. Within that band, the recovered remnant remains consistent with the public inspiral--merger--ringdown estimates and supports a common-remnant Kerr interpretation that survives the full preprocessing and robustness checks. For loud events, the relevant question is therefore which finite detector-frame windows sustain spectroscopy, not whether some multimode fit can be made in isolation.

We investigate the thermodynamic and phenomenological implications of a cosmological model governed by fractional entropy applied to the apparent horizon of a flat Friedmann-Lemaître-Robertson-Walker (FLRW) universe. By utilizing the unified first law of thermodynamics alongside the Kodama-Hayward temperature, we derive a generalized set of Friedmann equations characterized by a fractional parameter $\alpha \in (1,2]$. The thermodynamic analysis reveals that the specific heats $C_V$ and $C_p$ share the same sign and depend solely on the deceleration parameter, demonstrating that the fractional model is thermodynamically stable during the late-time accelerated expansion and does not exhibit phase transitions. To constrain the background dynamics, we confront the truncated fractional model with a joint sample of late-time observational data, including Cosmic Chronometers, Pantheon+SH0ES supernovae, and the latest DESI DR2 Baryon Acoustic Oscillations. Exploring the physically motivated range $ 1 < \alpha \leq 2 $, we find that the fit quality degrades monotonically as $\alpha$ decreases from the General Relativity limit, with the data favoring $\alpha$ close to $2$ while yielding $H_0 = 69.50 \pm 0.42$ km/s/Mpc and $\Omega_{m0} = 0.292 \pm 0.008 $ at $\alpha = 2$. Decreasing $\alpha$ coherently shifts $H_0$ upward and $\Omega_{m0} $ downward, revealing that the fractional parameter modulates the background expansion in a physically nontrivial and observationally distinguishable way.

Inferring electric potentials from electron phase space density measurements in the lunar wake is complicated by two challenges: the asymmetry between the sunward and anti-sunward sides of the wake driven by the solar wind strahl, and the presence of ion acoustic shocks in the central wake. We develop the Hamiltonian inversion method, which infers the full spatial electric potential profile by exploiting the quasi-static Vlasov equilibrium condition $f = f(H)$, where $H$ is the electron Hamiltonian. The method addresses both challenges through a domain-decomposition strategy: on the two sides of the wake the potential is inferred independently by minimizing the misfit between the observed phase space density and a self-consistently reconstructed $f_\mathrm{interp}(\tilde{H})$, while in the central wake where flat-top trapped electron distributions are present the potential is inferred directly from the flat-top width. We validate the method against particle-in-cell simulation data at two evolutionary stages of the lunar wake: an early stage where strahl asymmetry is strong but no shocks have formed, and a later stage where ion acoustic shocks and flat-top distributions are present. We then apply the method to two ARTEMIS lunar wake crossings at the same evolutionary stages, inferring normalized potential drops of $e\Delta\varphi/T_e \sim 15$ and $\sim 5$ respectively and capturing shock-associated potential enhancements in the central wake. The method is broadly applicable to plasma environments where electrons are in quasi-static equilibrium with a field-aligned electric potential.

