Papers for Thursday, Mar 19 2026

Interstellar comets arrive with key ingredients for deep-space platforms already in place: volatile inventories convertible to propellant, natural rotation providing continuous attitude variation, and hyperbolic trajectories that carry them through the inner Solar System and back out to interstellar space. Rather than constructing spacecraft from scratch, we ask what \emph{minimal modification} is required to steer such a body along a controlled trajectory. The answer is surprisingly modest. By relaxing full six-degree-of-freedom control to forward-cone steering -- sufficient for practical navigation -- we show that \emph{four thrusters suffice}: one primary jet and three secondary jets at $120^\circ$ intervals. The secondary jets synthesize continuous in-plane steering, while the primary jet provides low-bandwidth attitude shaping: as the body rotates, the primary-jet torque direction sweeps predictably over a cycle, enabling out-of-plane steering via phase-scheduled firing. We formalize reachability under bounded-curvature constraints, characterize the rotation-mediated steering envelope, discuss enabling requirements including non-solar power at large heliocentric distances, and identify operational regimes and observable signatures implied by active trajectory control. The setting of a nutating axis is briefly considered and conjectured to preserve core results. The findings contribute to the broader effort of understanding the dynamics and control of small-body missions and offer a reference architecture relevant to long-horizon deep-space exploration and to potential planetary-defense concepts.

Interstellar objects (ISOs) motivate a coupled mission-design and inference question relevant to spacecraft dynamics and control in extreme environments: if volatile-rich, rotating comet-like bodies were used for sustained deep-space navigation by exploiting pre-existing hyperbolic motion and in-situ propellant, what stability requirements arise under non-gravitational forcing, and what astrometric signatures might distinguish active stabilization from uncontrolled natural dynamics? We develop a stability-theoretic framework for trajectory tracking with jet-actuated correction, and show that high-speed transit geometry -- including debris-belt avoidance and encounter phasing -- tightly constrains feasible trajectories, making long-horizon tracking stability mission-critical. We model tracking residuals as the balance of disturbances and corrective action, and derive stability conditions across four levels: disturbance-energy stability, outer-loop contraction, actuator-memory stability, and rotation-mediated (Floquet) stability. The analysis implies residual diagnostics that can motivate empirical tests: under comparable forcing, effective stabilization is expected to strengthen short-horizon error correction, reduce event-conditioned persistence and variance clustering, regularize standardized innovations, and yield bounded post-shock recovery. More broadly, the framework provides a reference for deep-space guidance and control under nonlinear, multi-field disturbances and for planetary-defense concepts involving attitude shaping or impulsive kinetic impact.

Galactic haloes host a complex, multiphase circumgalactic medium (CGM), and at high redshift are fed by cold, filamentary inflows. In contrast, mature galaxy clusters are dominated by a hot, enriched, X-ray emitting intracluster medium (ICM), with cold gas largely confined to member galaxies. However, the transition between these regimes remains poorly constrained. We present a cosmological zoom-in simulation of a massive cluster progenitor evolved to $z=2.7$, with enhanced CGM resolution to better trace the accretion, mergers and feedback events that precede the birth of the ICM. We connect this evolution to mock MgII and OVII absorption, tracing low and high ionisation gas phases. We also study Lyman-$\alpha$ (Ly$\alpha$) and Balmer-$\alpha$ (H$\alpha$) haloes in emission, using radiative transfer in post-processing. Between $z\sim4.4$ and $2.7$, a major merger and AGN feedback drive an inside-out transformation, redistributing gas to larger radii and flattening density, temperature and metallicity profiles. Intermediate column MgII absorbers are rapidly destroyed, leaving a clumpier cold gas distribution associated with satellites, while gas is ionised beyond OVII as the inner halo enters the X-ray regime. An extended Ly$\alpha$ halo remains detectable even without AGN photoionisation, and evolves from filamentary to more spherical as inflowing gas is disrupted. Our fiducial model underpredicts observed central Ly$\alpha$ emission - we likely require more efficient Ly$\alpha$ production in the nuclear region, either through more effective escape of stellar Ly$\alpha$ photons or through enhanced conversion of AGN-powered ionisation into Ly$\alpha$ emission. H$\alpha$ haloes are dimmer and smaller than Ly$\alpha$, but with JWST may provide a complementary probe of the evolving CGM at this critical epoch.

Measuring galaxy rotation curves is critical for inferring the properties of dark-matter haloes in the Lambda Cold Dark Matter ($\Lambda$CDM) paradigm. We present HI rotation curves and mass models for 20 galaxies from the MIGHTEE survey. Using extended HI kinematics, we construct resolved mass models that include stellar, gaseous, and dark-matter components. Stellar masses are derived using 3.6 $\mu$m imaging under fixed mass-to-light ratio ($\Upsilon_{*} = M/L$) assumptions and are complemented, for the first time for a HI-selected sample, by spatially resolved $M/L$, obtained from multi-wavelength SED fitting. We examine the ratio of baryonic to observed rotation velocity ($V_{\rm bar}/V_{\rm obs}$) at the characteristic radius $R_{2.2}$. Adopting a fixed $\Upsilon_\star = 0.5\,M_\odot/L_\odot$ yields a clear dependence of $V_{2.2}/V_{\rm obs}$ on galaxy luminosity, while adopting $\Upsilon_\star = 0.2\,M_\odot/L_\odot$ substantially weakens this trend. In contrast, the resolved $M/L$ analysis preserves the luminosity dependence while modifying the stellar contribution on a galaxy-by-galaxy basis, providing a more accurate representation of the underlying relation. We model the dark-matter haloes using Navarro-Frenk-White profiles and find that the different assumptions for a fixed a $M/L$ systematically shift galaxies relative to the theoretical stellar-to-halo mass and baryonic-to-halo mass relations, while the spatially varying $M/L$ yields the closest agreement with theoretical benchmarks within $\Lambda$CDM. We therefore demonstrate that future investigations of the dark matter properties of galaxies using rotation curves need to account for varying $M/L$ across individual galaxy profiles and between galaxies in order to obtain accurate measurements of the dark matter, and therefore test $\Lambda$CDM.

Ram-pressure stripping is a key driver of galaxy morphological transformation in clusters, contributing to the formation of quenched, especially dwarf, populations. Ram-pressure compression can also induce a starburst prior to quenching and build up significant stellar mass in an initially gas-rich galaxy. The detailed physics of these processes remains poorly understood, especially in the low-mass regime. Here we demonstrate that the key factor for a ram-pressure induced starburst in a low-mass galaxy is its angular momentum within a host cluster. In this study, we select a sample of 41 post-starburst galaxies (PSGs) in the Coma cluster using the DESI EDR spectroscopic data, extending to low luminosities ($M_g < -14$). This sample is at least 90% complete down to $M_g \approx -14.8$, which enabled us a systematic analysis of their properties. For each galaxy, we use projected cluster-centric distances and line-of-sight velocities to constrain the normalized orbital angular momentum and a 3D radial coordinate to the cluster center, assuming zero orbital energy. The resulting probability distributions show that while star-forming galaxies are split into two populations favoring intermediate and high angular momentum, almost all PSGs prefer high angular momentum. Our analysis statistically demonstrates that ram-pressure-induced starbursts are more efficient on tangential orbits, where gas stripping proceeds slowly enough to allow substantial star formation before gas removal.

Recent observations have shown that sufficiently slow rotation disrupts the organization of large-scale magnetic field in older main-sequence stars, leading to weakened magnetic braking (WMB) and a collapse in the efficiency of the global stellar dynamo. Recent simulations predict a shift from solar-like to anti-solar differential rotation (DR) at slower rotation rates, which typically do not occur on the main-sequence due to WMB. However, physical expansion on the subgiant branch can eventually slow the stellar rotation beyond this threshold, yielding a non-cycling large-scale field that revives magnetic braking. We combine asteroseismology from the Transiting Exoplanet Survey Satellite (TESS) with spectropolarimetry from the Large Binocular Telescope (LBT) to test these predictions in the old metal-rich subgiant 31 Aql. The LBT observations reveal a strong large-scale magnetic field in this star, and archival measurements of its chromospheric emission over 50 years confirm that it is non-cycling, as predicted. The star exhibits a variety of rotation periods during different observing seasons, consistent with DR but with no means of distinguishing between solar-like and anti-solar patterns. We incorporate the TESS observations to estimate the current wind braking torque of 31 Aql, demonstrating that it supports revived magnetic braking in this old subgiant. We also use rotational evolution modeling to place a preliminary constraint on the stellar Rossby number for the transition to anti-solar DR. Future refinements in both asteroseismic observations and rotational modeling may yield improvements to this initial analysis.

Non-linear interactions during inflation generate non-Gaussianities in the distribution of primordial curvature. In many theories, the physics is scale-invariant, such that the induced three-point function depends solely on a dimensionless shape function $S(x,y)\sim k^6B_\zeta(kx,ky,k)$. To confront such models with observations, one typically builds specialized estimators for each shape, then applies them to cosmic microwave background datasets at significant computational expense. In this Letter, we take a different approach, directly reconstructing $S(x,y)$ from observations using an efficient logarithmically-binned estimator in primordial-space (motivated by the modal program). Applying this to temperature and polarization maps from Planck, we obtain high-resolution shape measurements across the full $(x,y)$-plane, including squeezed limits. Our approach is close-to-optimal, highly interpretable, and preserves the information content on (optimally-analyzed) standard templates within $\approx 10\%$; moreover, we can use it to assess the scale-dependence of our constraints, finding that Planck is sensitive to $\approx 6$ $e$-folds of non-Gaussian evolution with a peak sensitivity around $0.1h\,\mathrm{Mpc}^{-1}$. Since we work directly in shape-space, data and theory can be compared in milliseconds. As an example, we perform a search for massive particle exchange using a suite of over $20\,000$ theoretical templates computed with exact bootstrap methods (for the first time) across a wide range of masses, spins, and sound-speeds; the spin-two analysis yields a maximum significance of $2.6\sigma$. Our approach can be used to probe a wide range of scale-invariant models in orders-of-magnitude less time than with direct estimators, allowing the inflationary paradigm to be explored in new ways.

The recent gravitational-wave (GW) alert from a compact object merger involving at least one subsolar mass (SSM) object has prompted questions about their origins. S251112cm is reported by LIGO/Virgo with a false alarm rate of 1 per 6.2 years, nearby luminosity distance $93 \pm 27$ Mpc, probability of containing a SSM object of 100%, and probability of containing a $1-3~M_\odot$ object of just 8%. Such a system likely did not involve the supersolar neutron stars or black holes invoked to explain kilonovae. One must then also invoke hitherto unobserved and speculative models to produce SSM mergers and the resultant electromagnetic (EM) counterparts. We introduce a framework which vets and scores candidate counterparts to SSM GW events to inform follow-up in search of any among the zoo of potential EM transients: kilonovae, kilonovae-within-supernovae, super-kilonovae, or AGN flares from binary black hole mergers. We use a suite of telescopes to perform tiling, galaxy-targeted observations, and photometric/spectroscopic follow-up of promising candidates. In near-real time, we ingest candidates reported by the community, including some of the first observations reported by the Vera C. Rubin Observatory. We vet and score a total of 248 candidates, including 67 from Rubin, but find no likely counterpart. We nonetheless highlight candidates which demonstrate the ability of our framework to distinguish between different transient types and describe strategies to maximize the chances of detecting a counterpart to the next SSM event. Our framework will be implemented in the forthcoming Multimessenger Tool for Rapid Object Vetting and Examination (TROVE).

