Papers for Friday, Mar 14 2025

JWST has made several surprising discoveries, underscored by the `too early' appearance of well-formed galaxies and supermassive black holes. It recently also uncovered a compact galaxy (JWST-ER1g) associated with a complete Einstein ring (JWST-ER1r) at photometric redshift $z_l=1.94^{+0.13}_{-0.17}$, produced by a lensed galaxy at $z_s=2.98^{+0.42}_{-0.47}$. In two independent studies, this system ($M_{\rm lens}\sim 6.5\times 10^{11}\;M_\odot$) has yielded different conclusions concerning whether or not it requires an unexpected contribution of mass from sources other than stars and fiducial dark matter. The different redshift inferred by these two analysis for the lensed galaxy appears to be the culprit. In this paper, we examine the impact of the background cosmology on our interpretation of the JWST data. We compare the measured characteristics of JWST-ER1 in flat-$\Lambda$CDM with those emerging in the context of $R_{\rm h}=ct$. We show that, unlike the latter model's mitigation of the tension created by JWST's other discoveries, neither cosmology is favored by this particular Einstein ring. The disparity is common to both models, leaving open the question of whether a new type of mass, or a modified initial mass function, may be present in this source.

We implement frequency-dependent antenna responses and develop likelihood classes (standard likelihood, multibanded likelihood, and the relative binning (RB) likelihood) capable of handling the same within the framework of \texttt{Bilby}. We validate the approximate likelihoods by comparing them with the exact likelihood for a GW170817-like signal (signal-to-noise ratio ~ 1900) containing higher-order modes of radiation. We use the relative-binning likelihood to perform parameter estimation (PE) for a GW170817-like signal, including Earth-rotation effects, detector-size effects, and higher-order modes. We study the system in several detector networks consisting of a single 40 km Cosmic Explorer, a 20 km CE and a present-generation detector at A+ sensitivity. The PE runs with RB take around a day to complete on a typical cluster.

Adaptive Mesh Refinement (AMR) with subcycling in time enables different grid levels to advance using their own time steps, ensuring finer grids employ smaller steps for accuracy while coarser grids take larger steps to improve computational efficiency. We present the development, validation, and performance analysis of a subcycling in time algorithm implemented within the CarpetX driver in the Einstein Toolkit framework. This new approach significantly improves upon the previous subcycling implementation in the Carpet driver by achieving higher-order convergence -- fourth order in time instead of second order -- and enhanced scaling performance. The key innovation lies in optimizing the exchange of ghost points at refinement boundaries, limiting it to the same number as those at inter-process boundaries using dense output from coarser levels, thereby reducing computational and communication overhead compared to the implementation in Carpet, which required a larger number of buffer zones. To validate the algorithm, we first demonstrate its fourth-order convergence using a scalar wave test. We then apply the algorithm to binary black hole (BBH) simulations, confirming its robustness and accuracy in a realistic astrophysical scenario. The results show excellent agreement with the well-established LazEv code. Scaling tests on CPU (Frontera) and GPU (Vista) clusters reveal significant performance gains, with the new implementation achieving improved speed and scalability compared to the Carpet-based version.

Recent high-resolution solar observations have unveiled the presence of small-scale loop-like structures in the lower solar atmosphere, often referred to as unresolved fine structures, low-lying loops, and miniature hot loops. These structures undergo rapid changes within minutes, and their formation mechanism has remained elusive. In this study, we conducted a comprehensive analysis of two small loops utilizing data from the Interface Region Imaging Spectrograph (IRIS), the Goode Solar Telescope (GST) at Big Bear Solar Observatory, and the Atmospheric Imaging Assembly (AIA) and the Helioseismic Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO), aiming to elucidate the underlying process behind their formation. The GST observations revealed that these loops, with lengths of $\sim$3.5 Mm and heights of $\sim$1 Mm, manifest as bright emission structures in H$\alpha$ wing images, particularly prominent in the red wing. IRIS observations showcased these loops in 1330 angstrom slit-jaw images, with TR and chromospheric line spectra exhibiting significant enhancement and broadening above the loops, indicative of plasmoid-mediated reconnection during their formation. Additionally, we observed upward-erupting jets above these loops across various passbands. Furthermore, differential emission measurement analysis reveals an enhanced emission measure at the location of these loops, suggesting the presence of plasma exceeding 1 MK. Based on our observations, we propose that these loops and associated jets align with the minifilament eruption model. Our findings suggest a unified mechanism governing the formation of small-scale loops and jets akin to larger-scale X-ray jets.

I show that the small differences between the orbital parameters of the dark comet 2005 VL1 and the Venera 2 spacecraft (reported in arXiv:2503.07972) are of the magnitude expected from gravitational deflection by a close encounter of Venera 2 with Venus.

The Spitzer Survey of Stellar Structure in Galaxies (S$^4$G), together with its Early Type Galaxy (ETG) extension, stand as the most extensive dataset of deep, uniform mid-infrared (mid-IR; 3.6 and 4.5$\,\mu$m) imaging for a sample of $2817$ nearby ($d<40 \,$Mpc) galaxies. However, the velocity criterion used to select the original sample results in an additional 422 galaxies without HI detection that ought to have been included in the S$^4$G on the basis of their optical recession velocities. In order to create a complete magnitude-, size- and volume-limited sample of nearby galaxies, we collect $3.6\,\mu$m and $i$-band images using archival data from different surveys and complement it with new observations for the missing galaxies. We denote the sample of these additional galaxies as Disc Galaxy (DG) extension. We present the Complete Spitzer Survey of Stellar Structure in Galaxies (CS$^4$G), encompassing a sample of $3239$ galaxies with consistent imaging, surface brightness profiles, photometric parameters, and revised morphological classification. Following the original strategy of the S$^4$G survey, we produce masks, surface brightness profiles, and curves of growth using masked $3.6\,\mu$m and $i$-band images. From these profiles, we derive the integrated quantities: total magnitude, stellar mass, concentration parameter, and galaxy size, converting to $3.6\,\mu$m. We re-measure these parameters also for the S$^4$G and ETG to create a homogenous sample. We present new morphological revised $T$-types, and we showcase mid-IR scaling relations for the photometric parameters. We complete the S$^4$G sample by incorporating 422 galaxies. The CS$^4$G includes at least 99.94\% of the complete sample of nearby galaxies, meeting the original selection criteria, and it will enable a wide set of investigations into galaxy structure and evolution.

Faint $\gamma$-ray signatures emerge in Fermi-LAT data stacked scaled to the characteristic $R_{500}$ radii of MCXC galaxy clusters. This third paper in a series shows a $4.3\sigma$ excess of discrete 4FGL-DR4 catalog $\gamma$-ray sources at the $r<1.5R_{500}$ radii of 205 clusters, coincident with an $r\sim R_{500}$ diffuse $2.6\sigma$ excess of 1-100 GeV emission from 75 high-latitude clusters. The source excess becomes highly ($>5\sigma$) significant when considering the substantial ($3.4\sigma$) and unexpectedly rapid quenching of $\gamma$-ray sources just inside the virial shock. The excess sources show radial, spectral, and luminosity distributions better matching radio-relic counterparts or substructure than present tentative classifications as blazar-candidates. Their spectral distribution is bimodal: flat-spectrum sources are consistent with enhanced hadronic emission behind weak, Mach $\sim2$ shocks, while softer sources may be phoenix counterparts.

The stellar companions in the binary black hole systems Gaia BH2 and BH3, both of which are $\alpha$-enhanced red giant branch stars, are expected to show normal modes with the characteristic signature of convectively-driven solar-like oscillations. We investigate this using photometry from the TESS mission and find such a signal for Gaia BH2. For Gaia BH2, we measure a power excess frequency of $\nu_{\rm max}=60.15\pm0.57$ $\mu$Hz and a large separation of $\Delta\nu=5.99\pm0.03$ $\mu$Hz, yielding a mass of $1.19^{+0.08}_{-0.08}$ M$_\odot$, which is in agreement with spectroscopically derived parameters. Seismic modeling favors an age for the red giant of $5.03^{+2.58}_{-3.05}$ Gyr, strongly suggesting that it is a young, $\alpha$-enriched giant star, which are thought to arise from a binary accretion or merger scenario. Ground-based photometry of Gaia BH2 spanning 8 years indicates a photometric period of $398\pm5$ d, which we tentatively attribute to rotation. If this rotation is physical, it can not be explained solely by evolutionary spin-down or magnetic braking, and implies that the red giant underwent some tidal forcing mechanism. Suggestively, this period is close to the pseudo-synchronous spin period of P$_\text{spin}=428\pm1$ days derived from the binary orbit. For Gaia BH3, we are unable to identify an asteroseismic signal in the TESS data despite predicting that the amplitude of the signal should lie well above the measured noise level. We discuss a number of scenarios for why this signal may not be visible.

We present a new parametric strong lensing analysis of the galaxy cluster MACS J0138.0-2155 at z = 0.336, the first known to show two multiply-imaged supernova (SN) siblings, SN Requiem and SN Encore at z= 1.949. We exploit HST and JWST multiband imaging in synergy with new MUSE spectroscopy to develop an improved lens mass model. We include 84 cluster members (of which ~60% are spectroscopically confirmed) and two perturber galaxies along the line of sight. Our observables consist of 23 spectroscopically confirmed multiple images from 8 background sources, spanning a fairly wide redshift range, from 0.767 to 3.420. To accurately characterise the sub-halo mass component, we calibrate the Faber-Jackson scaling relation based on the stellar kinematics of 14 bright cluster galaxies. We build several lens models, with different cluster total mass parametrisations, to assess the statistical and systematic uncertainties on the predicted values of the position and magnification of the observed and future multiple images of SN Requiem and SN Encore. Our reference best-fit lens model reproduces the observed positions of the multiple images with a root-mean-square offset of 0".36, and the multiple image positions of the SNe and their host galaxy with a remarkable mean precision of only 0".05. We measure a projected total mass of $M(<60~ \rm kpc) = 2.89_{-0.03}^{+0.04} \times 10^{13} M_{\odot}$, consistent with that independently derived from the Chandra X-ray analysis. We demonstrate the reliability of the new lens model by reconstructing the extended surface-brightness distribution of the multiple images of the host galaxy. The discrepancy between our model-predicted magnification values with those from previous studies, critical for understanding the intrinsic properties of the SNe and their host galaxy, underscores the need to combine cutting-edge observations with detailed lens modelling.

