Earth and Planetary Astrophysics
Scaling law for the diffusion coefficient in vibration-driven crater relaxation
Hayato Narita and Hiroaki Katsuragi
Impact craters relax over long timescales, and this process is commonly described by a
diffusion model. The
diffusion coefficient determines the relaxation rate, and it has been estimated from observed crater shapes. This coefficient, however, represents the combined effect of several physical mechanisms. Its physical basis has not been revealed yet. In this study, we isolate the contribution of seismic vibration in a controlled experiment. Using a quasi-two-dimensional setup, we first confirm that a linear
diffusion equation reproduces the crater relaxation. We then measure the
diffusion coefficient and obtain the scaling form through systematic experiments. We find that the
diffusion coefficient is proportional to the crater diameter. This dependence is not expected for simple
diffusion. We interpret this dependence as arising because the thickness of the vibro-fluidized granular layer scales with the crater depth. This scaling relation is the main result of this study. We then apply it to the Moon with a parameterized model of impact-driven seismic spreading in the regolith layer. Integrating over the impact flux yields a macroscopic coefficient nearly proportional to crater diameter for shallow-layer-like spreading. Its magnitude depends on uncertain model parameters but is consistent with observations for plausible values. These results indicate that vibration is a physically plausible contributor to crater relaxation on the Moon.
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Instrumentation and Methods for Astrophysics · Cross-listed from physics.hist-ph
The Surviving Fragment of the Zij-i Malikshahi: A Preliminary Edition, Translation, and Study of the 100-Star Catalogue in BnF Arabe 5968
Rizoi Bakhromzod
The astronomical programme sponsored by the Saljuq Sultan Malikshah I in the late eleventh century occupies an important place in the history of Islamic astronomy. Umar Khayyam was a principal participant in this programme, which produced the Jalali or Maliki calendar and appears also to have resulted in a broader set of astronomical tables known as the Zij-i Malikshahi. A 100-
star catalogue traditionally associated with these tables survives in the anonymous Arabic compendium Dustur al-munajjimin, preserved in the unique manuscript BnF Arabe 5968. This study distinguishes the catalogue from the Jalali calendar and from the lost or unidentified complete Zij-i Malikshahi, reconstructs its historical and manuscript context, and examines the provenance of BnF Arabe 5968. It presents a complete transcription of the catalogue from fols. 224r-225r and a new English translation made directly from the Arabic text, with B. A. Rosenfeld's 1961 Russian translation used as a control. The collation identifies several divergences, including a substantive correction to the longitude of entry 8, and clarifies the planetary temperament abbreviations. Rosenfeld and A. P. Yushkevich observed that 96 of the 100 stellar longitudes correspond to Ptolemaic values increased by about 14 degrees 26 minutes, while 87 latitudes agree with Ptolemy. These correspondences suggest systematic updating of inherited Ptolemaic data rather than 100 wholly independent observations, illustrating the combined roles of observation, computation, transmission, and adaptation in medieval Islamic astronomy.
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High Energy Astrophysical Phenomena
G(2) Glueball Boson Stars as Restricted Kerr Mimickers in the Thomas–Fermi Limit
Nicolò Masi
We investigate whether horizonless compact
stars made of dark glueball matter from a broken exceptional $G(2)$ gauge sector can reproduce selected Kerr observables within a Thomas–Fermi effective-fluid description. We introduce GC9, a scale-separated $G(2)$-inspired positive nonic-density closure whose high-density stiffness, bag-free surface and Q-ball safety make it a useful compact-
star benchmark. After Thomas–Fermi rescaling, reduced stellar observables are independent of the microscopic glueball mass $m_G$, while the collective stiffness $\Lambda_T$ fixes the dimensional mass and radius. Solving the TOV, Hinderer and Hartle–Thorne systems, we obtain a stable maximum-mass compactness $C=0.3247$, tidal deformability $\Lambda=4.37$, $\bar I C^{3/2}=0.947$, and slow-rotation quadrupole $\bar Q=1.522$. At $j=0.328$, the same-order ISCO shift is $1.24\%$. The stable endpoint has no light ring, but its exterior Regge–Wheeler barrier supports a genuine static axial mode, $M\omega=0.463846-0.098881i$, with a damping time about ten percent shorter than Schwarzschild and a real frequency $24.1\%$ higher. A polarization-balanced vector realization has the same isotropic bulk EOS; moderate residual anisotropy changes static and first-order observables only at the few-percent level, while the full coupled vector spectrum remains open. Cowling calculations identify matter-supported quadrupolar modes. The scalar-burst, seeded-collapse and cosmological sections are phenomenological: a fixed $\Lambda_T$ gives a compact Kerr-comparison branch only near its own maximum mass, so the multi-sector scenario assumes distinct constant-$\Lambda_T$ branches from the keV supermassive sector to the PeV asteroid-mass sector. GC9 therefore defines a falsifiable restricted Kerr-mimicry framework for gravitational-wave, horizon-scale and compact-dark-matter tests.