We have recently suggested that Nunki=Sigma Sagittarii is the closest core collapse progenitor candidate to the Sun based on a VLTI/GRAVITY observation that unveiled it as a $6.5+6.3 M_{\odot}$ binary at a projected separation of 0.60 au. Here we combine this observation with three VLTI/PIONIER archival and one previous MAPPIT observation to solve for the orbit of \textit{Nunki}, finding $a=1.26\pm0.05 \text{ au}$ ($P=134.779\pm0.025 \text{ days}$) and thereby confirming it as a close binary. The low orbital inclination $i=19.7\pm1.9^{\circ}$ coupled with the high projected rotational velocity $v \sin i \simeq 160 \text{ km}\text{ s}^{-1}$ and the absence of a decretion disk are a strong hint for spin-orbit misalignment. The significant eccentricity $e=0.492\pm0.003$ will cause the system to undergo eccentric Roche lobe overflow once the primary expands to $R\simeq50 R_{\odot}$, so that a merger into a $M \gtrsim 10 M_{\odot}$ star is a possible outcome. Therefore, we conclude that \textit{Nunki} at a distance $d \approx 69 \text{ pc}$ can indeed be considered the closest core collapse progenitor candidate to the Sun as it is closer than \textit{Spica} and \textit{Bellatrix} both at $d \approx 77 \text{ pc}$. Furthermore, we also report on a VLTI/GRAVITY observation of \textit{Bellatrix} that shows that it does not have any close companion with a K band flux ratio higher than 1\%; in particular, it is not a close equal mass binary as previously suspected. Two archival spectra of \textit{Nunki} illustrate how equal-mass binaries with rapidly rotating components can easily hide to become virtually spectroscopically undetectable when the radial velocity separation is several times smaller than the individual line widths.

Ultrahigh-energy gamma rays ($E_{\gamma}>100 \, {\rm TeV}$) have been detected from a handful of astrophysical sources. Due to the Klein-Nishina suppression of inverse Compton scattering at such high energies, it has sometimes been argued that these sources must be accelerators of PeV-scale protons, making them the long-sought-after Galactic ''PeVatrons.'' Here, we challenge this conclusion, demonstrating that these sources can be straightforwardly explained by simple leptonic models. In this context, we consider the microquasar SS 433, the Galactic Center, and TeV halos, showing in each case that the observation of PeV-scale gamma rays from these sources does not indicate that they are accelerators of hadronic cosmic rays. We also note that the measured angular extension of SS 433 is in good agreement with the predictions of our model, favoring a leptonic origin for the gamma-ray emission from this source. A definitive identification of a PeVatron would require additional information, such as the combined observation of the pion bump and synchrotron peak, the spatial correlation of gamma-ray emission with gas, or the detection of neutrinos with $E_{\nu} \gtrsim 100 \, {\rm TeV}$.

Swift J1727.8$-$1613 is a newly discovered transient low-mass X-ray binary harbouring a stellar-mass ($\sim 10M_\odot$) black hole. We present state-resolved VLT/X-Shooter optical spectroscopy of its 2023 outburst, sampling the luminous hard-to-soft and late soft-to-hard transitions. During the onset of the brightest radio flare, He\,\textsc{ii} flux rises relative to adjacent epochs, with reduced peak-to-peak separation and full-width-half-maximum, consistent with enhanced irradiation shifting line emissivity to larger radii. We detect no contemporaneous change in the line base tracing the inner disc. The most dramatic change occurs at the onset of the dim-hard state, when strong, broad (higher-order) Balmer lines appear in absorption, and He\,\textsc{ii} remains in emission, but becomes highly asymmetric. While the hardening of the X-ray spectrum likely promotes the reappearance of an underlying disc photosphere, the kinematic alignment between the Balmer absorption ($v_w\sim-750\,\mathrm{km\,s^{-1}}$) and the suppressed blue peak of He\,\textsc{ii} suggests a unified origin in a massive, cool ($T\lesssim10^{4}\,\mathrm{K}$) accretion disc wind. Radiative transfer simulations demonstrate that such asymmetric He\,\textsc{ii} profiles are naturally produced in a rotating and accelerating outflow. Using the Sobolev approximation, we estimate the wind mass-loss rate to be $\dot{M}_w\gtrsim10^{-9}\,M_\odot\,\mathrm{yr^{-1}}$, comparable to the instantaneous accretion rate and a significant fraction of the secular mass-transfer rate from the donor. If persistent at quiescent-level X-ray luminosities, this outflow could strongly impact the system's secular evolution.

Mass transfer in stellar binaries has been well studied in most stellar mass ranges, with the notable exception of ultracool stars and substellar brown dwarfs. We report the discovery of ZTF J1239+8347 with the Zwicky Transient Facility (ZTF), a brown dwarf binary currently undergoing stable mass transfer with an orbital period of 57.41 minutes. Optical time-series photometry reveals an extremely high amplitude ($> 2$ magnitude peak-to-trough) variability at short wavelengths indicative of an orbiting hot spot slightly buried inside the atmosphere of the accretor. We use parallax measurements from \textit{Gaia} along with optical and near infrared spectra to infer an accretion temperature of $T_\mathrm{eff} = 8904 \pm 54$ K, an atmospheric temperature of the accretor of $T_\mathrm{atmo} \approx 1500$ K, and a slightly inflated accretor radius of $R_{\rm acc} = 1.20^{+0.15}_{-0.11} \, \RJup$. ZTF J1239+8347 is a direct impact accretor, typically only seen in double degenerate white dwarf binaries, which are approximately a million times denser than the components in ZTF J1239+8347. The existence of an accreting brown dwarf binary suggests that angular momentum loss can be strong enough to make ultracool binaries interact in a Hubble time. The observed faintness ($\sim 20$ mag) and relative proximity ($\approx 300$ pc) of ZTF J1239+8347 suggests that many similar systems are likely to be found by the upcoming Rubin Observatory Legacy Survey of Space and Time (LSST).

Substellar objects such as brown dwarfs and planets are generally expected to remain detached from their main-sequence host stars unless orbital decay or stellar expansion brings them into contact, leading to rapid engulfment and destruction. Such a fate is predicted for the Earth and other rocky planets in our solar system; however, in certain cases, theory also allows for stable long-lived mass transfer from a substellar object onto its main-sequence host, though such accretion has never been directly observed. Here we report the first direct observations of stable mass transfer from a substellar object onto a main-sequence star. In particular, we identify two binaries, ZTF J0440+2325 and ZTF J1444+4820, with orbital periods of just 87 and 67 minutes, respectively, in which a brown dwarf stably transfers mass onto an M dwarf companion. These systems demonstrate that the fate of some substellar objects is not rapid engulfment and destruction, but instead gradual consumption for potentially billions of years.

Several dozen binary ultracool and brown dwarf systems have been identified to date. These systems represent valuable probes of star and planet formation at the lowest mass scales. To date, the study of these ultracool binaries has been constrained to the non-interacting case. In this paper, we investigate the dynamics, stability, and evolution of mass transferring ultracool binaries using numerical simulations with accepted equations of state for brown dwarfs. We find that there exists a donor mass inversion, above which the donor dwarf is more massive than the accretor, but below which the accretor is more massive than the donor. Below the hydrogen burning limit, objects with mass ratios $q \sim 1$ are unstable, but slight deviations from this mass ratio are stable at the onset of mass transfer and remain stable throughout extended periods. We compute theoretical mass transfer rates using several angular momentum loss prescriptions and predict lifespans of $\sim 100$ Myrs. We predict that all mass transferring ultracool binaries are tidally locked and possess orbital periods ranging from just under $1$ hour to $3.5$ hours. We find that mass transfer proceeds via direct impact onto the accretor forming a UV or optically bright hotspot on the surface of the accretor.

Radio-loud active galactic nuclei (AGN) are among the most luminous objects in the Universe, emitting radiation from low-energy radio waves to high energy $\gamma$-rays. They are well known to exhibit flux variations at nearly all accessible wavelengths. However, their variability properties in the ultraviolet (UV) band remain relatively less explored compared to other wavebands. Here, we present the results of a systematic investigation of the UV flux and spectral variability characteristics of 24 radio-loud AGN spanning the redshift range 0.018 $\le$ $z$ $\le$ 2.218. The sample comprises 17 BL Lac objects, 6 flat spectrum radio quasars (FSRQs) and one radio-loud narrow line Seyfert 1 galaxy. We used observations obtained with the Ultra-Violet Imaging Telescope (UVIT) onboard AstroSat during its first ten years of operation, covering both the far-UV (FUV; 1300$-$1800 Å) and near-UV (NUV; 2000$-$3000 Å) bands. Of the 24 sources analysed, 18 showed significant UV variability on hour timescales. We found a bluer when brighter (BWB) spectral trend in two sources: the FSRQ CTA 102 and the BL Lac PKS 0447$-$439. The observed UV variability in our sample of radio-loud AGN, together with the BWB trend detected in these two sources, supports a scenario in which the hour timescale UV variations are driven by intrinsic processes within their relativistic jets.

The Laser Interferometer Space Antenna (LISA) will enable precision studies of Extreme and Intermediate Mass Ratio Inspirals (EMRIs/IMRIs), providing unique probes of astrophysical environments of galactic nuclei and strong-field gravity. Using a fully relativistic pipeline across primary masses $m_1 \in [5\times10^4, 10^7]\,M_\odot$ and secondary masses $m_2 \in [1, 10^4]\,M_\odot$, we map instrumental performance directly to detection horizons and parameter measurement precision. EMRIs with $m_1 = 10^7\,M_\odot$ and $m_2 \sim 1\,M_\odot$ are the most sensitive to instrument degradation, with redshift horizons at $z \sim 0.01$, while IMRIs are the least sensitive to degradation and reach redshifts $z \sim 1-3$. All prograde systems considered achieve sub-percent spin precision within three months of observation. The full 4.5-year mission increases the horizon of systems with $m_1 = 10^7\,M_\odot$ and $m_2 \sim 1\,M_\odot$ by a factor of $\sim 4$ and improves sky localization by one to two orders of magnitude reaching $ < 10\,\mathrm{deg}^2$. IMRI detection is robust against degradation, but their parameter estimation is more vulnerable due to fewer cycles in band. With the full baseline, EMRI observations constrain scalar dipole emission and Kerr quadrupole deviations below ground-based bounds by one to two orders of magnitude. We release the accompanying software and an interactive website to enable the community to rapidly quantify the scientific potential of EMRIs and IMRIs.

This work discusses the broadband X-ray spectral analysis of 11 candidate heavily-obscured active galactic nuclei (AGN) selected based on their infrared and X-ray properties by a recently published machine learning algorithm. This paper is part of a larger work to identify and characterize all AGN in the local universe (z < 0.1) with the largest line-of-sight (los) column densities (NH), the so-called Compton-thick (CT-, NH,los >= 1024 cm-2) AGN. We modeled the X-ray spectra using two physically- motivated models, UXClumpy and RXTorusD. Of the 11 AGN in our sample, we found three to be obscured with 22.7 < LogNH,los <= 23.0, five have 23.0 < LogNH,los <= 23.25, and three have 23.4 < LogNH,los <= 23.9, according to UXClumpy. Meanwhile, according to RXTorusD, we found three AGN to be obscured with 22.7 < LogNH,los <= 23.0, four with 23.0 < LogNH,los <= 23.4, and four with 23.85 < LogNH,los <= 23.96. Additionally, this work served as a comparison between UXClumpy and RXTorusD. We found broad agreement between the two, with 8/11 sources agreeing on the value of the photon index Gamma, while only 5/11 sources agreeing on the NH,los value within the 90% confidence level.