The full range of conditions under which rocky planets can host atmospheres remains poorly understood, especially in the regime of close-in orbits around late-type stars. One way to assess the presence of atmospheres on rocky exoplanets is to measure their dayside emission as they are eclipsed by their host stars. Here, we present Spitzer observations of the 4.5 $\mu$m secondary eclipses of the rocky super-Earth TOI-431 b, whose mass and radius indicate an Earth-like bulk composition (3.07 $\pm$ 0.35 M$_{\oplus}$, 1.28 $\pm$ 0.04 R$_{\oplus}$). Exposed to more than 2000 times the irradiation of Earth, dayside temperatures of up to 2400K are expected if the planet is a dark bare-rock without a significant atmosphere. Intriguingly, despite the strong stellar insolation, we measure a secondary eclipse depth of only 33 $\pm$ 22 ppm, which corresponds to a dayside brightness temperature of $1520_{-390}^{+360}$K. This notably low eclipse depth disagrees with the dark bare-rock scenario at the 2.5$\sigma$ level, and suggests either that the planet is surrounded by an atmosphere, or that it is a bare-rock with a highly reflective surface. In the atmosphere scenario, the low dayside emission implies the efficient redistribution of heat to the nightside, or by molecular absorption in the 4-5 $\mu$m bandpass. In the bare-rock scenario, a surface composition made of a high-albedo mineral species such as ultramafic rock can lead to reduced thermal emission consistent with low eclipse depth measurement. Follow-up spectroscopic observations with the James Webb Space Telescope hold the key to constraining the nature of the planet.

We introduce a novel approach to detecting microlensing events and other transients in light curves, utilising the isolation forest (iForest) algorithm for anomaly detection. Focusing on the Legacy Survey of Space and Time by the Vera C. Rubin Observatory, we show that an iForest trained on signal-less light curves can efficiently identify microlensing events by different types of dark objects and binaries, as well as variable stars. We further show that the iForest has real-time applicability through a drip-feed analysis, demonstrating its potential as a valuable tool for LSST alert brokers to efficiently prioritise and classify transient candidates for follow-up observations.

In the most precise distance ladder determination of $H_0$, the observed near-infrared (NIR) fluxes of Cepheids are corrected for dust, assuming that the extinction law in large, star-forming spiral hosts of Type Ia supernovae (SN Ia) is similar to the Milky Way's average value of $R_V \approx 3.1$. Intriguingly, studies of SNe Ia often point to lower values for their hosts ($R_V \sim 2$). Ambiguities related to $R_V$ may limit future efforts to measure $H_0$ beyond $\sim 1\%$ precision. To better resolve extragalactic extinction laws, we directly measure the wavelength-dependent absorption of background galaxies seen in HST and JWST images (0.5--2.7 $\mu$m). We take the following steps: (i) subtract foreground stars to measure accurate photometry of background galaxies with a tool, $\texttt{SPHOT}$; (ii) measure their redshifts and spectroscopic features with Keck/DEIMOS; (iii) determine their intrinsic spectral energy distributions from the empirical templates which match the absorption lines and breaks in observed spectroscopic features, and (iv) measure $R_V$ by fitting the extinction model to the difference between the template and the observed SEDs. The above steps are tested with artificial datasets to insure they accurately recover the input $R_V$. We apply this set of steps to a first case, NGC 5584, a SN Ia host and a calibrator of the Hubble constant. The estimated value of $R_V$ for NGC 5584, $R_V=3.59^{+0.99}_{-0.62}(\text{stat})\pm0.19(\text{syst})$, is consistent with the MW-like extinction law, and it is $\gtrsim 3.5\sigma$ away from $R_V=2$ as favored by SN Ia. If additional hosts show similar results, it would suggest that SN Ia extinction may not be solely due to mean interstellar dust. We are now undertaking a statistical study of 5-10 SH0ES hosts to determine the distribution of host extinction laws.

Globular Clusters (GCs) are known to host distinct stellar populations, characterized by different chemical compositions. Despite extensive research, the origin of these populations remains elusive. According to many formation scenarios, the second population (2P) originated within a compact and denser region embedded in a more extended first population (1P) system. As a result, 2P binaries should be disrupted at a larger rate than 1P binaries. For this reason, binary systems offer valuable insight into the environments in which these stellar populations formed and evolved. In this research, we analyze the fraction of binaries among 1P and 2P M dwarfs in the outer region of NGC 288 using Hubble Space Telescope data. We combine our results with those from a previous work, where we inferred the fraction of 1P and 2P binaries in the cluster center. In the outer region, we find a predominance of 1P binaries ($97^{+1}_{-3}\%$) compared to 2P binaries ($3\pm1\%$) corresponding to an incidence of binaries with a mass ratio (i.e., the ratio between the masses of the primary and secondary star) greater than 0.5 equal to $6.4\pm 1.7\%$ for the 1P population and $0.3\pm 0.2\%$ for the 2P population. These binary fractions and incidences differ from those found in the cluster$'$s central region, where the 1P and 2P populations exhibit similar binary incidences and fractions. These results are in general agreement with the predictions of simulations following the evolution of binary stars in multiple-population GCs, starting with a dense 2P subsystem concentrated in the central regions of a 1P system.

We present Shamrock, a performance portable framework developed in C++17 with the SYCL programming standard, tailored for numerical astrophysics on Exascale architectures. The core of Shamrock is an accelerated parallel tree with negligible construction time, whose efficiency is based on binary algebra. The Smoothed Particle Hydrodynamics algorithm of the Phantom code is implemented in Shamrock. On-the-fly tree construction circumvents the necessity for extensive data communications. In tests displaying a uniform density with global timesteping with tens of billions of particles, Shamrock completes a single time step in a few seconds using over the thousand of GPUs of a super-computer. This corresponds to processing billions of particles per second, with tens of millions of particles per GPU. The parallel efficiency across the entire cluster is larger than $\sim 90\%$.

We present the first joint analysis of the power spectrum and bispectrum using the Data Release 1 (DR1) of the Dark Energy Spectroscopic Instrument (DESI), focusing on Luminous Red Galaxies (LRGs) and quasars (QSOs) across a redshift range of $0.4\leq z\leq2.1$. By combining the two- and three-point statistics, we are able to partially break the degeneracy between the logarithmic growth rate, $f(z)$, and the amplitude of dark matter fluctuations, $\sigma_\textrm{s8}(z)$, which cannot be measured separately in analyses that only involve the power spectrum. In comparison with the (fiducial) Planck $\Lambda$CDM cosmology we obtain $f/f^\textrm{fid}=\{0.888_{-0.089}^{+0.186},0.977_{-0.220}^{+0.182},1.030_{-0.085}^{+0.368}\}$, $\sigma_{s8}/\sigma^\textrm{fid}_\textrm{s8}=\{1.224_{-0.133}^{+0.091},1.071_{-0.163}^{+0.278},1.000_{-0.223}^{+0.088}\}$ respectively for the three LRG redshift bins, corresponding to a cumulative 10.1\% constraint on $f$, and of 8.4\% on $\sigma_\textrm{s8}$, including the systematic error budget. The cumulative constraints for the ShapeFit compressed parameters from our joint power spectrum-bispectrum analysis are respectively $\sigma_{\alpha_\textrm{iso}}=0.9\%$ (9\% improvement with respect to our power spectrum-only analysis); $\sigma_{\alpha_\textrm{AP}}=2.3\%$ (no improvement with respect to power spectrum-only analysis, which is expected given that the bispectrum monopole has no significant anisotropic signal); $\sigma_{f\sigma_\textrm{s8}}=5.1\%$ (9\% improvement); $\sigma_{m+n}=2.3\%$ (11\% improvement). These results are fully consistent with the main DESI power spectrum analysis, demonstrating the robustness of the DESI cosmological constraints, and compatible with Planck $\Lambda$CDM cosmology.

The strongly lensed Supernova (SN) Encore at a redshift of $z = 1.949$, discovered behind the galaxy cluster MACS J0138$-$2155 at $z=0.336$, provides a rare opportunity for time-delay cosmography and studies of the SN host galaxy, where previously another SN, called SN Requiem, had appeared. To enable these studies, we combine new James Webb Space Telescope (JWST) imaging, archival Hubble Space Telescope (HST) imaging, and new Very Large Telescope (VLT) spectroscopic data to construct state-of-the-art lens mass models that are composed of cluster dark-matter (DM) halos and galaxies. We determine the photometric and structural parameters of the galaxies across six JWST and five HST filters. We use the color-magnitude and color-color relations of spectroscopically-confirmed cluster members to select additional cluster members, identifying a total of 84 galaxies belonging to the galaxy cluster. We construct seven different mass models using a variety of DM halo mass profiles, and explore both multi-plane and approximate single-plane lens models. As constraints, we use the observed positions of 23 multiple images from eight multiply lensed sources at four distinct spectroscopic redshifts. In addition, we use stellar velocity dispersion measurements to obtain priors on the galaxy mass distributions. We find that six of the seven models fit well to the observed image positions. Mass models with cored-isothermal DM profiles fit well to the observations, whereas the mass model with a Navarro-Frenk-White cluster DM profile has an image-position $\chi^2$ value that is four times higher. We build our ultimate model by combining four multi-lens-plane mass models and predict the image positions and magnifications of SN Encore and SN Requiem. Our work lays the foundation for building state-of-the-art mass models of the cluster for future cosmological analysis and SN host galaxy studies.