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Earth and Planetary Astrophysics · Cross-listed from physics.flu-dyn
Fluxes through a uniform double-diffusive staircase at low Prandtl number
Arstanbek Tulekeyev and Pascale Garaud
Double-diffusive convection in the diffusive regime is often observed to be in a long-lived layered state, well-known in the Arctic ocean and in volcanic lakes, and thought to exist in the interiors of giant
planets. The density profile resembles a `staircase', with stacks of convective layers of uniform density separated by strongly stratified interfaces. The governing parameters are the Prandtl number $\mathrm{Pr}$, diffusivity ratio $\tau$, density ratio $R_\rho$, and Rayleigh number $\mathrm{Ra}$. In this work, we perform direct numerical simulations in triply periodic domains to systematically investigate the properties of statistically stationary double-diffusive staircases with $\tau \le \mathrm{Pr} \ll 1$. We demonstrate that they can exist for significantly larger density ratios than previously reported, and propose a new criterion for the existence of long-lived layered states. Notably, this criterion depends weakly on $\mathrm{Ra}$. In all simulations, we measure the total fluxes of density $F^{\mathrm{tot}}_\rho$, temperature $F^{\mathrm{tot}}_T$ and composition $F^{\mathrm{tot}}_C$, and the flux ratio $\gamma =F^{\mathrm{tot}}_C/F^{\mathrm{tot}}_T$. We confirm that $\gamma$ is approximately constant for moderate to large $R_\rho$ but also depends weakly on $\mathrm{Ra}$. We show that the Nusselt numbers for composition and temperature scale as $\mathrm{Ra}^{1/3}$ in this limit, which notably differs from the $(\mathrm{RaPr})^{1/3}$ scaling previously found at lower $R_\rho$. We propose a new model for these findings that is based on the rise and turbulent mixing of density anomalies that form at the edges of the interfaces. The model explains the existing low $\mathrm{Pr}$ data with reasonable accuracy.
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Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Direct and Indirect searches for DM-electron interactions in sub-GeV DM models
Marco Cirelli, Arpan Kar, Antoine Letessier-Selvon et al. (+1 more)
We analyze the complementarity between direct detection (DD) and indirect detection (ID) searches of sub-GeV dark matter (DM) in the context of two realistic models: the vector-portal (dark
photon) and scalar-portal (
higgs-portal) models. For DD we focus on the latest constraints on the DM-electron scattering from the present DAMIC-M experiment as well as its future projection. For ID we consider several existing X-rays/gamma-rays and
cosmic-ray ($e^\pm$) observations as well as the upcoming MeV
telescope COSI to obtain the corresponding bounds and projections on the DM annihilation rate, which are then translated in terms of the DM-electron scattering cross-section and compared with the DD bounds/projections. We properly take into account astrophysical and galactic propagation uncertainties. We find that the complementarity between DAMIC-M and ID works best for the vector-portal model, especially for the case where the vector mediator is heavier than the DM particle: in this case, the present DAMIC-M bound becomes comparable to (or better than, for some astrophysical configurations) the combined ID limit for $3\,{\rm MeV} \lesssim m_{\rm DM} \lesssim 20\,{\rm MeV}$. For other cases and mass ranges, the ID is in general more constraining and can also, for some mass ranges, constrain the parameter space below the
neutrino floor, which is inaccessible to DD experiments.