Aims. We aim at deriving stellar atmospheric parameters based on the photometric data from the Javalambre Photometric Local Universe Survey (J-PLUS) in addition to near-infrared photometry from the Two Micron All-Sky Survey (2MASS). Methods. Our method consists of a semi-supervised machine learning approach based on the k-means method combined with a modified k-nearest neighbors algorithm. This method compares the observed photometry to a set of reference data to estimate the stellar effective temperature ($T_{\rm eff}$), surface gravity ($\log{g}$), and metallicity ([Fe/H]) of stars from J-PLUS Data Release 3 (DR3). Results. We estimated $T_{\rm eff}$, $\log{g}$, and [Fe/H], for approximately 5.6 million stars from J-PLUS DR3, along with their this http URL results were in agreement with spectroscopic estimates from LAMOST and this http URL also applied a dimension reduction method, seeking greater efficiency by reducing the computation time and minimizing the needed information for calculating the stellar parameters, resulting in a subset of 11 colors. From this approach, stellar parameters were obtained for approximately six million stars. Conclusions. Our results demonstrated the potential of using a method built from machine learning algorithms that do not require prior training. Additionally, it was shown that the proposed method allowed estimating reliable atmospheric parameters even when the available photometry did not fulfill all photometric quality criteria. We defined a neighborhood parameter, which assesses the reliability of our estimations and indicates that objects with smaller neighborhoods values have lower uncertainties.

A quantitative understanding of cometary outbursts requires robust constraints on the size distribution of ejected particles, which governs outburst dynamics and underpins estimates of released gas and dust. In the absence of direct measurements of particle sizes, assumptions about the size distribution play a central role in modelling dust-trail formation, their dynamical evolution and observability, and the potential production of meteor showers following encounters with Earth. We analyse brightness amplitude variations associated with outbursts of comet 17P/Holmes from 1892 to 2021, with particular emphasis on the exceptional 2007 mega-outburst. During this event the comet underwent a rapid and substantial brightening; at its peak, the expanding coma reached a diameter larger than that of the Sun and briefly became the largest object in the Solar System visible to the naked eye. We constrain the size distribution and total mass of porous agglomerates composed of ice, organics, and dust ejected during the outburst. The inferred particle size distribution is consistent with a power law of index q, yielding effective particle sizes between 1.15 x 10^-6 m for q = 4 and 5 x 10^-3 m for q = 2. Accounting for effective particle size, sublimation flux, and bulk density, we find that the total number of ejected particles increases with both q and sublimation flux. These results place quantitative constraints on the physical properties of outburst ejecta and provide physically motivated initial conditions for long-term dust-trail evolution modelling, relevant to the origin of meteoroid streams and the interplanetary dust population.

Gravitational lensing offers unique insights into cosmology by bending light around massive objects. Strong gravitational lensing, in particular, produces magnified and often multiple images of distant sources, crucial for precise cosmological measurements and understanding the distribution of dark matter in the universe. Current studies are limited by the number of strong gravitational lenses. From upcoming cosmological surveys, we anticipate observing a several orders of magnitude increase in the number of lenses, for both static and transient phenomena. However, detecting and analyzing these events from vast surveys like Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) presents significant challenges. To prepare for these challenges, we introduce SLSim, a versatile simulation tool tailored for the Vera C. Rubin Observatory. SLSim integrates advanced astrophysical models with computational efficiency to generate synthetic strong lens populations under realistic observational conditions. SLSim simulates static and variable lensing scenarios, essential for cosmological studies, training and testing lens search and data analysis pipelines. This paper details SLSim,'s design and implementation, emphasizing its modularity and capabilities across various astrophysical regimes. Validation against observational data and existing simulations confirms SLSim's accuracy in reproducing observed lensing phenomena. SLSim is publicly available at this https URL, and we anticipate continued development and expansion of its capabilities. Users are encouraged to check the repository for updates and to contribute to ongoing community efforts in strong lensing simulations.

We discuss in some details a novel algorithm for performing partial-sky spherical harmonic transforms (SHT), building on the Fourier-sphere method of Reinecke et al (2023) handling efficiently high numbers of arbitrary locations on the sphere. Our main motivations are Cosmic Microwave Background lensing from the South Pole Telescope, and the South Pole Observatory program targeting primordial gravitational waves from inflation, requiring high-resolution, numerically intensive work on small sky fractions. We achieve speed-up factors ranging from 3 to 10 on SPT-3G main field and BICEP3 deep footprint, and much more on smaller patches. More generally, the algorithm eliminates in our case study the usual disadvantages of arbitrary pixelisations in comparison to isolatitude pixelisations or flat-sky approximations, making it ideal for ambitious workflows that require repeated SHTs on limited sky regions.

We apply two variants of Physics-Informed Neural Networks (PINNs) to reconstruct the Type Ia supernova absolute magnitude $M_B(z)$ from joint BAO and supernova data under four cosmological models ($\Lambda$CDM, CPL, GEDE, $\Lambda_s$CDM) and two DESI DR2 fiducial sets. A heteroscedastic single-network method tested across four constraint configurations establishes that the Etherington distance duality relation is more fundamental constraint than cosmological model priors, with DDR violations of 30--52 mmag under physical constraints versus 85--2330 mmag without. Under full constraints all models recover $M_B \approx -19.3$ mag with biases below 0.05 mag. A Fisher information-weighted two-network variant trains independent networks on BAO and SN data, providing clean probe separation and finding no significant $M_B$ evolution in $z \in [0.3, 1.5]$. The heteroscedastic method identifies a persistent $2-3\sigma$ residual at $z \sim 0.4-0.5$ that is consistent across all four models and both fiducials; the Fisher method finds no significant pointwise deviation in $z\in[0.3,1.5]$ but shows a systematic separation of redshift-binned $M_B$ distributions consistent with the same underlying tension. While the origin of this feature remains ambiguous, its model-independence and cross-method consistency warrant further investigation with forthcoming data.

Clumping by streaming instability (SI) leading to gravitational collapse is the leading proposed mechanism for forming planetesimals, the building blocks of terrestrial planets and giant-planet cores. The critical dust-to-gas density ratio above which the SI leads to dust concentration strong enough to result in collapse depends on local dust properties and disk conditions, such as particle Stokes number, pressure gradient, and turbulence. The role of turbulence has recently drawn attention because simulations have shown that even modest levels of istropically forced turbulence can significantly increase the critical dust-to-gas ratio. However, we show that this does not hold for turbulence self-consistently generated by the magnetorotational instability (MRI). We present the first parameter study of the SI in three-dimensional, stratified, shearing-box simulations including non-ideal magnetohydrodynamics with ambipolar diffusion. Modest turbulence yields a clumping boundary similar to pure SI cases, while stronger turbulence does increase the critical dust-to-gas density ratio, though less than in the models where turbulence is isotropically forced. Particle concentration occurs inside zonal flows, large-scale structures generated by the MRI. Our results suggest that self-consistent, MRI-driven turbulence does not necessarily inhibit planetesimal formation.

The Sagittarius C (Sgr C) complex, located on the western edge of the Central Molecular Zone (CMZ), hosts a mixture of star-forming and non-thermal activity whose X-ray properties remain poorly understood. Using deep archival Chandra and XMM-Newton observations, we resolve the diffuse X-ray emission in Sgr C into two components: an H II region coincident with the radio peak and a brighter diffuse feature located to its southwest. Spatially resolved spectroscopy reveals the presence of a soft (kT <= 1 keV) plasma with metal abundances consistent with the elevated metallicity expected in the CMZ in both regions, along with a harder (~ 8 keV) thermal component within the H II region. The observed diffuse X-ray emission and its association with an expanding [C II] shell suggest that the hot gas may originate from a young supernova remnant (SNR) embedded in the H II region. Under this interpretation, the inferred shock velocity (~ 800 km/s) and SNR age (>= 1.7 kyr) are consistent with a core-collapse SNR in the Galactic Center. These results reveal Sgr C as a potential host of a SNR and highlight the complex interplay between massive-star feedback, magnetic fields, and molecular gas in the CMZ.

We report the stereoscopic observations of two recurrent streamer waves in a single streamer structure, utilizing coordinated observations from the SOHO, STEREO, and SDO missions. Contrary to the long-held view that fast coronal mass ejections (CMEs) are necessary drivers, we demonstrate that these recurrent waves were excited by two consecutive slow CMEs (<500 km/s} accompanied by only modest flare activity. Three-dimensional reconstruction reveals that the first and second waves propagated with significant decelerations of - 7.93 and - 10.26 m s^-2, respectively. Their average amplitudes were 0.41 and 0.77 solar radii, wavelengths were 4.02 and 6.17, and periods were 2.66 and 2.53 hours, respectively. While the amplitude of the first wave declined with heliocentric distance (consistent with conventional energy convection), the second wave exhibited an intriguing increasing trend in amplitude. Both waves showed a linear increase in wavelength and period with distance, indicating a non-stationary and dispersive medium. Crucially, despite the disparity in driver energy and wave scales, the periods and their change rates remained nearly identical for both events. This provides compelling case-specific evidence that the streamer wave period is primarily determined by the inherent eigenmodes of the streamer plasma slab rather than the specific characteristics of the trigger. We conclude that the generation of observable streamer waves is a combined consequence of the streamer's structural stability and the energy transfer efficiency of the triggering disturbance.

High-mass stars form in protoclusters, where gravo-magnetic processes shape collapsing clouds and clumps to be elongated preferentially perpendicular to magnetic (B) fields. Yet it remains unclear whether gravo-magnetic processes still govern the formation of smaller-scale condensations in massive-star-forming protoclusters, which are crucial for understanding the stellar initial mass function and multiplicity. Here we report the first statistical evidence that the condensation elongations are preferentially aligned with local B fields, based on high-resolution data from the largest dust polarization survey toward 30 massive star-forming regions with the Atacama Large Millimeter/submillimeter Array (ALMA). Our clustered massive star formation simulations reveal that this more parallel alignment is exclusively observed in models where initial turbulence dominates B fields. In contrast, models with initial B fields dominating turbulence distinctly exhibit a more perpendicular alignment. The comparison between observations and simulations suggests that turbulence could play a more important role than B fields in the formation of condensations in the context of clustered massive star formation, contradicting the prediction of classical magnetically regulated models. Moreover, we find a possibly turbulence-induced preferential misalignment between the B field and rotation axis of condensations, which may potentially reduce the magnetic braking efficiency and facilitate the formation of large protostellar disks.

NGC 1566 has exhibited dramatic state changes in its X-ray spectrum, but the evolution of its broadband timing properties remains poorly constrained. We combine long-term Swift monitoring with high-time-resolution XMM-Newton observations to model the broadband X-ray power spectral density (PSD) in the dim and bright states. In the hard band, the PSD bend frequency shifts by about 1 dex between the two states, implying a substantially longer characteristic variability timescale in the bright state. The relative timing behaviour of the soft and hard bands also changes with state. In the dim state, the soft-band bend frequency is higher than the hard-band value by about 0.49 dex, whereas in the bright state the two become broadly consistent. The broadband variability evolution of NGC 1566 therefore involves not only an overall shift in characteristic timescale, but also a state-dependent change in the soft-hard timing relation, from a more stratified to a more tightly coupled configuration. Combined with previous spectral results, this supports a genuine reconfiguration of the inner radiative structure during the changing-look transition.