We present a population synthesis model which addresses the different mass distributions of the metal-polluted and non-metal-polluted hydrogen-atmosphere white dwarfs identified in volume-limited samples. Specifically, metal-pollution has been observed to be rare in white dwarfs more massive than $\approx$0.7 $M_{\odot}$. Our population synthesis model invokes episodic accretion of planetary debris onto a synthetic population of white dwarfs. We find that the observed difference can be explained in the regime where most debris disks last for $10^4$$-$$10^6$ years. This is broadly consistent with observational estimates that disk lifetimes are on the order 10$^5$$-$10$^7$ years. We also invoke an alternate model which explores an upper limit on planetary system formation and survival around the intermediate-mass progenitors of the more massive white dwarfs. In this scenario, we find an upper limit on the polluted white dwarf mass of $M_{\rm wd}<0.72^{+0.07}_{-0.03}$ M$_{\odot}$. This implies an empirical maximum progenitor mass of $M_{\rm ZAMS}^{\rm max}=2.9^{+0.7}_{-0.3}$ M$_{\odot}$. This value is consistent with the maximum reliable host star mass of currently known exoplanet systems. We conclude by imposing these two results on the sample of He-atmosphere white dwarfs within 40\,pc. We find that both scenarios are capable of providing a consistent solution to the full sample of H- and He-atmosphere white dwarfs.

The Sun's open-closed flux boundary (OCB) separates closed and open magnetic field lines, and is the site for interchange magnetic reconnection processes thought to be linked to the origin of the slow solar wind (SSW). We analyse the global magnetic field structure and OCB from December 2010 to December 2019 using three coronal magnetic field models: a potential field source surface (PFSS) model, a static equilibrium magnetofrictional model, and a time-dependent magnetofrictional model. We analyse the model and cycle dependence of the OCB length on the photosphere, as well as the magnetic flux in the vicinity of the OCB. Near solar maximum, the coronal magnetic field for each model consists predominantly of long, narrow coronal holes, and nearly all the open flux lies within one supergranule-diameter (25 Mm) of the OCB. By comparing to interplanetary scintillation measurements of SSW speeds, we argue that the fraction of open flux within this 25 Mm band is a good predictor of the amount of SSW in the heliosphere. Importantly, despite its simplicity, we show that the PFSS model estimates this fraction as well as the time-dependent model. We discuss the implications of our results for understanding SSW origins and interchange reconnection at the OCB.

This thesis investigates the evolution of galaxies in diverse environments, utilizing Sloan Digital Sky Survey (SDSS) data to explore the impact of environmental richness on central and satellite galaxies across stellar mass ranges, compared to isolated systems. The sample is limited to 0.03 < z < 0.1 and apparent magnitudes brighter than 17.78, ensuring spectroscopic completeness and reliable stellar population estimates. Galaxies are categorized by environment as field or cluster/group systems, with further separation into satellites and centrals. By analyzing the star formation rate (SFR)-stellar mass plane, this work identifies systematic differences in the blue cloud (BC), green valley (GV), and red sequence (RS) across environments. Morphological and stellar population analyses reveal that T-type, metallicity, and stellar age transitions highlight the role of environmental quenching. A newly introduced T-Type \emph{vs.} specific SFR diagram provides evidence that morphological transformation precedes full quenching. Correlating galaxy properties with time since infall through projected phase space confirms the delayed-then-rapid quenching model for low- and intermediate-mass galaxies, extending it to morphology. Time-scales for quenching and morphological transitions are also derived as a function of stellar mass.

The next generation of galaxy surveys will provide highly precise measurements of galaxy clustering, therefore requiring a corresponding accuracy. Current approaches, which rely on approximations and idealized assumptions, may fall short in capturing the level of detail required for high-precision observations. In order to increase the modeling accuracy, recently, unequal-time contributions to the galaxy power spectrum have been introduced in order to include the effects of radial correlations. We present a generalization of the formalism for the observed unequal-time power spectrum, that includes Doppler and local general relativistic corrections, plus local primordial non-Gaussianity. We find that unequal time corrections can potentially mimic an effective $f_{\mathrm{NL}}$ of order unity. We provide a first assessment of the significance of unequal-time corrections for future galaxy clustering experiments, estimating a Signal-to-Noise-Ratio of $\sim3$ for Stage IV-like surveys.

The Standard Model of cosmology, $\Lambda$CDM, while enormously successful, is currently unable to account for several cosmological anomalies the most prominent of which are in the measurements of the Hubble parameter and $S_8$. Additionally, the inclusion of the cosmological constant is theoretically unappealing. This has lead to extensions of the model such as the use of fluid equations for interacting dark matter and dark energy which, however, are ad hoc since they do not appear to arise from a Lagrangian. Recently, we have proposed $\mathcal{Q}_{\rm CDM}$ as an alternative to $\Lambda$CDM which is a dynamical model of a quintessence field interacting with dark matter within a field theoretic approach. In this approach, we analyze the effect of the dark matter mass, the dark matter-dark energy interaction strength and the dark matter self-interaction on the cosmological parameters. Further, within $\mathcal{Q}_{\rm CDM}$ we investigate the possible alleviation of the Hubble tension and the $S_8$ anomaly and the nature of dark energy.

Radiowave Observations on the Lunar Surface of the photo-Electron Sheath instrument (ROLSES- 1) onboard the Intuitive Machines' Odysseus lunar lander represents NASA's first radio telescope on the Moon, and the first United States spacecraft landing on the lunar surface in five decades. Despite a host of challenges, ROLSES-1 managed to collect a small amount of data over fractions of one day during cruise phase and two days on the lunar surface with four monopole stacer antennas that were in a non-ideal deployment. All antennas recorded shortwave radio transmissions breaking through the Earth's ionosphere -- or terrestrial technosignatures -- from spectral and raw waveform data. These technosignatures appear to be modulated by density fluctuations in the Earth's ionosphere and could be used as markers when searching for extraterrestrial intelligence from habitable exoplanets. After data reduction and marshaling a host of statistical and sampling techniques, five minutes of raw waveforms from the least noisy antenna were used to generate covariances constraining both the antenna parameters and the amplitude of the low-frequency isotropic galactic spectrum. ROLSES- 2 and LuSEE-Night, both lunar radio telescopes launching later in the decade, will have significant upgrades from ROLSES-1 and will be set to take unprecedented measurements of the low-frequency sky, lunar surface, and constrain the cosmological 21-cm signal. ROLSES-1 represents a trailblazer for lunar radio telescopes, and many of the statistical tools and data reduction techniques presented in this work will be invaluable for upcoming lunar radio telescope missions.

We present updated constraints on modified gravity by including the Integrated Sachs-Wolfe (ISW) effect from CMB lensing-CMB temperature cross-correlations, based on the latest Planck PR4 maps. Utilizing the Effective Field Theory of dark energy approach and adopting the $w_0w_a$CDM background cosmological model, we find that including the CMB ISW lensing cross-correlations tighten constraints on the modified gravity parameters by approximately $20\%$, reducing the viable parameter space by $50$-$80\%$. We derive constraints from Planck CMB, Planck and ACT CMB lensing, DESI DR1 BAO, CMB ISW-lensing, and type Ia supernovae (SN Ia) data. Our results are consistent with General Relativity (GR) at the $95\%$ CL. The modified gravity model shows a mild preference for an evolving dark energy at the $1.8\sigma$, $2.6\sigma$ and $3.2\sigma$ levels for the combinations with Pantheon+, Union3 and DESY5 supernova datasets. We find that using the latest likelihoods $\texttt{HiLLiPoP}+\texttt{LoLLiPoP}$ alleviates the departure of modified gravity parameters from the GR-values compared to results using Planck 2018 data. This paper underlines the importance of the ISW lensing probe in constraining late-time modifications of gravity.

Titan, Saturn's largest satellite, maintains an atmosphere composed primarily of nitrogen (N$_2$) and methane (CH$_4$) that leads to a complex organic chemistry. Some of the nitriles (CN-bearing organics) on Titan are known to have substantially enhanced $^{15}$N abundances compared to Earth and to Titan's dominant nitrogen (N$_2$) reservoir. The $^{14}$N/$^{15}$N isotopic ratio in Titan's nitriles can provide better constraints on the synthesis of nitrogen-bearing organics in planetary atmospheres as well as insights into the origin of Titan's large nitrogen abundance. Using high signal-to-noise ratio ($>13$), disk-integrated observations obtained with the Atacama Large Millimeter/submillimeter Array (ALMA) Band 6 receiver (211-275 GHz), we measure the $^{14}$N/$^{15}$N and $^{12}$C/$^{13}$C isotopic ratios of acetonitrile (CH$_3$CN) in Titan's stratosphere. Using the Nonlinear optimal Estimator for MultivariatE spectral analySIS (NEMESIS), we derived the CH$_3$CN/$^{13}$CH$_3$CN ratio to be 89.2 $\pm$ 7.0 and the CH$_3$CN/CH$_3$$^{13}$CN ratio to be 91.2 $\pm$ 6.0, in agreement with the $^{12}$C/$^{13}$C ratio in Titan's methane, and other Solar System species. We found the $^{14}$N/$^{15}$N isotopic ratio to be 68.9 $\pm$ 4.2, consistent with previously derived values for HCN and HC$_3$N, confirming an enhanced $^{15}$N abundance in Titan's nitriles compared with the bulk atmospheric N$_2$ value of $^{14}$N/$^{15}$N = 168, in agreement with chemical models incorporating isotope-selective photodissociation of N$_2$ at high altitudes.