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All authors Marco Cirelli, Arpan Kar, Antoine Letessier-Selvon, Harrys Lumengo-Kidimbu
Astrophysics of Galaxies
A radio continuum view of Stephan's Quintet: age, dynamics and origin of the shock
K. Rajpurohit, E. O'Sullivan, G. Schellenberger et al. (+10 more)
We present a detailed, multi-band
radio continuum study of the compact
galaxy group Stephan's Quintet (HCG 92). We use a combination of new (MeerKAT, uGMRT) and archival (LOFAR, VLA) observations covering the $\rm 120\,MHz{-}8\,GHz$ frequency range to examine the
radio properties of the group, focusing on the famous
radio ridge and surrounding diffuse emission. We find filamentary substructure and branching in the southern half of the ridge, confirm an extension of the ridge to the northwest, and identify for the first time a
radio counterpart to the gas bridge linking the ridge and NGC 7319. The northern ridge, northwest extension and diffuse emission have relatively steep, curved spectra, with a high-frequency spectral index gradient running north-south along the ridge. We show that the ridge emission primarily arises from a single physical mechanism, probably strong ($\mathcal{M}\simeq 40-100$) shocks in cold gas, caused by the $\rm \sim850-1000\,kms^{-1}$ collision between NGC 7318B and tidal gas filaments produced by past
galaxy interactions. Synchrotron spectral age estimates suggest the collision began at the north end of the ridge $\rm \sim20\,Myr$ ago, and finished only $\rm \sim5-6\,Myr$ ago in the south, with the southern end of the shocked ridge likely still within or close to the disk of NGC 7318B. Based on this age gradient, we find that the angle between the intruder
galaxy's motion and the tidal filaments was probably only about 15 degrees, and combining this with the lack of a spectral index gradient in the diffuse
radio emission suggests that NGC 7318B's direction of motion is probably close to the line of sight.
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All authors K. Rajpurohit, E. O'Sullivan, G. Schellenberger, A. Botteon, R. J. van Weeren, U. Lisenfeld, J. M. Vrtilek, L. P. David, S. Giacintucci, W. Forman, C. Jones, C. K. Xu, A. Togi
Astrophysics of Galaxies
Systematic uncertainties on DESI Tully-Fisher distances constrained with Integral Field Spectroscopy
Utsav Siwakoti, Lluis Galbany, Kelly A. Douglass et al. (+40 more)
The Tully–Fisher (TF) relation is an empirical tool for estimating distances to spiral
galaxies. The Dark Energy Spectroscopic Instrument (DESI) Peculiar Velocity (PV) Survey uses `tractor' photometric position angles to place fibers along the
galaxy's semi-major axis and infer maximum rotational velocities for $\approx$ 53,000 spirals. Systematic errors arise if the photometric PA differs from the kinematic PA from velocity fields. We quantify systematic uncertainties in DESI-TF distance estimates from photometric PAs and assess the impact of photometric–kinematic PA misalignments. We analyze 215 nearby
galaxies from the PISCO and AMUSING surveys, estimating maximum rotational velocities at $0.4\,R_{26}$ for consistency with DESI-PV. Kinematic parameters are derived using `PaFit' from `Cappellari Software'. Global photometric parameters rely on Siena
Galaxy Atlas SGA-2020 `tractor' data, with `HostPhot' as an alternative approach. Approximately $28\%$ of our sample exhibit photometric–kinematic PA misalignments $>10^\circ$. The median bias in distance is $\approx +1.98\,\mathrm{Mpc}$ with a skewed residual distribution of outliers. The overall distance standard deviation is $19.35\,\mathrm{Mpc}$, with misaligned
galaxies showing twice the dispersion of aligned ones. The Mean Percentage Error is $2.8\% \pm 1.96$ (SE). High
galaxy-to-
galaxy scatter appears in DESI-TF distances, particularly for misaligned systems. Because DESI-TF targets lack kinematic PA measurements, we recommend a global fractional uncertainty of $\approx 3.5\%$. When kinematic information is available, aligned
galaxies with offsets $<10^\circ$ are consistent with $\approx 1\%$ uncertainty, while strongly misaligned or incomplete systems warrant an upper threshold of $\approx 10\%$.