Changing-look active galactic nuclei (CL AGNs) show large changes in luminosity and optical spectral state on time-scales of a few years, and provide a valuable probe of time-dependent accretion in the disc-BLR-torus system. We present a systematic statistical study of their optical variability in a well-defined Type-1 phase, using g- and r-band light curves from the Zwicky Transient Facility for 165 CL AGNs. A subsample of 34 objects also has NEOWISE W1 and W2 light curves, which we use to measure optical-mid-infrared time lags. We use structure functions and a damped random-walk model to characterize variability amplitudes and time-scales on rest-frame scales from tens to a few hundred days, and examine their dependence on black hole mass, luminosity, and Eddington ratio. In the Type-1 phase, the short-time-scale optical variability amplitude on about 30-day time-scales shows little dependence on black hole mass, luminosity, or Eddington ratio. By contrast, the longer-term amplitudes on 150-300 day time-scales, as well as the damped random-walk time-scales, increase slowly with black hole mass and luminosity, but still show no clear dependence on Eddington ratio. The sample shows a ubiquitous bluer-when-brighter trend and larger variability at shorter wavelengths, consistent with continuum variability from a multi-temperature accretion disc. For the NEOWISE subsample, the dust lag-luminosity relation inferred from the optical-mid-infrared lags is similar to that of normal Type-1 AGNs. Overall, CL AGNs in the Type-1 phase behave like normal Type-1 AGNs within the standard disc-BLR-dusty torus framework, but are more prone to large continuum reconfigurations on year-like time-scales.

The present article is written in the wake of a recently published study of the relation between the light curves of Long Period Variables and their evolution along the Asymptotic Giant Branch (AGB). It introduces a pair of new parameters that describe the shape of the ascending branches of such light curves. This parameterization reveals strong correlations with other parameters describing the evolution of the star on the AGB: periods, regularity and amplitudes of the oscillations, effective temperatures, mass loss rates, carbon and oxygen isotopic ratios, colour indices. It sheds new light on the occasional presence of humps on the ascending branches and on the distinction between stars that have not experienced strong Third Dredge Up (TDU) events and those that have as well as between oxygen-rich and carbon-rich stars. One of the new parameters, referred to as q, is particularly efficient at tracking the evolution of the star along the AGB. Globally, a simple picture can be drawn in the plane spanned by the period and by q. Yet, many details remain unexplained when looking at this picture in finer details. Overall, the results presented in the article help significantly with clarifying the complex set of observations that have been made in this domain and should inspire new considerations on their relation with the underlying physical mechanisms at stake inside the stars.

We present a bar-informed kinematic-distance (BIKD) method to reconstruct face-on molecular-gas maps of the inner Milky Way from PPV data, relaxing the standard assumption of axisymmetric circular rotation that can generate severe artifacts in barred regions. BIKD replaces the rotation curve with a non-axisymmetric streaming field extracted from hydrodynamical simulations in an observationally constrained barred Galactic potential, and infers a discrete distance posterior along each sightline using a Gaussian likelihood in line-of-sight velocity. To mitigate multi-modality, we adopt posterior-weighted map making via posterior sampling. We validate the full pipeline in closed-loop tests on the simulations, showing that the recovered large-scale morphology is only weakly sensitive to simple distance priors and remains stable across plausible variations in bar angle, snapshot time, and pattern speed. We then apply BIKD to a Galactic CO survey to obtain a face-on $\Sigma$ map. Compared to a standard axisymmetric kinematic-distance (KD) reconstruction, BIKD strongly suppresses line-of-sight--elongated finger-of-God features and robustly recovers a bar-aligned, quadrant-asymmetric inner-Galaxy morphology under model marginalization. The model-marginalized radial profiles show an approximately exponential decline beyond $\sim4$ kpc, a pronounced deficit at $R\sim0.5$--$3.5$ kpc, and a central concentration consistent with Central Molecular Zone surface densities. Finally, we compare prominent ridge-shaped overdensities in the BIKD map with independent spiral-arm loci traced by high-mass star-forming region masers with VLBI trigonometric parallaxes and by classical Cepheids with period--luminosity distances. Several maser-parallax segments are qualitatively consistent with the dominant BIKD ridges, whereas the Cepheid loci do not coincide with them within their recommended azimuth range.

Large astronomical instruments using tens to hundreds of optical or infrared science detectors pose specific challenges for detector control, where, in addition to performance, other engineering aspects like scalability, power consumption, size, weight and programmatic aspects such as cost and sustainability need to be considered. In this paper we analyze the approach existing instruments have taken for detector control. We focus this analysis on recent ground based astronomical instruments using 10 or more detectors for science imaging or spectrography. From this analysis we identify key technologies, like cryogenic electronics, Ethernet based interfaces and fully-digital detectors, for implementing efficient control of many detectors. We also propose a concept joining all identified technologies that could be considered for future large ESO instruments as a complement of ESO's general detector controller, NGCII.

Accurate modeling of supernova (SN) feedback in galaxy formation simulations is complicated by violations of energy conservation arising from the vector nature of momentum injection. We present a new mechanical feedback scheme that addresses two sources of such violations: the relative motion between gas elements and the SN-hosting star particle, and multiple momentum injections into a single gas element within one timestep. By computing the kinetic energy increment in the rest frame of the gas element, our method ensures energy conservation while avoiding inversion of the momentum increment that can occur in the lab frame. This correction, however, inherently violates momentum conservation, which can disturb angular momentum distribution and hinder disk formation when momentum is coupled on galactic scales. To prevent unphysical large-scale coupling for SNe in low-density environments without introducing an ad hoc maximum radius, we switch to purely thermal feedback when the cooling radius is resolved by the local inter-element separation. Using cosmological zoom-in simulations of dwarf galaxies with halo masses $M_\mathrm{vir} \sim 10^{11},\mathrm{M}_\odot$ at two resolutions differing by a factor of eight, we show that our scheme achieves good convergence in star formation histories. Without the correction for multiple injections, stellar mass in low-resolution runs can drop to 59% of that in high-resolution counterparts, worse than in our fiducial scheme. At feedback strengths reproducing dwarf galaxy stellar masses, a Milky Way-mass galaxy simulation ($M_\mathrm{vir} \sim 1.8\times10^{12},\mathrm{M}_\odot$) overproduces stellar mass, suggesting additional feedback such as AGN feedback is required.

We present a novel approach to correcting H$\alpha$ luminosity functions for dust extinction by calibrating against radio-based star formation rates (SFRs), using data from the Evolutionary Map of the Universe (EMU) and Galaxy and Mass Assembly (GAMA) surveys. Accurate dust correction is essential for deriving SFRs from rest-frame UV-optical emission lines, particularly as the \textit{James Webb Space Telescope} extends such measurements to galaxies at $z>5$. While a luminosity dependence of dust obscuration has long been recognised, our method exploits the empirical relationship between obscured (H$\alpha$) and unobscured (radio) SFRs to provide a dust correction that can be applied where traditional spectroscopic techniques, e.g. Balmer line based approaches, are unavailable. We apply the SFR based dust correction to 25 published H$\alpha$ luminosity functions spanning $0<z<8$, and derive corresponding star formation rate densities (SFRDs). Adopting the locally calibrated H$\alpha$--radio relation ends up with an overestimate of the cosmic SFRD by more than two orders of magnitude at $z\gtrsim1$. Motivated by the luminosity dependent relation in the local Universe, we introduce a new model where the luminosity dependence of the dust obscuration decreases with increasing redshift. This approach can reproduce observed SFRDs across cosmic time. These results highlight the potential of a radio-based calibration for dust correction, where a luminosity dependent correction would need to decline in strength with increasing redshift. This implies that the dust content or distribution in galaxies at early epochs differs substantially from that in the local Universe.

We present a comprehensive pipeline developed for the image processing of the KMTNet Synoptic Survey of the Southern Sky (KS4) Data Release 1. This pipeline encompasses several key processes, including data quality assurance, astrometry, photometric zero-point (ZP) calibration, bad pixel masking, image stacking, and difference image analysis (DIA). The astrometric solutions were validated by cross-matching with the Gaia EDR3 catalog, achieving sub-pixel astrometric accuracy (< 0.4 arcsec). To ensure spatial consistency, we divided each image into multiple subsections and confirmed that astrometric accuracy was maintained even at the edges. We performed a two-stage photometric calibration. Initial ZP solutions were computed for each individual image frame using the APASS DR9 and SkyMapper DR3 catalogs. Subsequently, we corrected residual spatial variations in the stacked images using Gaia XP photometry. This procedure yielded a 5-sigma depth of 22-23 AB mag across the BVRI bands, with root-mean-square errors of approximately 0.03 mag when referenced to Gaia stars in the magnitude range of 14-19 mag. The processed KS4 images span over 4,000 deg^2 of the southern sky, providing reference images suitable for DIA. This publicly available pipeline also supports real-time processing of newly acquired images, enabling prompt transient detection. We demonstrate its effectiveness through successful applications in gravitational-wave follow-up observations.

Based on multi-frequency radio polarization survey datasets, we investigate the spectral characteristics of the Galactic interstellar medium (ISM) using the polarization frequency analysis (PFA) method, referred to as polarization variance. By comparing this novel PFA technique with the traditional power spectrum approach, and by cross-examining data from two distinct surveys, we aim to reinforce the robustness of our findings. Our analysis reveals that the ISM scaling slope in the Galactic disk is steeper than the classic Kolmogorov slope, whereas the ISM scaling slope in the Galactic halo aligns with the Kolmogorov slope. We suggest a distinct turbulence cascade process operating in the Galactic halo compared to the Galactic disk.

In this letter, we propose a single-field inflation model that realizes a slow-roll-to-ultra-slow-roll transition while keeping the second slow-roll parameter smoothly varying throughout. The model is built through a minimal modification by introducing a simple time dependence in the effective mass term of the Mukhanov-Sasaki equation. We obtain fully analytical solutions for both the background evolution and the curvature perturbations, which makes the parameter dependence of the curvature power spectrum easy to track. To the best of our knowledge, this is the first analytical model that describes a smooth transition of this kind. We also compare its signatures with those of the corresponding sharp-transition counterpart.

Magnetic fields play a crucial role throughout stellar evolution, regulating angular momentum, channelling accretion, and launching jets and outflows. While the magnetic properties of Classical T Tauri Stars (CTTS) are well characterised, those of their progenitors, Class I and Flat-Spectrum (FS) protostars, remain poorly constrained due to observational challenges linked to their embedded nature. We aim to detect and characterise large-scale magnetic fields in a sample of Class I and FS protostars, which are expected to host strong dynamo-generated fields. Using SPIRou, a high-resolution near-infrared spectropolarimeter, we analysed polarised spectra and applied the Least Squares Deconvolution (LSD) technique to extract magnetic signatures and measure longitudinal fields from Stokes V profiles. We report new detections of large-scale magnetic fields in 5 FS protostars. Including the previously known magnetic FS protostar V347 Aur, 40% of our sample (15 objects) is confirmed to be magnetic. These stars exhibit clear Zeeman signatures, with longitudinal field strengths ranging from ~80 to ~200 G. The remaining targets show no detectable Stokes V signature, with upper limits on dipolar fields between 500 G and >5 kG. These results indicate that Class I and FS protostars can host large-scale magnetic fields, possibly weaker than in CTTS, supporting the idea that magnetic processes are already active during the main accretion phase and may influence star-disk interactions from the earliest stages.