We report the detection of [C I] $^3P_1$--$^3P_0$ emission in the nearby galaxy NGC 7679 using the Atacama Compact Array (ACA) of the Atacama Large Millimeter/submillimeter Array (ALMA). In Michiyama et al. (2021), [C I] $^3P_1$--$^3P_0$ emission in NGC 7679 was reported as undetected based on ACA observations conducted in 2019 (ALMA Cycle 6). These observations had ~1 minute on-source time and used a single pointing with a field of view (FoV) of ~20 arcsec. In 2023 (Cycle 9), we carried out mosaic observations using seven pointings with an FoV of ~27 arcsec and 4-5 minutes on-source per pointing. The additional data have significantly improved the line sensitivity, uv-sampling, and noise uniformity across the galaxy disk. Our Cycle 9 observations confirm the presence of extended [C I] $^3P_1$--$^3P_0$ emission in NGC 7679, which was completely missed in the Cycle 6 observations due to insufficient sensitivity and uv-sampling. This highlights the basic technical challenges of estimating the total flux by interferometric observations with sparse uv-sampling.

We perform individual weak-lensing (WL) mass measurements for 78 eROSITA's first All-Sky Survey (eRASS1) clusters in the footprint of Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) S19A, without any priors of the eRASS1 X-ray quantities or assumption of the mass and concentration relation. In the sample, we find 3 clusters are mis-associated with optical counterparts and 12 clusters are poorly fitted with an NFW profile. The average mass for the 12 poor-fit clusters changes from $\sim 10^{14}h_{70}^{-1}M_\odot$ to $\sim 2\times 10^{13}h_{70}^{-1}M_\odot$ when lensing contamination from surrounding mass structures is taken into account. The scaling relations between the true mass and cluster richness and X-ray count-rate agree well with the results of the eRASS1 Western Galactic Hemisphere region based on count-rate-inferred masses, which are calibrated with the HSC-SSP, DES, and KiDS surveys. We develop a Bayesian framework for inferring the mass-concentration relation of the cluster sample, explicitly incorporating the effects of weak-lensing mass calibration in the mass-concentration parameter space. The redshift-dependent mass and concentration relation is in excellent agreement with predictions of dark-matter-only numerical simulations and previous studies using X-ray-selected clusters. Based on the two-dimensional (2D) WL analysis, the offsets between the WL-determined centers and the X-ray centroids for 36 eRASS1 clusters with high WL S/N are described by two Gaussian components. We find that the mis-centering effect with X-ray centroids is smaller than that with peaks in the galaxy maps. The projected halo ellipticity is $\langle \varepsilon \rangle=0.45$ at $M_{200}\sim 4\times10^{14}h_{70}^{-1}M_\odot$, in agreement with results of numerical simulations and previous studies of clusters more than twice our mass.

Cosmic reionization of HI leaves enduring relics in the post-reionization intergalactic medium, potentially influencing the Lyman-$\alpha$ (Ly$\alpha$) forest down to redshifts as low as $z \approx 2$, which is the so-called ''memory of reionization'' effect. Here, we re-analyze the baryonic acoustic oscillation (BAO) measurements from Ly$\alpha$ absorption and quasar correlations using data from the extended Baryonic Oscillation Spectroscopic Survey (eBOSS) Data Release 16 (DR16), incorporating for the first time the memory of reionization in the Ly$\alpha$ forest. Three distinct scenarios of reionization timeline are considered in our analyses. We find that the recovered BAO parameters ($\alpha_\parallel$, $\alpha_\perp$) remain consistent with the original eBOSS DR16 analysis. However, models incorporating reionization relics provide a better fit to the data, with a tantalizing preference for early reionization, consistent with recent findings from the James Webb Space Telescope. Furthermore, the inclusion of reionization relics significantly impacts the non-BAO parameters. For instance, we report deviations of up to $3\sigma$ in the Ly$\alpha$ redshift-space distortion parameter and $\sim7\sigma$ in the linear Ly$\alpha$ bias for the late reionization scenario. Our findings suggest that the eBOSS Ly$\alpha$ data is more accurately described by models that incorporate a broadband enhancement to the Ly$\alpha$ forest power spectrum, highlighting the importance of accounting for reionization relics in cosmological analyses.

We describe a post-processing radiative transport code for computing the spectra, the coreshift, and the surface-brightness distribution of special relativistic jets with arbitrary optical thickness. The jet consists of an electron-positron pair plasma and an electron-proton normal plasma. Electrons and positrons are relativistic and composed of thermal and nonthermal components, while protons are non-relativistic and non-radiating. The fraction of a pair plasma, as well as the fraction of a nonthermal component can be arbitrarily chosen. Only the synchrotron process is considered for emission and absorption when the radiative-transfer equation is integrated along our lines of sight. We describe a suite of test problems, and confirm the frequency dependence of the coreshift in the Konigl jet model, when the plasma is composed of nonthermal component alone. Finally, we illustrate the capabilities of the code with model calculations, demonstrating that the jet will exhibit a limb-brightened structure in general when it is energized by the rotational energy of the black hole. It is also demonstrated that such limb-brightened jets show a ring-like structure in the brightness map when we observe the jet launching region nearly face-on.

We investigated by means of MUSE/VLT observations the true size of the coronal line region (CLR) in a local sample of nine active galactic nuclei known for displaying prominent coronal emission. Our analysis show that the CLR is extended from several hundred parsecs to a few kiloparsecs in the lines of [Fe VII] (IP=99 eV) and [Fe X] (IP=235 eV). In all cases, the coronal emission is closely aligned along the radio-jet axis and constrained to the limits of the [O III] ionisation cone. Besides the nuclear emission, secondary emission peaks in [Fe VII] and [Fe X] are found along the extended emission, with a shallow decrease of the line intensity with increasing distance from the AGN. Both facts suggest the action of an additional excitation mechanism besides nuclear photoionisation for the origin of the coronal gas. This is further supported by the fact that in some sources the extended coronal emission accounts for more than 50\% of the total emission and by the high degree of gas excitation in the off-nuclear region. A positive trend between the coronal line luminosity and the jet power points to shocks induced by the jet passage as the key mechanism to produce and excite this gas. We provide the first estimate of the [Fe X] coronal gas size, being in the kpc range. Our results stress the importance of the CLR as a key ingredient that should be fully considered in models trying to explain the physics of the narrow line region in AGN.

Bar structures can form internally due to the instability of their host galaxies or externally due to perturbations from other galaxies. We systematically quantify the growth timescales ($\tau_\mathrm{bar}$) of bars formed through these two mechanisms with a series of controlled $N$-body simulations. In galaxies susceptible to bar instability, tidally induced bars display $\tau_\mathrm{bar}$ values comparable to those of internally developed bars within the same disk. Tidal perturbations promote/delay bar formation by advancing/postponing its onset, but the growth rate of the bar structure remains largely unchanged. In these interaction scenarios, the bar formation is still driven primarily by the galaxy's internal nature that remains unaffected by tidal perturbations. As the external perturbation wave reaches the galaxy's center, it evokes a ''seed bar'' that is then swing amplified. In this scenario, the onset of bar formation is advanced. Conversely, bar formation may be delayed if the external perturbation wave is out of phase with the pre-existing spontaneously developed seed bar, which causes destructive interference and limits the bar growth. In the hot disk model that resists bar formation in isolation, $\tau_\mathrm{bar}$ of the tidally induced bar correlates with the strength of the perturbation. The bar growth in this model deviates from the exponential profile and is better described by a linear function. The strictly-speaking ''tidally induced bars'' may not adhere to the swing amplification mechanism that predicts an exponential bar growth. Their preference for linear growth contrasts with bars formed in galaxies inherently susceptible to bar instability.

Millinovae are a new class of transient supersoft X-ray sources with no clear signature of mass ejection. They show similar triangle shapes of $V/I$ band light curves with thousand times fainter peaks than typical classical novae. Maccarone et al. regarded the prototype millinova, ASASSN-16oh, as a dwarf nova and interpreted the supersoft X-rays to originate from an accretion belt on a white dwarf (WD). Kato et al. proposed a nova model induced by a high-rate mass-accretion during a dwarf nova outburst; the X-rays originate from the photosphere of a hydrogen-burning hot WD whereas the $V/I$ band photons are from the irradiated accretion disk. Because each peak brightness differs largely from millinova to millinova, we suspect that not all the millinova candidates host a hydrogen burning WD. Based on the light curve analysis of the classical nova KT Eri that has a bright disk, we find that the disk is more than two magnitudes brighter when the disk is irradiated by the hydrogen burning WD than when not irradiated. We present the demarcation criterion for hydrogen burning to be $I_{\rm q} - I_{\rm max} > 2.2$, where $I_q$ and $I_{\rm max}$ are the $I$ magnitudes in quiescence and at maximum light, respectively. Among many candidates, this requirement is satisfied with the two millinovae in which soft X-rays were detected.

In this study, we present a detailed analysis of public archival soft X-ray data on the classical nova V339 Delphini (Nova Del 2013) during its outburst, obtained using the {\it Chandra} High-Resolution Camera Spectrometer (HRC-S) and Low Energy Transmission Grating (LETG), as well as {\it XMM-Newton} in 2013. The observations, spanning from day 85.2 to day 112.0 after the optical maximum, capture the nova during its luminous supersoft X-ray source (SSS) phase. The spectra reveal numerous absorption features with blue-shifted velocities ranging from $\sim$ 724 to $\sim$ 1474 km s$^{-1}$, with the majority of lines blue-shifted by approximately 1200 km s$^{-1}$. We confirm the presence of a short-period modulation of the X-ray flux with a period of approximately 54 seconds, as well as the drift of this period, which was detected on days 97.0 and 112.0 during the outburst with both {\it XMM-Newton} and {\it Chandra}. This period modulation is transient in nature, with significant variations in amplitude and pulse profile over timescales of a few thousand seconds, likely due to temporary obscuration events that affect the emission from the central hot source. The pulse profiles exhibit substantial deviations from a pure sinusoidal shape, which may be related to the period drift. Additionally, the modulation amplitude shows a possible anti-correlation with the count rates on day 97.0, likely also caused by temporary obscuration events influencing the central source's emission.