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All authors Utsav Siwakoti, Lluis Galbany, Kelly A. Douglass, Ariel J. Amsellem, Benjamin A. Weaver, J. N. Aguilar, S. Ahlen, D. Bianchi, D. Brooks, T. Claybaugh, A. de la Macorra, P. Doel, S. Ferraro, J. E. Forero-Romero, E. Gaztanaga, S. Gontcho A Gontcho, G. Gutierrez, C. Hahn, K. Honscheid, C. Howlett, D. Huterer, R. Joyce, S. Juneau, R. Kehoe, T. Kisner, A. Kremin, M. Landriau, L. Le Guillou, M. Manera, R. Miquel, J. Moustakas, S. Nadathur, W. J. Percival, I. Perez-Rafols, F. Prada, G. Rossi, E. Sanchez, D. Schlegel, R. Sharples, J. H. Silber, D. Sprayberry, G. Tarle, H. Zou
Solar and Stellar Astrophysics
Fine-scale flare structures and their energetic implications from short-exposure extreme-ultraviolet imaging
Laura A. Hayes, Hannah Collier, Säm Krucker et al. (+5 more)
To capture the brightest and most rapidly evolving phases of solar
flares, the Major
Flare Solar Orbiter Observing Plan employed a dedicated short-exposure mode for the High Resolution Imager at 174 Angstrom (HRIEUV) of the Extreme Ultraviolet Imager. We investigate the spatial and temporal organisation of compact emission in the 19 March 2024 M2.1
flare using high-cadence, short-exposure HRIEUV observations. We combine these 0.04 s observations with hard X-ray timing, imaging, and spectroscopy from the Spectrometer
Telescope for Imaging X-rays (STIX). We characterise impulsive ribbon kernels and later loop strands, and compare footpoint areas measured with HRIEUV, the Atmospheric Imaging Assembly, and STIX to constrain the local energy flux carried by
flare-accelerated electrons. The short-exposure observations reveal compact emission largely obscured by saturation in normal-exposure EUV imaging. The integrated HRIEUV emission evolves co-temporally with the STIX 22-45 keV emission, with no lag discernible beyond the 2 s sampling. The ribbons comprise repeatedly activated kernels with characteristic separations of approximately 1.4-1.7 Mm, while the developing arcade shows a similar strand separation of approximately 1.3 Mm. Kernel and strand widths of approximately 0.4-0.5 Mm lie close to the instrumental resolution limit. The compact HRIEUV footpoint areas are approximately an order of magnitude smaller than those inferred from AIA or STIX, implying nominal local non-thermal energy fluxes on the order of 10^11 erg cm^-2 s^-1 at the hard X-ray peaks. These results reveal a characteristic 1-2 Mm spatial organisation of the
flare emission and demonstrate the value of
flare-optimised EUV imaging for future solar
flare observations.
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All authors Laura A. Hayes, Hannah Collier, Säm Krucker, Daniel Ryan, David Berghmans, Emil Kraaikamp, Muriel Stiefel, Andrew Inglis
Solar and Stellar Astrophysics
Numerical modelling of recombination-driven stellar winds
Bestin James and Jiří Krtička
Low-temperature
stars have a significant population of neutral hydrogen increasing with height in their atmospheres. This suggests eventual recombination as we move away from their deep photospheric layers. Recombination can potentially drive stellar winds, particularly in cool and evolved
stars. We aim to verify the possibility of stellar winds driven by recombination. We also aim to constitute an initial model for this type wind driving. We examine the possibility of recombination-driven outflows across the HR diagram by comparing the gravitational potential energy per atom to the hydrogen ionization energy. Then we start from a simple analytical model with the addition of an extra heating term to the gas in the Parker wind model. We model the heating term, analogous to the heat released by recombination, and examine how it can drive an outflow. We implement the model in the code CASTRO and check the hydrodynamic stability of the solution. The added heating drives a steady transonic outflow in our models, when tested with the parameters of an AGB
star. The heating function affects the solution and the location of the sonic point depends on the location of the heating function itself. Even though the derived hydrodynamic equations are independent of the density, we determine the processes that set the mass-loss rate. By comparing the heating from collisional recombination and cooling due to radiative recombination, we show that relatively high densities are required to release the recombination energy as heat, implying mass-loss rates of the order of 0.1 solar mass per year. Our comparison of energies across the HR diagram suggests a possibility of recombination-driven winds in evolved red giants and AGB
stars. The main deciding factor for wind launching is the radial distribution of heat released by recombination in a
star's atmosphere. This can in turn affect the mass-loss rate.