Context. Gamma-ray bursts (GRBs) reach redshifts beyond Type Ia supernovae (SNe Ia) and can extend distance measurements into the early Universe, but their use as distance indicators is limited by the circularity problem in calibrating empirical luminosity relations. Aims. We present a model-independent methodology to overcome this circularity by combining Pantheon$+$ SNe Ia, a distance reconstruction based on artificial neural networks (ANNs), and two GRB correlations (Amati and Combo) into a distance ladder from low to high redshift, with the goal of constraining cosmological parameters in $\Lambda \mathrm{CDM}$ and $w_0 w_a \mathrm{CDM}$. Methods. We use the ReFANN to reconstruct the luminosity distance $d_L(z)$ and distance modulus $\mu(z)$ from the Pantheon$+$ dataset, with hyperparameters optimized via approximate Bayesian computation rejection and a risk function. This model-independent reconstruction calibrates the Amati and Combo relations using a low-redshift ($z<1$) GRB sample from Fermi GBM and Swift-XRT. The calibrated relations then provide distance estimates for GRBs at $z \geq 1$. Finally, a joint Bayesian analysis simultaneously constrains the cosmological and GRB correlation parameters, ensuring self-consistent uncertainty propagation. Results. We obtain consistent cosmological constraints from two independent GRB correlations. The Hubble constant $H_0$ agrees with SNe Ia values, though potentially influenced by Pantheon$+$ dataset. High-redshift GRBs favour a higher matter density $\Omega_m$ than the Pantheon$+$ and hint at possible dark energy this http URL. We present a framework that mitigates GRB cosmology's circularity problem, extending the distance ladder to $z \sim 9$ and establishing GRBs as a high-redshift probe.

Discoveries of ultra-massive magnetic white dwarfs (WDs) and peculiar pulsars have been proposed to originate in double white dwarf (DWD) mergers. There are three possible post-merger central remnants of non-explosive mergers: 1) a stable sub-Chandrasekhar WD; 2) a rapidly rotating super-Chandrasekhar WD; 3) a neutron star (NS). In this work, we explore the thermal transient arising from non-explosive DWD mergers that leave an NS remnant from the prompt collapse of the merged core. The transient is powered by the cooling of the expanding dynamical ejecta, with energy injection from magnetic dipole radiation, which depends on the dipole factor $D = B_d^2/P_0^4$, with $B_d$ and $P_0$ being the surface magnetic field strength and initial rotation period of the newborn NS. We simulate lightcurves in the Legacy Survey of Space and Time (LSST) bands and estimate the horizon and detection rates for these transients across a range of model parameters. We find LSST detection horizons upper limits ranging $30$--$1020$ Mpc and corresponding detection rates $10^2$--$10^6$ yr$^{-1}$ for $\log D = 24$--$40$. Accounting for the survey cadence, we find that only configurations with $\log D = 36$--$40$ are detectable within $240$--$990$ Mpc, with detection rates $10^4$--$10^6$ yr$^{-1}$. Combined searches across surveys can compensate for the low cadence and improve the detection rates of fast and less energetic sources. Multi-wavelength campaigns can aid in detecting the spindown radiation at higher energies observable after the optical transient. Observations of these transients will provide direct evidence of the non-explosive DWD mergers, characterise the remnants and progenitor parameters, and the fraction of explosive and non-explosive mergers.

Pulsar wind nebulae (PWNe), formed when the wind originating from a rapidly rotating neutron star flows out into its surroundings, have now been observed across the electromagnetic spectrum from the radio to the PeV gamma-ray regime. For most of these sources, leptonic processes, where electrons interacting with background photon fields produce high-energy photons through inverse Compton scattering, are believed to be the origin of associated very-high-energy gamma-ray emission. As such, these objects cannot contribute significantly to the galactic hadronic cosmic ray flux at ~TeV-PeV energies. However, in a handful of cases, the possibility for an energetically sub-dominant hadron population being accelerated and producing very to ultra-high energy gamma-rays through pion decay has not yet been comprehensively excluded. Such scenarios have received renewed attention in the light of recent results from the Large High Altitude Air Shower Observatory (LHAASO). In this review we explore the theoretical background positing hadronic acceleration in galactic PWNe, considering cases where the hadrons escape from the pulsar surface and/or are accelerated in the wind, as well as potential 'shock mixing' scenarios. We also explore current and future possible constraints on a hadronic component to PWNe from observations.

We compile a systematic mass inventory of the Solar System excluding the Sun, drawing on spacecraft measurements, planetary ephemerides, and population surveys of small-body populations including main-belt asteroids and trans-Neptunian objects. Using a Monte Carlo simulation with 100,000 realisations, and treating poorly constrained components (scattered disc, Oort cloud) as log-normal distributions, we obtain a total non-solar mass of 462 Earth masses (median), with a 68% credible interval of [451, 515] Earth masses and a 90% credible interval of [449, 642] Earth masses. The giant planets dominate the mass budget (96.2% of the total). A variance decomposition shows that 98.2% of the total uncertainty is attributable to a single component: the inner Oort cloud (Hills cloud), for which no direct observational constraints exist. The current small-body populations retain only ~0.2% of the primordial trans-Neptunian disc mass inferred from Nice model simulations, and ~0.04% of the primordial asteroid belt mass implied by the Grand Tack hypothesis. We identify constraints on the Oort cloud from the Vera C. Rubin Observatory and improved long-period comet surveys as the primary path toward a better-determined total mass budget.

The pulsar timing array systems have reported a detection of a nanohertz-band stochastic gravitational wave background in our galaxy. It is of interest to use this observation to probe modified gravity and to forecast the sensitivity with which certain deviations can be tested in the coming years. In this paper, we focus on the modified dispersion relation of the tensor modes and its effect on the overlap reduction function of the timing residual cross-correlations. We perform a comprehensive forecast of the phase velocity uncertainty, $\sigma_v$, using a Fisher analysis validated by a mock-data study to account for potential non-Gaussian behavior. We also take into account the sample variance effect and provide an observational timeline for future PTA sensitivity: detecting a $10\%$ or $-1\%$ deviation from the speed of light at the $3\sigma$ level requires $\mathcal{O}(30)$ years of observations.

We present high-speed photometry of the eclipsing cataclysmic variable CSS131106 J052412+004148. We determine the system parameters by modelling the eclipse lightcurve using the photometric eclipse method, in which the mass ratio is determined from the relative timings of the white dwarf and bright spot eclipses. Despite the blended white dwarf and bright spot ingress, typical of longer period cataclysmic variables, we perform simulations that show we are able to reliably constrain the component masses. We find a mass ratio of $q = 0.81 \pm 0.06$ and inclination $i = 78.5 \pm 0.7$ degrees. The white dwarf and donor masses were found to be $M_{w} = 0.72 \pm 0.04 \, M_{\odot}$ and $M_{d} = 0.58 \pm 0.06 \, M_{\odot}$ respectively. The white dwarf temperature was estimated to be $T_{\rm eff} = 18~500 \pm 2~000$ K, implying a moderate accretion rate of $\dot{M} = 3 \pm 1 \times 10^{-10} M_{\odot}$ yr$^{-1}$. The donor in CSS131106 J052412+004148 joins two other long-period cataclysmic variables (IP Peg and HS 0220+0031) in being unusually small for its mass, even when compared to detached M-dwarfs. The donors in all three systems are also unusually cool for their mass. We discuss possible explanations for the small radii and cool temperatures of the donors in these systems, but find no viable explanation for their properties.

High-resolution spectroscopy provides unique constraints on exoplanet atmospheric composition and dynamics. The past decade of ground-based campaigns has accumulated extensive public archives, yet many observations remain unanalysed. We present a homogeneous blind-search analysis of 50 SPIRou transits spanning 14 exoplanets, ranging from super-Earths to ultra-hot Jupiters, combining data from large program and public archived observations. Using automated data reduction and atmospheric retrieval via Nested Sampling validated by Cross Correlation Function analysis, we confirm previous H2O and CO detections in HD 189733 b, WASP-76 b, and WASP-127 b, report tentative H2S detections in HD 189733 b and TOI-1807 b, tentative detection of GJ 3470 b's atmosphere, and provide upper limits for non-detections. This work demonstrates a scalable method for systematic archive analysis, providing a first step toward ground-based support of large space-based atmospheric characterization programs and the study of atmospheric diversity across exoplanet populations from a statistical perspective.

In this third study of the 'Resolving supermAssive Black hole Binaries In galacTic hydrodynamical Simulations' (RABBITS) series we develop and implement a geometrically thin relativistic accretion disc model, which self-consistently evolves the mass and spin vector of black holes via analytically modelling the structure of steady-state accretion discs. The model employs a suite of relativistic, local solutions where pressure is dominated by either gas or radiation, while opacity is primarily governed by either electron scattering or free-free absorption. These local solutions are piece-wisely combined to form the global structure of the accretion disc based on each solution's range of validity. By explicitly modelling the structure of accretion discs, the model mitigates the stochasticity inherent in Bondi-type prescriptions, resulting in an approach where every episode of black hole mass accretion is derived from first principles. For the first time, our model enables galaxy formation simulations to place constraints on accretion disc sizes and structures. In addition, flux and temperature radial profiles can be directly extracted from the simulation, enabling the generation of spectral energy distributions. Consequently, by incorporating the thermal structure and spacetime geometry around spinning black holes, our model more accurately captures the energetic output of quasars, overcoming critical limitations of classical approaches. Along with this manuscript, we make public a C version of the model appropriate to be used as a module in simulations, a Python version of the model that can be used independently to post-process any simulation and build mock accretion discs, and an updated version of the Relagn model that has the capability of producing SEDs by building an accretion disc for a given set of parameters and extracting its surface density, temperature, and opacity profiles.

In previous work, it was reported that the Galactic black hole candidate MAXI J1810-222 exhibited a notable absorption spectral feature at around 1 keV in low-resolution X-ray spectra of CCD-like detectors. The feature was correlated with the spectral state of the source, being stronger in the soft states, as it occurs in the typical Fe K winds of X-ray binaries (XRBs). However, the results hinted towards rather extreme wind velocities of up to ~0.1 c. We therefore requested and obtained an observation with XMM-Newton to take advantage of the 10-fold higher spectral resolution (R ~200-400) provided by the RGS detector in order to resolve the lines and break the degeneracy between different models and interpretations. We applied state-of-the-art models of plasma in photoionisation equilibrium and multiphase interstellar medium. Further comparisons are performed with a re-analysis of NICER and NuSTAR data. The XMM-Newton/RGS spectrum is consistent with the presence of a mildly relativistic wind, confirming the earlier indications obtained with NICER, but places tighter constraints on the outflow properties, with the lines being intrinsically broad. The data would then favour magnetically driven winds, although thermal effects may still contribute to mass loading. NuSTAR and XMM-Newton (EPIC) show a further hotter component indicating a stratified or multiphase outflow. Fe K spectra taken with calorimetric detectors (e.g., Resolve on XRISM) will enable a high-resolution view of the complex extreme outflow in this source and shed new light on outflow processes in XRBs.