In this manuscript, an oversimplified model is proposed to test the effects of intrinsic AGN variability on expected optical quasi-periodic oscillations (QPOs) related to sub-pc binary black hole systems (BBHs) in broad line AGN. The commonly accepted CAR (Continuous AutoRegressive) process is applied to describe intrinsic AGN variability related to each BH accreting system in a sub-pc BBH system. Considering obscurations related to orbital rotations with periodicity $T_p$, artificial light curves including signals for optical QPOs can be built. Then, comparing the intrinsic periodicities $T_p$ with the measured robust periodicities $T_o$ through the artificial light curves, distributions of $T_p/T_o$ have four significant peaks around 1, 2, 3 and 4, leading less than half of the artificial light curves to have consistency between $T_o$ and $T_p$. Moreover, different collected model parameters have few effects on the distributions of $T_p/T_o$, indicating the effects of intrinsic AGN variability on optical QPOs are significantly strong and stable. Furthermore, after checking properties of optical QPOs in the light curves with different time steps, there are tiny effects of time steps on optical QPOs.

At present, there is a lack of effective probes to distinguish between mid-infrared (MIR) outbursts induced by tidal disruption events (TDEs) and changing-look active galactic nuclei (CLAGNs) based on only MIR data. Here, we propose that the time variation of MIR color (K-corrected W1-W2 after subtracting the quiescent fluxes) is a promising probe. With an optically selected sample containing TDEs, ambiguous nuclear transients (ANTs), and CLAGNs, we studied the MIR color variation of their MIR counterparts using NEOWISE-R data. We found that the MIR color of TDEs and ANTs turns red faster than CLAGNs during the rising phase, and TDEs have a redder color than ANTs at the earliest phase. The former may be caused by the difference between the ultraviolet light curves of TDEs/ANTs and CLAGNs, or be related to no or relatively weak underlying AGN in TDEs/ANTs, while the latter may be related to the difference in the dust geometry. Based on color variation rate, we selected high-probability TDE, ANT, and CLAGN candidates from MIR outbursts in samples of Jiang et al. (2021) and Masterson et al. (2024). We found that both samples are mixtures of TDEs/ANTs and CLAGNs. For MIR outbursts whose hosts are not Seyfert galaxies, we estimated that $\sim50\%-80\%$ are TDEs and inferred a rate of infrared TDEs of $1.5-2.8\times10^{-5}$ galaxy$^{-1}$ yr$^{-1}$, comparable with that of optical TDEs. The rest are CLAGNs, suggesting the presence of weak AGNs that cannot be identified using common diagnoses. We predicted that with our method, a large amount of dust-obscured TDEs could be selected from future infrared surveys with higher data quality and cadence.

Galaxy formation models predict that local galaxies are surrounded by hot X-ray-emitting halos, which are technically difficult to detect due to their extended and low surface brightness nature. Previous X-ray studies have mostly focused on disk galaxies more massive than the Milky Way, with essentially no consensus on the halo X-ray properties at the lower mass end. We utilize the early-released eROSITA and archival Chandra observations to analyze the diffuse X-ray emission of NGC7793, a nearby spiral galaxy with an estimated stellar mass of only $3.2\times 10^9$ $M_{\odot}$. We find evidence for extraplanar hot gas emission from both the radial and vertical soft X-ray intensity profiles, which spreads up to a galactocentric distance of $\sim$ 6 kpc, nearly 30 $\%$ more extended than its stellar disk. Analysis of the eROSITA spectra indicates that the hot gas can be characterized by a temperature of $0.18^{+0.02}_{-0.03}$ keV, with 0.5--2 keV unabsorbed luminosity of $1.3\times 10^{38}$ erg $s^{-1}$. We compare our results with the IllustrisTNG simulations and find overall consistence on the disk scale, whereas excessive emission at large radii is predicted by TNG50. This work provides the latest detection of hot corona around a low-mass galaxy, putting new constrains on state-of-the-art cosmological simulations. We also verify the detectability of hot circumgalactic medium around even low-mass spirals with future high-resolution X-ray spectrometer such as the Hot Universe Baryon Surveyor.

This work presents GalProTE, a proof-of-concept Machine Learning model utilizing a Transformer Encoder to determine stellar age, metallicity, and dust attenuation from optical spectra. Designed for large astronomical surveys, GalProTE significantly accelerates processing while maintaining accuracy. Using the E-MILES spectral library, we construct a dataset of 111,936 diverse templates by expanding 636 simple stellar population models with varying extinction, spectral combinations, and noise modifications. This ensures robust training over 4750 to 7100 Angstrom at 2.5 Angstrom resolution. GalProTE employs four parallel attention-based encoders with varying kernel sizes to capture spectral features. On synthetic test data, it achieves a mean squared error (MSE) of 0.27% between input and predicted spectra. Validation on PHANGS-MUSE galaxies NGC4254 and NGC5068 confirms its ability to extract physical parameters efficiently, with residuals averaging -0.02% and 0.28% and standard deviations of 4.3% and 5.3%, respectively. To contextualize these results, we compare GalProTE's age, metallicity, and dust attenuation maps with pPXF, a state-of-the-art spectral fitting tool. While pPXF requires approximately 11 seconds per spectrum, GalProTE processes one in less than 4 milliseconds, offering a 2750 times speedup and consuming 68 times less power per spectrum. The strong agreement between pPXF and GalProTE highlights the potential of machine learning to enhance traditional methods, paving the way for faster, energy-efficient, and scalable analyses of galactic properties in modern surveys.

Context. Dust halos or shells, along with linear dark structures along the axes of dust tails, are commonly observed in many long-period comets near perihelion. Examples range from the recent C/2023 A3 (Tsuchinshan-ATLAS) to historical comets such as the Great Comet of 1874, C/1874 H1 (Coggia). Aims. While dust halos can readily be modeled as spin-modulated activity originating from the comet nucleus, their possible connection to those dark linear features has, to our knowledge, not been investigated. The aim of this paper is to shed light on the formation of these remarkable structures by modeling a sample of six long-period comets, using similar dust physical properties and ejection parameters, to explore whether they share a common origin. Methods. To model the dust features, we employed a Monte Carlo procedure to generate synthetic images. The particles ejected from the comet nucleus follow a power-law size distribution and are released into interplanetary space at speeds determined by the ratio of solar radiation pressure to solar gravity, the heliocentric distance, and, as a new feature of the code, the solar zenith angle at the emission point. Results. We demonstrate that, in all the cases analyzed, the dust shells form as a result of short-term events characterized by cyclically varying ejection of very small particles from large surface areas on the rotating nucleus. These events are triggered as these areas become freshly exposed to solar radiation near perihelion due to the high obliquity of the spin axes of their nuclei. The dark linear stripes along the tail axes may arise from a specific dependence of the ejection speeds on the square root of the cosine of the zenith angle, as is predicted by hydrodynamical modeling, but their presence is also dependent on the extent of the latitude region of emission that defines the velocity vector field.

We report the discovery and spectroscopic confirmation of a new bright blue Einstein ring in the Kilo Degree Survey (KiDS) footprint: the Einstein ``blue eye''. Spectroscopic data from X-Shooter at the Very Large Telescope (VLT) show that the lens is a typical early-type galaxy (ETG) at $z=0.9906$, while the background source is a Ly$\alpha$ emitter at $z=2.823$. The reference lens modeling was performed on a high-resolution $Y-$band adaptive-optics image from HAWK-I at VLT. Assuming a singular isothermal ellipsoid (SIE) total mass density profile, we inferred an Einstein radius $R_{Ein}=10.47 \pm 0.06$ kpc. The average slope of the total mass density inside the Einstein radius, as determined by a joint analysis of lensing and isotropic Jeans equations is $\gamma=2.14^{+0.06}_{-0.07}$, showing no systematic deviation from the slopes of lower redshit galaxies, This can be the evidence of ETGs developing through dry mergers plus moderate dissipationless accretion. Stellar population analysis with 8-band ($gri$ZYJHK$s$) photometries from KiDS and VIKING shows that the total stellar mass of the lens is $M*=(3.95\pm 0.35)\times 10^{11} M_\odot$ (Salpeter Initial Mass Function, IMF), implying a dark matter fraction inside the effective radius to be $f_{\rm DM}=0.307\pm 0.151$. We finally explored the dark matter halo slope and found a strong degeneracy with the dynamic stellar mass. Dark matter adiabatic contraction is needed to explain the posterior distribution of the slope, unless IMF heavier than Salpeter is assumed.

The numerical simulation of subsonic turbulence with SPH has traditionally been hindered by E0 errors, inaccurate gradient evaluations, and excessive dissipation. In this work, we present numerical results of SPH simulations of subsonic turbulence and compare to state-of-the-art codes such as AREPO and GIZMO. For the first time, SPH can reproduce the results of such codes, showing a similar interval of wavenumber in the inertial range of the Kolmogorov cascade in the subsonic regime. We use the SPH-EXA code to perform these simulations, a GPU-based state-of-the-art SPH code with high performance and extreme scalability at its core. SPH-EXA is coupled with a modern SPH solver based on methods such as an integral approach to gradient calculation, artificial viscosity switches that include a linear field cleaner, a flexible family of pairing-resistant interpolation kernels, generalized volume elements, and a controlled handling of density jumps which maximizes Lagrangian compatibility. In addition, it includes a novel and extremely scalable gravity solver for astrophysical applications.