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Solar and Stellar Astrophysics
Path to Black Hole Astrometric Microlensing from 10-Year KMTNet Database
Andrew Gould
I present a Fisher analysis of the astrometric signature of black holes (BHs) that may lie in the 10-year KMTNet microlensing database, motivated by the recent success of the pilot study by Segev et al. (2026), which reduced the scatter at $I=18$ to $\sigma\sim 10\,$mas. Seeing-limited ground-based observations still suffer from a great deal of systematics, but under the assumption that these systematics can be controlled, I find that with this nominal precision, the Einstein radius can be measured with errors $\sigma(\theta_{\rm E})\sim 0.5\,$mas in the most intensively monitored fields ($\sim 12\,$deg$^2$), and hence to twice that value in an additional $\sim 28\,$deg$^2$ area. This precision hardly depends on whether the peak of the event is during the observing season or not, as long as the impact parameter is within the broad range that is accessible to photometric recognition of the event, i.e., $u_0\lesssim 1.5$. However, longer events do have somewhat better precision. The analysis presented here ignores blending, but this is a good first approximation for most sources $I\lesssim 18$, which lie near or on the giant branch. I outline a practical program, combining photometric and astrometric searches, aimed at identifying isolated BHs in the KMTNet database and measuring their masses and distances.
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Solar and Stellar Astrophysics
Diversity of stripped-envelope supernova light curves from interaction with binary-driven circumstellar material
Dandan Wei, Fabian R. N. Schneider, Philipp Podsiadlowski et al. (+2 more)
A growing number of core-collapse
supernovae (CCSNe) exhibit diverse light-curve morphologies that indicate strong interaction with dense, pre-existing circumstellar material (CSM). Understanding the physical origin of such CSM is essential for exploring the late-stage
evolution of SN progenitors. Non-conservative mass transfer during binary interactions provides a promising channel for producing dense CSM before core collapse. Using the stellar
evolution code MESA, we simulate post-common-envelope binaries that give rise to ultra-stripped progenitors and self-consistently construct the CSM from mass loss during binary
evolution. We further analytically predict the resulting bolometric and
radio light curves by following the shock dynamics of SN ejecta interacting with the CSM. We find that surface-radius variations in the ultra-stripped progenitors trigger multiple episodes of mass transfer and produce diverse CSM density profiles, including detached shells and multi-peaked structures. Interaction with such CSM gives rise to non-monotonic, multi-peaked optical and
radio light curves that qualitatively resemble features observed in some stripped-envelope SNe. Long-term multi-wavelength monitoring of stripped-envelope SN candidates, particularly at late times, will be crucial for probing structured CSM and constraining the mass-loss history of stripped progenitors. Our results suggest that SN-CSM interaction in binaries hosting ultra-stripped progenitors provides a possible channel for producing diverse light-curve morphologies, highlighting a potential connection between the pre-SN
evolution of massive binary
stars and the diversity of their explosive transients.
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All authors Dandan Wei, Fabian R. N. Schneider, Philipp Podsiadlowski, Takashi J. Moriya, Eva Laplace
Instrumentation and Methods for Astrophysics
Microscopy assessment of two multiple-transient candidates
Jun Yang and Beatriz Villarroel
We present a microscopy-based assessment of two representative cases of multiple-transient candidates identified on historical photographic plates: the nine-transient event of 12 April 1950 (XE325) and the triple-transient event of 19 July 1952 (XE186). These events consist of spatially clustered, point-like sources detected within single long-exposure plates, lacking the streaks expected from moving objects and therefore suggestive of short-duration flashes. We analyse microscopy images of the original glass-plate material together with an independent copy plate and archival metadata, and we register these images against the published survey digitizations so that individual catalogued sources can be located. In both cases the candidates appear slightly sharper and more compact than typical stellar point spread functions, qualitatively consistent with sub-second to few-second emission during exposures of $\sim 50$~min, and they are reproducible across different representations of the same field, which disfavours a digitization-artifact origin. However, microscopy of individual point-like features cannot by itself separate a short-duration flash from an intrinsic emulsion defect, because the two scenarios produce qualitatively similar signatures at the single-source level. We also show that the multi-observatory parallax test, while powerful in principle, is not feasible for these two specific events with presently available material, owing to the absence of a simultaneous second-site plate reaching comparable depth. We conclude that resolving the nature of these events requires population-level statistics and, where future observations allow, purpose-built multi-station imaging. This work provides a proof-of-concept framework for combining microscopy with archival analysis in the study of historical transient phenomena.