The association of persistent radio sources (PRSs) with repeating fast radio bursts (FRBs) offers unique insights into their circum-burst environments. Building upon the physical link between PRS luminosity ($L_\nu$) and FRB rotation measure (RM), we introduce a novel diagnostic framework utilizing the intrinsic scatter of the $L_\nu - |{\rm RM}|$ relation as a physical probe of nebula dynamics. We demonstrate that this scatter encodes critical information regarding the temporal evolution of the nebula radius ($R \propto t^\alpha$). By deriving a generic scaling $L_\nu \propto R^\epsilon |\mathrm{RM}|$ and analyzing the residuals of the five confirmed FRB-PRS systems, we constrain the nebula's evolutionary index to $\alpha|\epsilon| = 1.5 \pm 0.7$ (1$\sigma$ uncertainty). This measurement provides a powerful diagnostic tool for distinguishing among different astrophysical scenarios. Its value deviates from the expectations for supernova remnants (SNRs) in the Sedov-Taylor phase ($\alpha|\epsilon| \sim 0.2-0.4$), reverse shocks during the free-expansion phase of SNR/interstellar medium (ISM) interactions ($\alpha|\epsilon| \gtrsim 3.5$), and pulsar wind nebulae (PWNe) powered by a decaying wind ($\alpha|\epsilon| \sim 0-0.15$). Instead, it is more consistent with forward shocks in the free-expansion phase of both SNR/ISM and PWN/SNR systems ($\alpha|\epsilon| \sim 2.0-2.8$), and young PWNe driven by a nearly constant wind ($\alpha|\epsilon| \sim 1$). These findings suggest that active repeaters are powered by dynamically young, rapidly expanding nebulae. While currently limited by the small sample size, this framework establishes a robust methodology for future population studies to constrain the physical origin of PRSs.

This work explores the differences between static and dynamically evolving physico-chemical models of pre-stellar cores. A 3D MHD model of a pre-stellar core embedded in a dynamic star-forming cloud is post-processed using sequentially dust radiative transfer, a gas-grain chemical model, and a non-LTE line-radiative transfer model. The chemical evolution is modeled along $\sim$20,000 tracer particle trajectories to capture the impact of a realistic dynamical evolution as the core is formed. The emission morphology of CH$_3$OH and $c$-C$_3$H$_2$ and the intensities of CH$_3$OH, $c$-C$_3$H$_2$, CS, SO, HCN, HCO$^+$ and N$_2$H$^+$ are compared with observations of L1544. Our results show a distinct difference in chemical morphology between the dynamical and static models. The dynamical model reproduces the observed spatial distribution of CH$_3$OH and $c$-C$_3$H$_2$ toward L1544, whereas the static model fails to reproduce this morphology. In contrast, when comparing modeled and observed intensities across a broad range of molecules, the static model shows good agreement with observations for L1544. The dynamical model systematically predicts lower abundances and modeled intensities for six of the seven species presented here. For sulphur-bearing species, the intensities are in better agreement with observations when the initial abundances are undepleted in heavier elements. This study reveals distinct differences between dynamical and static physico-chemical models. The static model predicts higher abundances and intensities for the majority of the molecules studied here, compared with the dynamical model. This discrepancy may stem from the specific choices of initial conditions, which could limit the dynamical models ability to fully capture the physical and chemical history. The intensities predicted by the static model are comparable to those observed toward L1544.

Gravitational wave astronomy is rapidly advancing with the development of new observatories, leading to an increasing volume and complexity of data. This trend places growing pressure on classical data analysis methods and motivates the exploration of quantum approaches. In this work, we introduce a quantum matched filtering framework for gravitational-wave detection based on the Long algorithm, marking its first application to the gravitational-wave data analysis. Numerical simulations show that the proposed approach preserves the quadratic speedup of quantum search while exhibiting significantly improved robustness, thereby overcoming key limitations of the Grover-algorithm based methods.

Interstellar dust has been detected in situ flowing through the heliosphere. Understanding the implications of this dust for the nature of interstellar dust in the very local interstellar medium requires modeling the transport of the grains as they interact with the solar wind magnetic field. The magnetic field in the sector region (SR) that contains the heliospheric current sheet is substantially different from that in the monopolar solar wind. The rapid polarity flips that occur in the SR can present an effectively very low averaged field strength to grains that have gyroradii of tens of au. We present new calculations of dust transport through the heliosphere using a model that includes the SR. We show that the SR can act as a window allowing even relatively small grains to penetrate deep into the heliosphere. The presence of the SR reduces the variation in dust density with the solar cycle (as compared to models without it), with very little concentration or dilution of the dust for grains larger than $\sim 0.1$ $\mu$m for most of the solar cycle (except for a focusing overall polarity of the field at solar minimum.) While the lack of time dependence of the magnetic field during transport of grains through the heliosphere is a limitation of the model, the relative lack of variation as a function of the point in the solar cycle of the grain density in the inner heliosphere suggests that our results will not deviate dramatically from a model that fully incorporates time dependence.

We consider the Gauss-Bonnet term coupled to the inflaton in the Palatini formulation of gravity. Unlike in the metric formulation, the Gauss-Bonnet term is not always a total derivative. We solve for the connection and insert it into the action, exactly for the spatially flat FLRW spacetime, and using the gradient approximation and order reduction for a general spacetime. We consider three cases: when the connection is unconstrained, and when non-metricity or torsion is put to zero. In all cases, the leading order change to the inflaton kinetic has the same form as that generated by the Chern-Simons term, but a negative sign. The modification of the gravitational wave sector also has the same form as in the Chern-Simons case but with a negative sign, except possibly for zero torsion, depending on the coupling and the potential. Within the range of validity of our approximations, differences from the metric formulation are small unless the kinetic term flips sign or is close to doing so.

Modifications to Newtonian dynamics at low accelerations have long been proposed as an alternative to dark matter to explain galaxy rotation curves. More recently, similar corrections have been invoked to interpret anomalies in Cavendish-type laboratory experiments and in the dynamics of wide binary stars, although the latter remain affected by ongoing observational debate. We show that, if deviations from Newtonian gravity occur in the low-acceleration regime, the available data are broadly consistent with a MOND-like interpretation. In this framework, wide binary systems appear to extend the Tully-Fisher relation, well established for galaxies, to much smaller mass scales. Taken together, departures from Newtonian predictions at low accelerations in galaxies, wide binaries, and laboratory experiments may point to a common physical scenario.

There is now clear evidence, from a variety of studies, that galactic bars contribute to and/or accelerate processes which quench galaxies. However, bars have a variety of strengths and pattern speeds, and previous work has suggested that slow and strong bars impact their hosts the most. In this paper, we continue to investigate the impact of bar strength and bar speed on host galaxy evolution in a sample of barred galaxies identified via classifications from Galaxy Zoo. We perform a comprehensive assessment of star-formation tracers spanning a variety of timescales, based on spatially resolved spectroscopic information from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey. Specifically, we examine the radial distributions of EW[Halpha], HdeltaA, Hbeta, and Dn4000; spectral data that trace star-formation on current, intermediate, and much longer timescales. We investigate how these star-formation tracers vary with respect to each other in diagnostic evolutionary planes for eight categories of barred galaxies (combinations of star forming or quenching; strong and weak; fast and slow). We continue to find that slow-strong bars drive the quenching of their hosts the most by triggering active star-formation throughout the barred region; however, we note some additional complexity: we observe that stronger bars boost star-formation at the bar centre while slower bars have increased star-formation along the bar. This work adds to the growing evidence that galactic bars have both global and local impacts on their host galaxies.

Residual foreground contamination in thermal Sunyaev-Zeldovich (SZ) Compton-$y$ parameter maps ($y$-maps) arises mainly from Galactic emissions -- thermal dust and synchrotron radiation -- on large angular scales, and from cosmic infrared background (CIB) anisotropies on small scales. Unlike the thermal SZ effect, Galactic foregrounds are strongly polarized. Exploiting this distinction, we introduce a hybrid Needlet Internal Linear Combination (Hybrid NILC) method that combines Planck total-intensity and polarization frequency maps in the component-separation pipeline, thereby improving the suppression of residual Galactic emission while preserving the unpolarized SZ signal by leveraging the intrinsic $TE$ and $TB$ correlations of thermal dust and synchrotron. Using Planck PR4 data, we find that the Hybrid NILC $y$-map exhibits about $40\,\%$ lower cross-correlation with the IRAS dust tracer than the standard temperature-only Planck $y$-map, indicating reduced residual Galactic contamination. Simulations further indicate that, for future high-sensitivity surveys such as LiteBIRD, the Hybrid NILC will become increasingly effective at suppressing Galactic residuals. We further address small-scale extragalactic contamination by selectively deprojecting specific moments of the CIB using a Constrained Hybrid NILC variant, achieving an improved balance between CIB suppression and noise penalty compared to previous implementations in the literature. These novel approaches -- particularly the joint use of temperature and polarization in component separation -- offer a powerful framework for disentangling polarized and unpolarized signals.

In this study we adapt a classical cosmology measurement, the volume or number density test, to a modern synthesis of observed galaxy evolution. We do this by using measured galaxy mass functions and the history of galaxy evolution through star formation and galaxy mergers, inspired by the latest results from deep extragalactic surveys. We develop a new framework using measured galaxy volume number densities as a function of redshift and volume to determine cosmological parameters, especially those which alter the volume of the Universe at a given redshift. Whilst this is a classic cosmology test proposed since at least the 1930s, it has largely been abandoned for decades due to uncertainties in galaxy evolution which make it difficult to trace galaxy populations through time. However, recent advances in our understanding of star formation and the merging history of galaxies allow us to revise this method to uncover and measure cosmological parameters, especially those which involve the nature of dark energy. We present a modified version of the volume test, called the revised evolutionary volume Tolman test, using properties of known galaxy evolution as part of the cosmological calculation. We show how this method can successfully be applied and is competitive with other major cosmological measurement methods, including those using supernova and the CMB, when the merger and star formation histories can be measured accurately to between 1 to 10 percent. This accuracy is not yet achievable, but we discuss how future missions will allow these astrophysical quantities to be known at this level. Within this measurement accuracy we can measure the dynamical properties of dark energy, including its evolution through its equation of state. We also give a fuller accounting of the future use of this new method with upcoming galaxy surveys such as Euclid and LSST/Rubin.

Recent evidence from Parker Solar Probe on the suprathermal electrons with Kappa-type velocity distributions in the outer corona has revived interest in the kinetic-based macro-modelling of the solar (SW), aiming to explain its properties. Invoked in kinetic modelling of nonequilibrium plasmas, standard Kappa distributions (SKDs) have been adjusted to the regularized Kappa distributions (RKDs) to fix the inconsistencies of SKD and develop consistent fluid modelling of space plasmas. We propose a new analysis of these properties at large heliocentric distances based on the existence of RKD electrons at the exobase. This new semi-analytic formalism is inspired by the methodology proposed initially by Meyer-Vernet and Issautier (1998), this https URL. Compared to SKDs, the results for RKDs have extended applicability, since all moments can be defined and calculated consistently for all values of the $\kappa$ parameter, even lower than the critical ones (e.g., $\kappa_c=3/2$ imposed to the second-order moment) of SKDs. However, the excess energy of the more energetic suprathermal electrons associated with low values of $\kappa \lesssim 3/2$, is regulated by the RKD-specific cutoff parameter $\alpha < 1$. The estimates for, e.g., the temperature and bulk velocity of the SW, remain at realistic values even for small $3/2 < \kappa \lesssim 2$, which would otherwise exceed specific observations. One can thus model a higher abundance of suprathermal electrons at the exobase (e.g., $\kappa \leqslant 3/2$), which is plausible for the sources of energetic events (flares and coronal mass ejections), and also in the astrospheres of stars with coronas hotter than the Sun's.