Observational data provided by JWST instruments continue to challenge theories and models of cloud formation in sub-stellar atmospheres, requiring more sophisticated approaches in an effort to understand their spatial complexity. However, to date, most cloud microphysical models using the moment method for sub-stellar atmospheres have assumed a monodisperse size distribution, neglecting polydisperse properties. We aim to extend beyond the common assumption of a monodisperse size distribution and analyse cloud microphysical processes assuming an exponential distribution. We derive expressions for the zeroth and first moments of condensation/evaporation and collisional growth processes under the assumption of an exponential size distribution. We then compare the differences between monodisperse and exponential distribution microphysics using a simple one-dimensional (1D) column model applied to a Y-dwarf KCl cloud scenario. We find that adopting an exponential distribution modifies condensation/evaporation rates by a factor of $\approx$0.9 and collisional growth rates by factors of $\approx$1.1 (Kn $\ll$ 1) and $\approx$0.92 (Kn $\gg$ 1) for Brownian coagulation and $\approx$0.85 for gravitational coalescence, compared to the monodisperse case. In our specific test cases, we find relative differences of a maximum 10-12% in total number density and 2-3% in mean radius of the cloud particles between the monodisperse and exponential distributions. Our results offer a simple way to take into account an assumed exponential size distribution for sub-stellar atmospheric cloud microphysics using the two-moment method. In follow up studies, we will examine more complex distributions, such as the log-normal and gamma distributions, that require more than two moments to characterise self-consistently.

We conduct three-dimensional hydrodynamical simulations of core-collapse supernovae by launching several pairs of jets into a collapsing core model and show that the jittering jets explosion mechanism (JJEM) can form a point-symmetric morphology that accounts for observed morphologies of many core-collapse supernovae (CCSN) remnants. Point-symmetric morphologies are composed of pairs of opposite structures around the center of the CCSN remnant. In the JJEM, the newly born neutron star launches several to a few tens of pairs of jets with stochastically varying directions, and these jets explode the star. In the simulations with the FLASH numerical code, we launch pairs of jets with varying directions, energies, opening angles, and durations into the massive stellar core and follow their evolution for about two seconds. We show that the jets form pairs of opposite filaments, clumps, bubbles, and lobes, namely, prominent point-symmetric morphologies. The interaction of the jets with the core leads to vigorous Rayleigh-Taylor instabilities and excites many vortices, which also shape clumps and filaments. Our results strengthen the claim that the JJEM is the primary explosion mechanism of CCSNe.

Chemical abundance anomalies in twin stars have recently been considered tell-tale signs of interactions between stars and planets. While such signals are prevalent, their nature remains a subject of debate. On one hand, exoplanet formation may induce chemical depletion in host stars by locking up refractory elements. On the other hand, exoplanet engulfment can result in chemical enrichment, both processes potentially producing similar differential signals. In this study, we aim to observationally disentangle these processes by using the Ca II infrared triplet to measure the magnetic activity of 125 co-moving star pairs with high SNR, high-resolution spectra from the Magellan, Keck, and VLT telescopes. We find that co-natal star pairs in which the two stars exhibit significant chemical abundance differences also show differences in their magnetic activity, with stars depleted in refractories being magnetically more active. Furthermore, the strength of this correlation between differential chemical abundances and differential magnetic activity increases with condensation temperature. One possible explanation is that the chemical anomaly signature may be linked to planet formation, wherein refractory elements are locked into planets, and the host stars become more active due to more efficient contraction during the pre-main-sequence phase or star-planet tidal and magnetic interactions.

We study the stochastic gravitational wave background sourced by a network of cosmic superstrings and demonstrate that incorporating higher-mass string species, beyond the fundamental string, is crucial for accurately modeling the resulting gravitational wave spectrum across frequencies ranging from nanohertz to kilohertz. Using the multi-tension velocity-dependent one-scale model to evolve the cosmic superstring network, we perform several fits to the NANOGrav 15-year dataset and obtain expectation values for the fundamental string tension, string coupling and effective size of compact extra dimensions. We find that the cosmic superstring best-fits are comparable in likelihood to Supermassive Black Hole models, thought by many to be the leading candidate explanation of the signal. The implications of the best-fit spectra are discussed within the context of future gravitational wave experiments. We obtain expectation values for the fundamental string tension of $\log_{10}(G\mu_1)=-11.5^{+0.3}_{-0.3}$($-11.6^{+0.2}_{-0.3}$) for gravitational waves originating from large cuspy (kinky) cosmic superstring loops and $\log_{10}(G\mu_1)=-9.7^{+0.7}_{-0.7}$($-9.9^{+1.0}_{-0.5}$) for small cuspy (kinky) loops. We also place $2\sigma$ upper bounds on the string coupling, finding $g_s<0.65$ in all cases, and comment on the implication of our results for the effective size of the compact extra dimensions.

The Ca II resonance doublet (HK) and the near-infrared triplet (CaT) are among the strongest features in stellar spectra of FGK-type stars. These spectral lines remain prominent down to extremely low metallicities and are thus useful for providing stellar parameters via ionisation balance and as radial velocity diagnostics. However, the majority of studies that model these lines in late-type stars still rely on one dimensional (1D) hydrostatic model atmospheres and the assumption of local thermodynamic equilibrium (LTE). We present 3D non-LTE radiative transfer calculations of the CaT and HK lines in an extended grid of 3D model atmospheres of metal-poor FGK-type. We investigate the impact of 3D non-LTE effects on abundances, line bisectors and radial velocities. We used a subset of 3D model atmospheres from the recently published STAGGER-grid to synthesize spectra in 3D (non-)LTE. For comparison, similar calculations were performed in 1D (non-)LTE using models from the MARCS grid. Abundance corrections for the CaT lines relative to 1D LTE range from +0.1 to -1.0 dex, with more severe corrections for strong lines in giants. With fixed line strength, the abundance corrections become more negative with increasing effective temperature and decreasing surface gravity. Radial velocity corrections relative to 1D LTE based on cross-correlation of the whole line profile range from -0.2 km/s to +1.5 km/s, with more severe corrections where the CaT lines are strongest. The corrections are even more severe if the line core alone is used to infer the radial velocity. The line strengths and shapes, and consequently the abundance and radial velocity corrections, are strongly affected by the chosen radiative transfer assumption, 1/3D (non)-LTE. We release grids of theoretical spectra that can be used to improve the accuracy of stellar spectroscopic analyses based on the Ca II triplet lines.

The Laser Interferometer Space Antenna (LISA) will observe gravitational waves in the millihertz frequency band, detecting signals from a vast number of astrophysical sources embedded in instrumental noise. Extracting individual signals from these overlapping contributions is a fundamental challenge in LISA data analysis and is traditionally addressed using computationally expensive stochastic Bayesian techniques. In this work, we present a deep learning-based framework for blind source separation in LISA data, employing an encoder-decoder architecture commonly used in digital audio processing to isolate individual signals within complex mixtures. Our approach enables signals from massive black-hole binaries, Galactic binaries, and instrumental glitches to be disentangled directly in a single step, circumventing the need for sequential source identification and subtraction. By learning clustered latent space representations, the framework provides a scalable alternative to conventional methods, with applications in both low-latency event detection and full-scale global-fit analyses. As a proof of concept, we assess the model's performance using simulated LISA data in a controlled setting with a limited number of overlapping sources. The results highlight deep source separation as a promising tool for LISA, paving the way for future extensions to more complex datasets.

This article focuses on NGC7538 IRS1, one of the most luminous and studied HC HII regions in the northern hemisphere. Our aim is to identify the young stellar objects (YSOs) embedded within the ionized gas and study their kinematic structures. This work expands on a recent survey called "Protostellar Outflows at the EarliesT Stages" (POETS), which has been devoted to studying young outflow emission on scales of 10-100 au near luminous YSOs, before they start photoionizing the surrounding medium. We carried out multi-epoch Very Long Baseline Array observations of the 22 GHz water masers toward NGC7538 IRS1 to measure the maser 3D velocities, which, following POETS' findings, are reliable tracers of the protostellar winds. Recently, we reobserved the water masers in NGC7538 IRS1 with sensitive global very long baseline interferometry (VLBI) observations to map weaker maser emission. Our study confirms the presence of two embedded YSOs, IRS1a and IRS1b, at the center of the two linear distributions of 6.7 GHz methanol masers observed in the southern and northern cores of the HC HII region, which have been previously interpreted in terms of edge-on rotating disks. The water masers trace an extended (~200 au) stationary shock front adjacent to the inner portion of the disk around IRS1a. This shock front corresponds to the edge of the southern tip of the ionized core and might be produced by the interaction of the disk wind ejected from IRS1a with the infalling envelope. The water masers closer to IRS1b follow the same LSR velocity (Vlsr) pattern of the 6.7~GHz masers rotating in the disk, but the direction and amplitude of the water maser proper motions are inconsistent with rotation. We propose that these water masers are tracing a photo-evaporated disk wind, where the maser Vlsr traces mainly the disk rotation and the proper motions the poloidal velocity of the wind.

We use archival JWST/NIRCam images in the F115W, F150W, and F200W filters to measure the Tip of the Red Giant Branch (TRGB) magnitudes across the disk of the late-type spiral galaxy NGC 628. In this exploratory study, we demonstrate how the metallicity-dependence of TRGB magnitudes in the near-infrared (NIR) filters can be exploited by making use of the theoretical isochrones to determine metallicities of the fossil 10 Gyr old population over kiloparsec scales without being affected by the age-metallicity-reddening degeneracy. We obtain a smooth metallicity gradient that decreases from $Z$=0.003 in the central regions to $Z$=0.002 in the external parts, with a typical error on $Z$ of 0.0002. The extinction variation across the disk caused by the diffuse interstellar dust is spiky with a median value of $A_V$=0.12 mag. We propose that the large bubbles in the disks of galaxies offer dust-free lines of sight for measuring the TRGB magnitudes, and hence the distance to galaxies, to an accuracy that is as good as that of the halo populations. Using the Phantom Void, we obtain a TRGB distance modulus of 29.81$\pm0.05(\rm stat)\pm0.06(\rm sys)$ mag for NGC 628, which agrees well with the most recent PNLF measurement of 29.89$^{+0.06}_{-0.09}$ for this galaxy.