\texttt{gwNRHME} is a framework that converts multi-modal (i.e., containing several spherical harmonic modes) quasi-circular waveforms into their eccentric counterparts, provided the quadrupolar eccentric mode is known, by exploiting universal eccentric modulation functions. Leveraging this framework, we combine the quasi-circular NR surrogate model \texttt{NRHybSur3dq8} with the quadrupolar, non-spinning, eccentric surrogate \texttt{NRSurE\_q4NoSpin\_22} to construct a multi-modal, non-spinning, eccentric model, denoted as \model{}, which includes nine modes: $(2,\{1,2\})$, $(3,\{1,2,3\})$, $(4,\{2,3,4\})$, and $(5,5)$. When compared against 156 eccentric SXS NR waveforms, \model{} achieves median frequency-domain mismatches (computed using the Advanced LIGO design sensitivity) of $\sim 9\times 10^{-5}$, with a standard deviation of $\sim 2 \times 10^{-4}$. To demonstrate the modularity of the framework, we further combine \texttt{NRSurE\_q4NoSpin\_22} with effective-one-body (EOB) models \texttt{SEOBNRv5HM} and \texttt{TEOBResumS-Dali} in their non-spinning limits, yielding eccentric waveforms with median mismatches of $\sim 2\times10^{-4}$ and $\sim 10^{-3}$, respectively, with standard deviation of $\sim 2 \times 10^{-3}$ and $\sim 2 \times 10^{-2}$ respectively. Finally, we provide both a surrogate model, \texttt{gwEccEvolve\_q4NoSpin\_Sur}, and an analytical model, \texttt{gwEccEvNSv2}, for the eccentricity evolution up to $2M$ before merger, based on eccentricity definitions derived from the universal modulation functions. The \texttt{gwNRHME} framework is publicly available through the \texttt{gwModels} package, and the resulting waveform models will be released via the \texttt{gwsurrogate} package.

Astrophysical dark matter particles with masses well below GeV-scale can be difficult to detect using conventional nuclear recoil experiments due to their low velocities in our Milky Way halo. Elastic scattering with high-energy cosmic rays or thermal production inside core-collapse supernovae can accelerate sub-GeV DM to (semi-)relativistic velocities, producing nuclear recoil energies above the keV threshold that paleo-detectors can record over geological timescales. Using olivine as the target with 100$\,$g$\cdot$Gyr exposure, we compute track length distributions from such (semi-)relativistic dark matter fluxes, incorporating all major backgrounds (neutrinos, uranium-chain neutrons, thorium recoils) with a statistical analysis on an Asimov dataset. We derive 95 C.L. projected sensitivity of paleo-detectors to the DM-nucleon cross section for dark matter masses between a few MeV and hundreds of MeV. Our results show that paleo-detectors are able to probe large parameter regions that are not covered by current and near-future experiments designed to detect dark matter and neutrinos. In particular, paleo-detectors offer a unique ability to record the dark matter flux from Galactic supernova events over geological times. Such cumulative exposure enables sensitivity gains of a few orders of magnitude compared to conventional experiments.

We compare the correlation functions of inflationary perturbations computed either with quantum or classical dynamics. Even if they are enforced to agree at a specific time during inflation, classical and quantum correlations will differ at the end of inflation, provided that interactions are relevant. The difference between the results of the classical and quantum computations is exponentially sensitive to the number of e-folds elapsed from the time of agreement. We illustrate this finding with the tree-level bispectrum of the primordial curvature fluctuation and the one-loop power spectrum of tensor modes. We also show that classical evolution from a finite time does not imply the appearance of poles in the scalar bispectrum.

Measuring field-aligned currents (FACs) using magnetic field observations provides a powerful means to probe the multi-scale interactions between the magnetosphere, ionosphere and thermosphere. In this study, we apply the curlometer technique to Swarm spacecraft observations and to simulations of the coupled magnetosphere-ionosphere system. We begin by correlating current density curlometer estimates derived from Swarm tetrahedra with varying spatial scales and barycentre locations. This confirms an apparent departure from stationarity for FACs at spatio-temporal scales below 100 km where measurements appear highly uncorrelated. We then analyse simulated magnetic perturbations, where true four-point measurements are available. This shows how, even at meso-scales of hundreds of kilometres, time-shifted FAC estimates can diverge significantly from this ground truth. In both observational and simulated data we find poor tetrahedral configurations can produce spurious perpendicular currents due to numerical instability in the inversion process. This can be mitigated using appropriate quality metrics and high-quality FAC reconstructions still achieved with a tetrahedral face well-aligned to the local magnetic field. These results highlight the dynamic nature of FACs at large as well as small scales, and underscore the substantial advantages of true four-point observations for their accurate analysis.