Laser frequency combs (LFCs) are a promising technology for wavelength calibration of astronomical high-resolution spectrographs requiring utmost accuracy and stability, since they directly translate the fundamental SI time standard from the radio frequency regime to optical frequencies. However, they have so far seen limited use in practice, due to their complexity, incomplete wavelength coverage, but also the challenges in the data analysis they imply. Here, we present a detailed test of a 34 GHz electro-optic modulation comb with the ESPRESSO spectrograph. Using thin-film lithum-niobate waveguides for broadening and harmonic generation, the setup provides partial coverage of the IR, visible, and near-UV spectral ranges. We focus on assessing the quality of the delivered spectra and their capability to facilitate accurate and stable wavelength calibration. We present a detailed analysis of the spectrally-diffuse background, the line width, and characterize the line-spread function over a broader width than possible with the ESPRESSO facility LFC. Comparing both combs, we find strong local discrepancies in the wavelength calibration accuracy up to 15m/s , which correlate with the echellogram structure. These do not originate from the lasers, but from misalignments in the ESPRESSO calibration unit, highlighting the strong need to make instrument fiber feeds more robust to light-injection effects. Nevertheless, we demonstrate excellent stability of the wavelength calibration, with a scatter of only 17cm/s . This, however, can only be achieved when accurately modeling the non-Gaussian line-spread function, showcasing the need for advanced data analysis techniques when dealing with LFC spectra.

(Abridged) Recently, streamers have been observed causing shocks at the outer edge of protoplanetary disks. The study of sulfur-bearing species can help us to understand the physical and chemical changes caused by infalling streamers toward their landing positions. We study the physical properties traced by SO$_2$ and SO toward the Class I protostar Per-emb 50, which is possibly related to the streamer infalling toward its disk. We present new NOEMA A-array observations as part of the large program "Protostars and Disks: Global Evolution" (PRODIGE). We analyzed the morphology of SO$_2$ and SO, and complement our interpretations with additional H_$2$CO and CO data from the same program. We compared the SO$_2$ and SO morphology with an infalling-rotating model. We applied Bayesian model selection to the brightest SO$_2$ line to disentangle the different kinematic components traced by this molecule. We used Local Thermodynamic Equilibrium (LTE) and non-LTE analyses to determine the temperature and density of the SO$_2$ emission. There are two separate peaks of SO$_2$ emission offset toward the southwest of Per-emb 50, one brighter (peak 1) at about 180 au from the protostar, and a weaker one (peak 2) at about 400 au. Peak 2 is blueshifted with respect to an infalling-rotating envelope. We propose that this peak is caused by the shock between the inner envelope and the streamer. Peak 1 is consistent with the expected envelope motion, and could thus be caused by shocks at the disk-envelope interface, but potential streamer influence cannot be neglected. Both peaks show abundance ratios consistent with a low velocity shock ($\sim 3-4$ \kms) when compared with shock models. Streamers can affect the physical and chemical structure of both disks and envelopes, suggesting that streamers can play an important role in shaping both structures in the embedded stages of star formation.

A widely accepted picture of an accretion flow in the luminous soft spectral state of X-ray binary systems is a geometrically thin disc structure much like the classic analytic solution of Shakura \& Sunyaev. Although the analytic models are troubled by instabilities and miss important aspects of physics, such as magnetic fields, they are successfully used as a framework for interpreting observational data. Here, we compare the results of general relativistic radiative magnetohydrodynamic (GRRMHD) simulations of optically thick, mildly sub-Eddington accretion on a stellar-mass black hole (the puffy disc) with established analytic and semi-analytic accretion models in the same regime. From the simulations, we find that the accretion flow is stabilised by the magnetic field, with a puffed-up, optically thick region resembling a warm corona surrounding a denser and cooler disc core. However, the stratified vertical structure of the disc significantly influences the observational picture of such a system. We analyse the inner disc structure, flow properties, effective viscosity, and inner edge position, and compare them to the predictions of standard models. We find that the simulated discs share some similarities with the models; however, they differ in several important aspects, most notably: the photosphere is geometrically thick, the inner edge is located closer to the central black hole than the analytic models assume, the surface density is significantly lower than analytically predicted, and the effective viscosity parameter is not constant but rises steeply in the innermost region.

The Sunrise balloon-borne solar observatory is equipped with a one-meter aperture optical telescope, offering a unique platform for uninterrupted seeing-free observations across ultraviolet, visible, and infrared wavelengths from altitudes higher than 33 km. For the third flight of the upgraded Sunrise observatory conducted in 2024, now called Sunrise III, a new spectro-polarimeter called the SCIP was developed for observing near-infrared wavelength ranges around 770 nm and 850 nm. These wavelength ranges contain many spectral lines, including two of the Ca II infrared triplet, K I D1 and D2 lines, and multiple Fe I lines, that are sensitive to solar magnetic fields and velocities in the photosphere and chromosphere. Polarimetric measurements are conducted using a rotating waveplate as a modulator and polarizing beam splitters in front of the cameras. The spatial and spectral resolutions are 0.21" and 2x10^5, respectively, and a polarimetric sensitivity of 0.03% (1sigma) of the continuum intensity is achieved within a 10 s integration time. To detect small polarization signals with good precision, we carefully designed the opto-mechanical system, polarization optics and modulation, control electronics, and onboard data processing. Together with the other post-focus instrumentation developed for Sunrise III, the Sunrise Ultraviolet Spectropolarimeter and Imager and the visible imaging spectro-polarimeter Tunable Magnetograph, SCIP provides novel and unique observations to understand the energy transfer and dynamical processes through the photosphere-chromosphere.

The concept of two perpendicular one-dimensional coded aperture cameras, necessitated by the imaging capability of the detector, finds its application in the design of the Wide Field Monitor (WFM). This instrument has the future goal to monitor the variable X-ray sky for transient activity. Characteristic of each camera is a fine angular resolution in one direction (typically 5 arcmin) and a coarse one in the other (5 degrees). The coarse perpendicular resolution makes the camera so-called '1.5D'. The WFM has been studied for a number of space-borne X-ray observatory concepts: LOFT, eXTP, Strobe-X, ARCO and now LEM-X. We here report on a study of two decoding algorithms for this instrument and its imaging performance. Detector responses to the X-ray sky are simulated, including the signal processing by the front-end and back-end electronics. The decoding algorithms are the iterative removal of sources (IROS), in combination with cross correlation, and the maximum likelihood method (MLM). IROS is most suited for the determination of the point source configuration of the observed sky and MLM for the optimum determination of the source fluxes. (..) the WFM is a high performance monitoring instrument with straightforward and proven technology that enables the identification of new cosmic X-ray sources, for instance X-ray novae, gamma-ray bursts and electromagnetic counterparts to gravitational wave events from merging compact objects, and the detection of unusual and interesting behavior of persistent cosmic X-ray sources, such as accretion disk state changes.

The excess abundance of highly siderophile elements (HSEs), as inferred for the terrestrial planets and the Moon, is thought to record a `late veneer' of impacts after the giant impact phase of planet formation. Estimates for total mass accretion during this period typically assume all HSEs delivered remain entrained in the mantle. Here, we present an analytical discussion of the fate of liquid metal diapirs in both a magma pond and a solid mantle, and show that metals from impactors larger than approximately 1 km will sink to Earth's core, leaving no HSE signature in the mantle. However, by considering a collisional size distribution, we show that to deliver sufficient mass in small impactors to account for Earth's HSEs, there will be an implausibly large mass delivered by larger bodies, the metallic fraction of which lost to Earth's core. There is therefore a contradiction between observed concentrations of HSEs, the geodynamics of metal entrainment, and estimates of total mass accretion during the late veneer. To resolve this paradox, and avoid such a mass accretion catastrophe, our results suggest that large impactors must contribute to observed HSE signatures. For these HSEs to be entrained in the mantle, either some mechanism(s) must efficiently disrupt impactor core material into $\leq0.01$ mm fragments, or alternatively Earth accreted a significant mass fraction of oxidised (carbonaceous chondrite-like) material during the late veneer. Estimates of total mass accretion accordingly remain unconstrained, given uncertainty in both the efficiency of impactor core fragmentation, and the chemical composition of the late veneer.

Context. In the context of galactic archaeology, the study of the Small Magellanic Cloud (SMC) is of crucial importance, as it represents a unique opportunity to study a nearby massive dwarf system. However, theoretical studies of the chemical evolution of this galaxy are strikingly lacking. Aims. In this study, we investigate the chemical enrichment of the SMC galaxy. Besides alpha and Fe-peak elements, we devote particular attention to the evolution of neutron-capture elements with different origin, namely r-process (Eu), weak s-process (Zr) and main s-process (Ba, La). Methods. We develop chemical evolution models that use as input the star formation histories obtained from colour-magnitude diagram fitting. We follow in detail the chemical feedback provided by a large variety of nucleosynthetic sources. Model predictions are compared with recent abundance measurements for the SMC. Results. The developed framework reproduces well all the observables for elements up to the Fe-peak. The abundance patterns of n-capture elements are simultaneously reproduced only by assuming an enhanced contribution from the delayed r-process at low metallicity and a top-lighter IMF relative to the reference IMF by Kroupa (2001). In this way, both the observed very high plateau in [Eu/Fe] and the rising trends in [s-process/Fe] ratios can be reproduced by the models. Conclusions. This study provides for the first time information on the evolution of several n-capture elements in a massive dwarf irregular galaxy, also providing insight on several ingredients driving galactic evolution. Moreover, this work provides a test-bed for further modelling of the SMC in the context of the numerous surveys that will target the Magellanic Clouds in the next years.

We report the discovery and characterization of two compact galaxies, Pelias and Neleus, at z ~ 0.71 and z ~ 0.75, identified in MACS J0416.1-2403 and GOODS-North. Both exhibit unusual spectral energy distributions (SEDs), with very blue rest-frame UV-optical emission and a steep rise toward near- and mid-infrared wavelengths. JWST/NIRISS and JWST/NIRSpec spectroscopy show strong rest-frame optical lines ([O III] 4959,5007 and Halpha) with extreme equivalent widths (>= 1000 Angstrom), indicating young burst-dominated populations with low metallicities (Z ~ 0.1-0.4 Zsun), low dust attenuation (Av ~ 0.2 mag), and stellar masses of Mstar ~ 10^7 Msun. Nonetheless, JWST/MIRI photometry reveals a strong mid-infrared excess that cannot be explained by stellar populations or star-formation-heated dust alone, requiring a hot-dust component most naturally associated with a deeply embedded active galactic nucleus (AGN). SED modelling yields log10(Lbol [erg/s]) ~ 43.7-44.0, implying black hole masses of log10(MBH [Msun]) ~ 5.7-6.7 under the assumption of Eddington-limited accretion. Given the very low stellar masses of the hosts, this corresponds to black-hole-to-stellar mass ratios of about 6-60%, well above the extrapolation of local scaling relations. The lack of X-ray detections suggests that the accretion may be either heavily obscured or intrinsically X-ray weak. Their SEDs also resemble those of Blue Excess Hot Dust Obscured Galaxies and show the characteristic V-shaped continuum seen in Little Red Dots, although with the inflection occurring at redder wavelengths.

High-mass stars, with their powerful winds and intense radiation fields, are fundamental in regulating galactic dynamics and evolution; however, despite their great relevance, the mechanisms involved in their formation are still not fully understood. In this context, molecular outflows, which are essential for removing angular momentum and allowing accretion onto the central object, are a crucial phenomenon for characterizing their formation. Previous studies reveal a discrepancy in the masses of outflows associated with high-mass clumps between works conducted at the clump scale ($\sim$ pc) and those at the core scale ($\sim$ subpc). This suggests that the high-mass outflow activity observed at the clump scale might be the result of the contribution from several lower-mass outflows linked to individual molecular cores. This work presents a study of the molecular gas toward a high-mass clump associated with an Extended Green Object (EGO). EGOs are indicators of jets associated with high-mass protostars. Employing high angular resolution data from the Atacama Large Millimeter/submillimeter Array (ALMA), the presence of several hot cores with outflow activity was observed in the source. A characterization of the outflows at the core scale is presented within the context of the physical parameters of the molecular clumps.