We present Transit Timing Variations (TTVs) of HAT-P-12b, a low-density sub-Saturn mass planet orbiting a metal-poor K4 dwarf star. Using 14 years of observational data (2009-2022), our study incorporates 7 new ground-based photometric transit observations, three sectors of Transiting Exoplanet Survey Satellite (TESS) data, and 23 previously published light curves. A total of 46 light curves were analyzed using various analytical models, such as linear, orbital decay, apsidal precession, and sinusoidal models to investigate the presence of additional planets. The stellar tidal quality factor ($Q_\star' \sim$ 28.4) is lower than the theoretical predictions, making the orbital decay model an unlikely explanation. The apsidal precession model with a $\chi_r^2$ of 4.2 revealed a slight orbital eccentricity (e = 0.0013) and a precession rate of 0.0045 rad/epoch. Frequency analysis using the Generalized Lomb-Scargle (GLS) periodogram identified a significant periodic signal at 0.00415 cycles/day (FAP = 5.1$\times$10$^{-6}$ %), suggesting the influence of an additional planetary companion. The sinusoidal model provides the lowest reduced chi-squared value ($\chi_r^2$) of 3.2. Sinusoidal fitting of the timing residuals estimated this companion to have a mass of approximately 0.02 $M_J$ , assuming it is in a 2:1 Mean-Motion Resonance (MMR) with HAT-P-12b. Additionally, the Applegate mechanism, with an amplitude much smaller than the observed TTV amplitude of 156 s, confirms that stellar activity is not responsible for the observed variations.

Aims. In the low-collisional, partially ionized plasma (PIP) of solar prominences, uncharged emitters might show different signatures of magnetic line broadening than charged emitters. We investigate if the widths of weak metall emissions in prominences exceed the thermal line broadening by a different amount for charged and for uncharged emitters. Methods. We simultaneously observe five optically thin, weak metall lines in the brightness center of a quiescent prominence and compare their observed widths with the thermal broadening. Results. The inferred non-thermal broadening of the metall lines does not indicate systematic differences between the uncharged Mg b2 and Na D1 and the charged Fe II emitters, only Sr II is broader. Conclusions. The additional line broadening of charged emitters is reasonably attributed to magnetic forces. That of uncharged emitters can then come from their temporary state as ion before recombination. Magnetically induced velocities will retain some time after recombination. Modelling partially ionized plasmas then requires consideration of a memory of previous ionization states.

We update constraints on a simple model of self-interacting neutrinos involving a heavy scalar mediator with universal flavor coupling. According to past literature, such a model is allowed by Cosmic Microwave Background (CMB) data, with some CMB and large-scale structure data even favoring a strongly-interacting neutrino (SI$\nu$) scenario over $\Lambda$CDM. In this work, we re-evaluate the constraints on this model in light of the new Planck NPIPE data, DESI BAO data, and the Effective Field Theory of Large Scale Structures (EFTofLSS) applied to BOSS data. We find that Planck NPIPE are more permissive to the SI$\nu$ scenario and that DESI data favor the SI$\nu$ over $\Lambda$CDM. However, when considering EFTofBOSS data, this mode is no longer preferred. Therefore, new DESI data analyzed under the EFTofLSS are particularly awaited to shed light on this disagreement.

Millisecond pulsars (MSPs) are prolific GeV {\gamma}-ray emitters, and nearly 80% of Fermi-LAT MSPs reside in compact binaries. We demonstrate that the companions in these compact MSPs binaries are also 511 keV annihilation line emitters using MEGAlib simulations (a high energy radiation transport software built with Geant4) to compute the particle showers and resulting backsplash emission from the pulsar irradiation. The 511 keV signal exhibits strong flux modulation and red/blueshifts associated with a binary orbit, enabling powerful coherent searches. Measuring the 511 keV emission would enable direct {\gamma}-ray characterization of unusual pulsar exoplanets and companions, and allow one to identify the unambiguous presence of active pulsars whose beams do not intercept Earth. Intriguingly, the 511 keV flux is brightest for ultra-compact systems against which pulsar surveys are systematically biased. These ultra-compact systems are also possibly prime LISA galactic sources. This necessitates future joint LISA-MeV {\gamma}-ray techniques to characterize MSP binaries. These MSP binaries may also contribute to the puzzling source of the excess 511 keV photons near the galactic bulge and center.

The Dark Matter Particle Explorer (DAMPE) is a space-based Cosmic-Ray (CR) observatory with the aim, among others, to study Cosmic-Ray Electrons (CREs) up to 10 TeV. Due to the low CRE rate at multi-TeV energies, we aim to increasing the acceptance by selecting events outside the fiducial volume. The complex topology of non-fiducial events requires the development of a novel energy reconstruction method. We propose the usage of Convolutional Neural Networks for a regression task to recover an accurate estimation of the initial energy.

Type II Cepheids (T2Ceps), alongside RR Lyrae stars, serve as important distance indicators for old population II stars due to their period-luminosity (PL) relations. However, studies of these relations in the Sloan photometric system are rather limited in the literature. Our goal is to calibrate PL relations (and their counterparts in Wesenheit magnitudes) in the Sloan-Pan-STARSS gP1rP1iP1 bands for Galactic T2Ceps located in the vicinity of the Sun. We collected data for 16 T2Ceps of the BLHer type and 17 of the WVir type using 40 cm telescopes of the Las Cumbres Observatory Global Telescope Network. Geometric parallaxes were adopted from Gaia Data Release 3. We have calibrated PL and period-Wesenheit relations for Milky Way BLHer and WVir stars in the solar neighborhood, as well as for a combined sample of both types. The relationships derived here will allow to determine the distances to T2Ceps that will be discovered by the Legacy Survey of Space and Time survey and, in turn, to probe the extended halo of the Milky Way, as well as the halos of nearby galaxies. To the best of our knowledge, the relations derived in this study are the first for Milky Way T2Ceps in the Sloan bands.

Context. The nearby middle-aged gamma-ray pulsar J1741-2054 and its pulsar wind nebula (PWN) have been studied in X-rays, and its bow-shock nebula (BSN) has been investigated in the Balmer lines, but they have never been observed in far ultraviolet (FUV). Aims. To further study the thermal and magnetospheric emission from PSR J1741-2054 and the BSN properties, we observed them in the FUV range with the Hubble Space Telescope (HST). Methods. We imaged the target in two FUV filters of the HST's ACS/SBC detector. We also re-analyzed previous optical observations of the pulsar and its BSN. We fit the pulsar's FUV-optical spectrum separately and together with its X-ray spectrum. Results. We found that the pulsar's FUV-optical spectrum consists of a thermal and nonthermal components. A joint fit of the FUV-optical and X-ray spectra with combinations of a nonthermal and thermal components showed a hard optical nonthermal spectrum with a photon index $\Gamma_{opt} \approx 1.0-1.2$ and a softer X-ray component, $\Gamma_X \approx 2.6-2.7$. The thermal emission is dominated by the cold component with the temperature $kT_{cold}\approx 40-50$ eV and emitting sphere radius $R_{cold}\approx 8-15$ km, at $d=270$ pc. An additional hot thermal component, with $kT_{hot}\sim 80$ eV and $R_{hot}\sim 1$ km, is also possible. Such a spectrum resembles the spectra of other middle-aged pulsars, but it shows a harder (softer) optical (X-ray) nonthermal spectrum. We detected the FUV BSN, the first one associated with a middle-aged pulsar. Its closed-shell morphology is similar to the H$\alpha$ BSN morphology, while its FUV flux, $\sim10^{-13}$ erg cm$^{-2}$ s$^{-1}$, is a factor of $\sim 4$ higher than the H$\alpha$ flux. This FUV BSN has a higher surface brightness than the two previously known ones.

We investigate a non-parametric Bayesian method for reconstructing the primordial power spectrum (PPS) of scalar perturbations using temperature and polarisation data from the {\em Planck}, ACT, and SPT CMB experiments. This reconstruction method is based on linear splines for the PPS between nodes in $k$-space whose amplitudes and positions are allowed to vary. All three data sets consistently show no significant deviations from a power-law form in the range $0.005 \lesssim k\,\mathrm{Mpc} \lesssim 0.16$ independent of the number of knots adopted to perform the reconstruction. The addition of high-resolution CMB measurements from ACT and SPT slightly improves the range of scales of the scalar PPS which are well constrained around a power law up to $k \simeq 0.25\,\mathrm{Mpc}^{-1}$ and $k \simeq 0.2\,\mathrm{Mpc}^{-1}$, respectively. At large scales, a potential oscillatory feature in the primordial power spectrum appears when we consider six or more nodes. We test the robustness of the methodology and our results by varying the detailed number of knots from $N=2$ to $N=10$. We have used the reconstructed scalar PPS to derive several quantities related to inflationary related to inflationary dynamics, such as the effective scalar spectral index, which describes the dependence of the PPS on the scales and parameters associated with the effective field theory of inflation, to provide information on possible departures from the standard single-field canonical case. Finally, we investigate whether the excess of smoothing in the region of the region of the acoustic peaks of the CMB anisotropy temperature power spectrum in the \textit{Planck} PR3 data is degenerate with our reconstructions of the PPS, but find no significant correlation between them.

Recent wide-field galaxy surveys have led to an explosion in numbers of galaxy-scale strong gravitational lens candidates. However, the vast majority feature massive luminous red galaxies as the main deflectors, with late-type galaxies being vastly under-represented. This work presents a dedicated search for lensing by edge-on late-type galaxies in the Ultraviolet Near Infrared Optical Northern Survey (UNIONS). The search covers $3600$ deg$^2$ of $r$-band observations taken from the Canada-France-Hawaii Telescope. We consider all sources with magnitudes in the range $17 < r < 20.5$, without any colour preselection, yielding a parent sample of seven million sources. We characterise our parent sample via the visual inspection of $120\,000$ sources selected at random. From it, we estimate, with a 68\% confidence interval, that 1 in every $30\,000$ sources is an edge-on lens candidate, with at least eight high-quality candidates in the parent sample. This corresponds to 1 candidate per $17\,000$ edge-on late-type galaxies. Our search relies on a convolutional neural network (CNN) to select a reduced sample of candidates, followed by a visual inspection to curate the final sample. The CNN is trained from scratch using simulated $r$-band observations of edge-on lenses, and real observations of non-lenses. We find 61 good edge-on lens candidates using the CNN. Moreover, combining the CNN candidates with those found serendipitously, and those identified while characterising the parent sample, we discovered 4 grade A, 20 grade B, and 58 grade C edge-on lens candidates; effectively doubling the known sample of these systems. We also discovered 16 grade A, 16 grade B, and 18 grade C lens candidates of other types. Finally, based on the characterisation of the parent sample, we estimate that our search found around 60\% of the bright grade A and B edge-on lens candidates within the parent sample.

Particle dark matter scattering on electrons in the Sun may gravitationally capture and self-annihilate inside it to neutrinos and anti-neutrinos, or other final states that in turn decay to them. Using up-to-date measurements by Super-Kamiokande of the fluxes of atmospheric electron-type and muon-type neutrinos, we set the most stringent limits on the electron scattering cross sections of dark matter down to about $10^{-40}-10^{-39}$ cm$^2$ over a mass range of 4$-$200 GeV. These outdo direct searches for dark matter-electron scattering and previously set limits at IceCube. We also derive corresponding reaches at Hyper-K, and show that atmospheric neutrino observations restricted to the direction of the Sun can improve sensitivities.

We search for the existence of ultralight axions coupling to electrons and photons using data from the NuSTAR telescope directed toward the galaxies M82, M87, and M31. We focus on electron bremsstrahlung and Compton scattering for axion production in stars, summing over the stellar populations found in the target galaxies when computing the axion luminosity. We then compute the hard X-ray signal that arises from the conversion of these axions to photons in each galaxy's magnetic fields, inferred from analog galaxies in cosmological magnetohydrodynamic simulations. Analyzing NuSTAR data toward these galaxies between roughly 20 to 70 keV, we find no evidence for axions and set leading constraints on the combined axion-electron and axion-photon coupling at the level of $|g_{aee} \times g_{a \gamma \gamma}| \lesssim 8.3 \times 10^{-27}$ GeV$^{-1}$ for $m_a \lesssim 10^{-10}$ eV at 95% confidence, with M82 providing the most stringent constraints.

We present a new technique for sub-GeV dark matter (DM) searches and a new use of neutrino observatories. DM-electron scattering can excite or ionize target molecules in the observatory, which then produce light that can be detected by its photomultiplier tubes (PMTs). While individual DM scatterings are undetectable, the aggregate rate from many independent scatterings can be isolated from the total PMT dark rate using the expected DM annual modulation. We showcase this technique with the example of JUNO, a 20,000 ton scintillator detector, showing that its sensitivity in some mass ranges exceeds all other techniques and reaches key particle-theory targets.

Supernova cooling has long been used to constrain physics beyond the Standard Model, typically involving new mediators or dark matter (DM) particles that couple to nucleons or electrons. In this work, we show that the large density of neutrinos inside the neutrinosphere of supernovae also makes them powerful laboratories to study nonstandard neutrino interactions with a {\it neutrinophilic} dark sector, i.e.~DM and mediator particles interacting primarily with neutrinos. In this case, we find that the existing constraints are rather weak, and for a wide range of currently unconstrained parameter space, neutrino annihilation within a supernova could copiously produce such neutrinophilic DM at a large enough rate to cause noticeable anomalous cooling. From the non-observation of such anomalous cooling in SN1987A, we thus set new constraints on neutrino-DM interactions, which provide up to four orders of magnitude improvement over the existing constraints for DM masses below ${\cal O}$(100 MeV).

Current template-based gravitational-wave searches for compact binary mergers neglect the general relativistic phenomenon of spin-induced orbital precession. Owing to their asymmetric masses, gravitational-waves from neutron star-black hole (NSBH) binaries are prime candidates for displaying strong imprints of spin-precession. As a result, current searches may be missing a significant fraction of the astrophysical population, and the detected NSBH population may be significantly suppressed or biased. Here we report the most sensitive search for NSBH binaries to date by including spin-precession for the first time. We analyze data from the entirety of the third LIGO-Virgo-KAGRA gravitational-wave observing run and show that when accounting for spin-precession, our search is up to 100% more sensitive than the search techniques currently adopted by the LIGO-Virgo-KAGRA collaboration (for systems with strong precessional effects). This allows us to more tightly constrain the rate of NSBH mergers in the local Universe. Firstly, we focus on a precessing subpopulation of NSBH mergers; the lack of observed candidates allows us to place an upper limit on the merger rate of $R_{90} = 79\, \mathrm{Gpc}^{-3}\mathrm{yr}^{-1}$ with 90% confidence. Secondly, we tighten the overall rate of NSBH mergers; we show that if there is no preferred direction of component spin, the rate of NSBH mergers is on average 16% smaller than previously believed. Finally, we report four new subthreshold NSBH candidates, all with strong imprints of spin precession, but note that these are most likely to be of terrestrial origin.

We derive the first analytical formula for the density of "Dark Matter" (DM) at all length scales, thus also for the rotation curves of stars in galaxies, for the baryonic Tully-Fisher relation and for planetary systems, from Einstein's equations (EE) and classical approximations, in agreement with observations. DM is defined in Part I as the energy of the coherent gravitational field of the universe, represented by the additional equivalent ordinary matter (OM), needed at all length scales, to explain classically, with inclusion of the OM, the observed coherent gravitational field. Our derivation uses both EE and the Newtonian approximation of EE in Part I, to describe semi-classically in Part II the advection of DM, created at the level of the universe, into galaxies and clusters thereof. This advection happens proportional with their own classically generated gravitational field g, due to self-interaction of the gravitational field. It is based on the universal formula rD=lgg'g' for the density rD of DM advected into medium and lower scale structures of the observable universe, where l is a universal constant fixed by the Tully-Fisher relations. Here g' is the gravitational field of the universe; g' is in main part its own source, as implied in Part I from EE. We start from a simple electromagnetic analogy that helps to make the paper generally accessible. This paper allows for the first time the exact calculation of DM in galactic halos and at all levels in the universe, based on EE and Newtonian approximations, in agreement with observations.

In JCAP 11 (2024) 051, we discussed how different regimes (flavoured) of leptogenesis can be probed through a ``tomographic'' approach using primordial gravitational waves. By examining the theory's parameter space, we identified regions where right-handed neutrino mass-dependent non-standard cosmological expansion leaves characteristic imprints on propagating gravitational waves. Our analysis focused on inflationary blue-tilted gravitational waves, modeled by a power-law tensor power spectrum with a constant spectral index. The resulting double-peak spectrum -- where peak and dip frequencies are sensitive to leptogenesis parameters -- provided marked signatures of different leptogenesis regimes. In this follow-up article, we conduct a statistical analysis of two-flavour leptogenesis signals, particularly those producing a peak (more generally, a broken power-law signal) within the LISA frequency band. Using a Fisher matrix analysis, we delineate the regions of parameter space that LISA can probe with minimal uncertainty, accounting for galactic and extragalactic foregrounds along with LISA's instrumental noise.

Quasi-normal modes (QNMs) and greybody factors are some of the most characteristic features of the dynamics of black holes (BHs) and represent the basis for a number of fundamental physics tests with gravitational wave observations. It is therefore important to understand the properties of these quantities, naturally introduced within BH perturbation theory, in particular the stability properties under modifications of the BH potential. Instabilities in the QNMs have been recently shown to appear in the BH pseudospectrum under certain circumstances. In this work, we give a novel point of view based on the existence of some recently discovered hidden symmetries in BH dynamics and the associated infinite series of conserved quantities, the Korteweg-de Vries (KdV) integrals. We provide different motivations to use the KdV integrals as indicators of some crucial BH spectral properties. In particular, by studying them in different scenarios described by modified BH barriers, we find strong evidence that the KdV conserved quantities represent a useful tool to look for instabilities in the BH spectrum of QNMs and in their greybody factors.

The double-pass interferometer scheme was proposed in Ref.\,[Light Sci. Appl. {\bf 7}, 11 (2018)] as the method of implementation of the quantum speed meter concept in future laser gravitational-wave (GW) detectors. Later it was shown in Ref.\,[Phys. Rev. D {\bf 110}, 062006 (2024)] that it allows to implement the new type of the optical spring that does not require detuning of the interferometer. Here we show that both these regimes can coexist, combining the speed meter type broadband sensitivity gain with the additional lows-frequency minimum in the quantum noise originated from the optical spring. We show that the location of this minimum can be varied without affecting the core optics of the interferometer, allowing to tune the quantum noise shape in real time to follow the ``chirp'' GW signals.

It is a common lore that in the thermal leptogenesis in the type-1 seesaw scenario with the conventional hierarchy of heavy right-handed neutrinos (RHNs), the CP violating, out-of-equilibrium decay of the lightest RHN ($N_1$) is the only relevant source of $B-L$ asymmetry. Any asymmetry produced by the heavier RHNs ($N_2$ and $N_3$) gets washed out by the lepton number violating processes mediated by $N_1$. In this paper, we examine this assumption comprehensively, considering decay and inverse decay processes as well as the inclusion of scatterings. We find that the above said assumption is true only if all the RHNs ($N_1, N_2$ and $N_3$) are in strong washout regime. However, we saw that, to satisfy the neutrino masses and mixing given by the low energy neutrino oscillation data, at most one of the RHNs can be in the weak washout regime. This leads to, if $N_1$ is in the weak washout regime, then the washout parameters of $N_2$ and $N_3$ can be chosen in such a way that the impact of $N_2$ and $N_3$ on the final $B-L$ asymmetry is relatively small. On the other hand, if $N_2$ or $N_3$ is in weak washout regime, then the asymmetry produced by them can affect the final $B-L$ asymmetry even if $N_1$ is in the strong washout regime, which we call the memory effect. We delineated the parameter space where the memory effect is significant.