There is increasing evidence for multiple binary black hole~(BBH) subpopulations in the cumulative gravitational wave catalog by the LIGO-Virgo-KAGRA Collaboration. The astrophysical interpretation of this complex underlying population is subject to theoretical uncertainties in treatments of binary stellar evolution, core collapse, and host environments. In this \textit{Letter}, using parametrized mixture models, we show that the BBH detection sample comprises three astrophysical subpopulations that are likely dominated by specific formation channels. In particular, we show that the $10M_{\odot}$ peak and the $35M_{\odot}$ feature in the BBH mass spectrum correspond to distinct mass-ratio, spin alignment, spin precession, and redshift evolution properties. We show that mass-based transitions reported in the distribution of BBH parameters naturally emerge from our inferred distributions without explicit modeling. Our results are consistent with the current observed population arising from specific relative abundances of isolated binary evolution, dynamical formation in globular clusters, and higher-generation BBH mergers. Under this interpretation, we constrain the relative underlying fraction of these channels to be $79.0^{+11.5}_{-10.9}\%$, $14.5^{+11.6}_{-8.0}\%$, and, $2.5^{+5.5}_{-1.8}\%$, respectively, and find these relative fractions to be evolving over cosmic time with more than $1\sigma$ confidence. Our interpretation relies on simple theoretical predictions that are mostly robust against uncertainties in BBH formation, with more definite conclusions expected in the near future.

Precise and accurate ages for asteroidal crusts are fundamental for reconstructing the timeline of magmatic, metamorphic, and impact events in the early Solar System. Zirconolite (CaZrTi2O7) is an accessory mineral found in a wide range of crustal rocks on both the Earth and Moon, and has proven to be a potentially useful U Pb chronometer. However, this mineral is rare in asteroidal meteorites, and its use for early Solar System chronology has been limited. We present the in situ occurrence, U Pb chronology, and chemistry of zirconolite in the andesitic meteorite Erg Chech 002, which represents a sample of the oldest known asteroidal crust. The zirconolite occurs as needle- and fiber-shaped, stubby crystals, with widths of 3 micrometers and lengths of up to 30 micrometers. Electron and ion microprobe analyses yielded concordant U Pb data with a weighted mean 207Pb 206Pb age of 4557.9 4.3 Ma 2sigma, rendering it the Solar System's oldest known zirconolite. Yet, this age is distinctly younger than reported high-precision 207Pb 206Pb ages varying from 4565.6 to 4566.2 Ma, which were obtained by acid leaching of pyroxene and whole rock samples of the meteorite. From its mineralogical and REE (U+Th) (Nb+Ta) characteristics, we argue that the zirconolite age represents the timing of a shock metamorphism of the parent asteroid's crust. Our results suggest that 207Pb 206Pb dating for acid-leached samples can be affected by including even a tiny amount of metamorphic zirconolite, calling for caution in interpreting the high-precision 207Pb 206Pb age data. On the basis of thermodynamic and geochemical considerations, we infer further occurrences of zirconolite in alkali-silica-rich asteroidal rocks that rapidly cooled from high temperatures.

Interest in the topic of geodetic co-location in space and space ties has recently intensified within the geodetic community, particularly following the approval of the European Space Agency's (ESA) Genesis mission. From the perspective of Very Long Baseline Interferometry (VLBI), observations of Earth-orbiting satellites are not standard practice yet. To enable VLBI support for future colocation satellite missions, such observations must be integrated into the VLBI processing chain. In this study, we present comprehensive VLBI observations of Galileo navigation satellites conducted with the Australian AuScope VLBI array. Using the 12-m antennas in Hobart, Katherine and Yarragadee equipped with VLBI Global Observing System (VGOS) instrumentation, Galileo E1 and E6 signals were observed in test experiments and a series of four full-scale 24-hour observing sessions. We present the estimation of VLBI station coordinates from observations to navigation satellites, thereby demonstrating, for the first time, inter-technique ties between the VLBI and Global Navigation Satellite System (GNSS) frame. We describe the processing strategy, including correlation, fringe fitting, precision assessment and satellite tracking approach. Delay observables achieve precisions of a few picoseconds in the E1 band and several tens of picoseconds in the E6 band for 1-s integration times. However, unmodelled signals on the order of several hundred picoseconds are found in the residual delays. Estimated station coordinates agree with a priori values at the metre level, while baseline lengths agree at the sub-metre level. These results demonstrate the feasibility of large-scale VLBI observations to GNSS satellites and provide critical groundwork for future co-location satellite missions such as Genesis.

Within the general framework of $f(R)$ gravity, we introduce a function of the electromagnetic curvature invariant $f(\mathbb{F})$ that couples minimally to gravitation to ensure a consistent treatment of curvature functions in these theories. We show that one of the solutions leads to field equations that are a generalization of the Klein-Gordon equation while the other leads to a typically non-linear massless solution. Focusing on flat spacetime, our formalism recovers the Plebanski family of models and Bopp-Podolsky electrodynamics as specific limits. These extensions may have phenomenological consequences in extreme environments, such as the early universe or near charged compact objects, where deviations from classical electrodynamics might be probed.

$Q$-stars are a class of boson stars arising in scalar-field theories with interacting potentials, minimally coupled to gravity. We show that, in certain regions of parameter space, the angular velocity of stable timelike circular geodesics around $Q$-stars can attain a maximum at a nonzero radius. Notably, this behaviour may occur for stable configurations. This feature has been argued to produce effective shadows, but so far it has only been investigated for unstable solutions. We test this possibility by performing general relativistic magnetohydrodynamic evolutions for a representative stable $Q$-star model. A low-density, low-luminosity central region is indeed observed to form and persist -- at least until the evolution becomes affected by numerical viscosity. As a proof of principle, this suggests that families of stable bosonic stars can act as black hole mimickers. Moreover, for the model at hand, a heuristic analysis shows that the effective shadow has a comparable size to that of a Schwarzschild black hole with the same mass. Importantly, this mechanism for generating an effective shadow does not rely on the object being ultracompact, or an ad hoc chosen accretion disk.

Motivated by the DAMA/LIBRA annual modulation signal, the dark matter community has invested heavily in ultra-clean underground NaI detectors to search for light WIMPs. We point out a new target of opportunity for these detectors -- axions produced by the carbon-burning stars within our galaxy. These stars synthesize large quantities of $^{23}$Na, keeping it at temperatures $\sim 10^9$K for periods up to tens of thousands of years. Under these conditions, $^{23}$Na radiates 440 keV axions through repeated photo-excitation and axio-deexcitation of its first excited state. Upon reaching a NaI detector, the process is reversed: the axion is resonantly absorbed, producing a 440 keV deexcitation photon. NaI thus serves as both $\gamma$ source and $\gamma$ detector. We find that existing NaI detectors can probe axion-nucleon couplings $|g_{aNN}^\mathrm{eff~^{23}Na}| \approx g_{app} \sim 10^{-6}$--$10^{-2}$, including QCD axions with $m_a \gtrsim 10$ eV. While there are several astrophysical constraints on axions with these couplings, our re-examination of these bounds shows that substantial gaps remain, providing strong motivation for the proposed searches.

The Galactic Center Excess (GCE) is a compelling signature of dark matter annihilation, but its spectral morphology is difficult to reconcile with the traditional paradigm of a single particle species. In this work, we perform a systematic investigation of multi-component dark matter sectors, exploring scenarios with two ($N=2$) and three ($N=3$) distinct particle species while considering both exclusive and mixed annihilation channels. Using the Akaike Information Criterion (AIC) to rigorously penalize model complexity, we find that the GCE data statistically favors an $N=2$ scenario where each dark matter component annihilates exclusively into a single final state. Our results reveal that the preferred solutions naturally follow a light-plus-heavy mass hierarchy, and that specific final states such as $t\bar{t}$, $ZZ$, and $hh$, which are individually unable to explain the excess are effectively ``resurrected'' by the improved morphological fit provided by the multi-component framework. Furthermore, we show that these scenarios may mitigate the tension with current constraints, reaching compatibility within existing uncertainties. Our results suggest that the GCE may be the first evidence of a diverse dark sector, favoring a multi-scale solution over the minimal WIMP paradigm.

Upcoming astronomical surveys produce imagery that spans many orders of magnitude in spatial scale, requiring scientists to reason fluidly between global structure and local detail. Data from the Vera C. Rubin Observatory exemplifies this challenge, as traditional desktop-based workflows often rely on discrete views or static cutouts that fragment context during exploration. This paper presents a design-oriented framework for scale-aware navigation of astronomical survey imagery in high-resolution immersive display environments. We illustrate these principles through representative usage scenarios using Vera Rubin Observatory and Milky Way survey imagery deployed in room-scale immersive environments, including tiled high-resolution displays and curved immersive systems. Our goal is to contribute design insights that inform the development of immersive interaction paradigms for exploratory analysis of extreme-scale scientific imagery.

Quasi-topological theories of gravity are known to resolve black-hole singularities. We investigate whether the same mechanism can remove cosmological singularities. Focusing on non-polynomial curvature quasi-topological gravities in $d=4$ dimensions, we find three generic scenarios with the correct infrared limit but without a Big-Bang singularity, for universes filled with pure radiation or other standard matter. The first scenario yields a universe emerging from a de Sitter phase, a case for which the curvature invariants remain finite but the matter density diverges, albeit only at infinite affine distance. The second one corresponds to a bouncing universe, which requires a multi-valued Lagrangian. The third possibility is an asymptotically Minkowski origin, reminiscent of an eternally loitering universe. The matter energy density for this solution is non-singular even at infinite affine distance and does not enter a super-Planckian regime, but is instead approximately constant for the past eternity.

Collisionless shocks are fundamental accelerators of energetic particles; yet, the observations of nonlinear foreshock structures, which are essential in acceleration processes, differ significantly between Interplanetary (IP) shocks and planetary bow shocks. We present a direct comparison of two high-Mach-number, quasi-parallel shocks: an IP shock observed by Solar Orbiter and the Earth's bow shock measured by the Magnetospheric Multiscale (MMS) mission during the 2024-2025 ``string-of-pearls'' campaign. We show that Foreshock Compressive Structures (FCSs) initiate upstream of both shocks at similar normalized distances ($\lesssim$50 ion inertial lengths, $d_i$) when the suprathermal ($>10$ keV) ion density exceeds $\sim$1\% of the background. However, the IP shock lacks the fully evolved, high-amplitude Short Large Amplitude Magnetic Structures (SLAMS) characteristic of the terrestrial foreshock. We demonstrate that the ``growth zone'' capable of sustaining these structures is spatially limited ($\sim$135 $d_i$), which, due to the high speed of the propagating IP shock, corresponds to a brief observational window of $<10$ s. Beyond this observational constraint, we suggest an additional physical mechanism that can inhibit foreshock maturity at IP shocks. The lack of global curvature prevents the lateral supply (``cross-talk'') of energetic ions from different shock regions. These findings suggest that while the fundamental physics of FCS initiation is unified across collisionless shocks, the achievement of full nonlinearity can be regulated by the unique shock geometry and upstream properties, while ultimately remaining observationally challenging to identify.