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Cosmology and Nongalactic Astrophysics
Cross-simulator transfer with foundation model summaries: Towards robust SKA-era reionization inference
Yannic Pietschke, Caroline Heneka, Ayodele Ore et al. (+1 more)
Simulation-based inference (SBI) for parameter estimation is vulnerable to model misspecification: neural summaries and density
estimators trained on a specific forward model typically fail when applied to data drawn from another model, or from real observations, and no training simulator can capture the full observational pipeline of a real measurement exactly. We show that a self-supervised
Vision Transformer (ViT), pretrained label-free on a fast approximate simulator, produces transferable data summaries that generalize across simulators. Without retraining, it can be reused as a frozen encoder to infer astrophysical parameters from a completely different simulator that resolves the radiative transfer explicitly, on which it has never seen either data or parameters. As a concrete use case in 21cm cosmology, SKATR, a ViT pretrained with a Joint
Embedding Predictive Architecture (JEPA), serves as a foundation model for reionization inference from upcoming SKA measurements: SKATR is pretrained once on 67k low-cost, noiseless semi-numerical 21cmFAST lightcones, then frozen and applied to hydrodynamical Loreli II lightcones, where a lightweight conditional flow matching head infers five astrophysical parameters; the encoder is never shown Loreli data, its parameters, or any noise. In our comparison, SKATR yields the most precise and best-calibrated posteriors across all five parameters, matching the accuracy of the fully-supervised in-domain baseline while requiring 2.6x fewer radiative-transfer simulations. Under realistic SKA AA* noise, only SKATR remains simultaneously accurate, informative, and calibrated, outperforming even a supervised baseline retrained from scratch on noisy data. Self-supervised pretraining on computationally efficient semi-numerical simulations is therefore a viable route to calibrated, simulator- and noise-agnostic reionization inference for the SKA-era.
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All authors Yannic Pietschke, Caroline Heneka, Ayodele Ore, Romain Meriot
Astrophysics of Galaxies
COSMOS-Web: From early star-formation enhancement to late suppression in galaxy groups
R. C. Arango-Toro, C. Laigle, J. Lewis et al. (+29 more)
Galaxy groups trace dense environments where interactions, gas removal, and reduced
accretion may drive quenching. Common diagnostics trace
star formation over short timescales ($\lesssim100$ Myr); time-resolved
star formation histories (SFHs) separate recent changes from longer-term
evolution at fixed mass and
redshift. Using COSMOS-Web data, we test how group environment correlates with
star-formation activity and its
evolution with
cosmic time and group-centric distance, contrasting high-richness groups with excluded field
galaxies. We combine COSMOS2025/COSMOS-Web stellar masses and non-parametric SFHs with group detections and memberships from AMICO (Adaptive Matched Identifier of Clustered Objects), comparing stacked SFHs of matched group and field
galaxies and measuring how the SFH offset evolves with group-centric distance for the richest groups. Massive
galaxies ($\log(M_\star/M_\odot)>10.5$) show the largest offsets but are already quenched in both environments. For lower masses ($8.1<\log(M_\star/M_\odot)<10.5$), suppression is clearest at $z<1.5$ (deficit up to 0.8 dex), while at $z>1.5$ SFHs show weak suppression or occasional enhancement. The radial signal evolves similarly: quenching is broad at low $z$, the inner-outer contrast sharpens at $z\gtrsim1$, and any ordering at $z\gtrsim2$ is tentative given growing uncertainties in the AMICO centroids. These results suggest an evolving picture: groups are more mixed at early epochs, with both suppressed and occasionally elevated SFHs, partly reflecting high-$z$ uncertainties, while suppression dominates from $z\lesssim1.5$, most clearly for low-to-intermediate-mass
galaxies. Inner-region
galaxies likely spend more time in the group potential, undergo more passages through dense intra-group gas, and accrete less pristine cold gas, making quenching progressively clearer with
cosmic time.
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All authors R. C. Arango-Toro, C. Laigle, J. Lewis, M. Joly, G. Toni, C. M. Casey, J. S. Kartaltepe, O. Ilbert, M. Shuntov, H. B. Akins, L. Paquereau, Y. Dubois, M. Franco, G. A. Mamon, G. Aufort, A. L. Faisst, Z. Ghaffari, G. Gozaliasl, H. Hatamnia, M. Hirschmann, M. Huertas-Company, A. M. Koekemoer, R. Laishram, D. Le Borgne, G. Leroy, H. J. McCracken, L. Moscardini, A. Nuñez-Castiñeyra, J. R. Rhee, R. M. Samir, M. Trebitsch, L. Tresse
Cosmology and Nongalactic Astrophysics
HOLISMOKES – XVIII. Cosmology with strongly lensed type II supernovae: Effects of instrumental setups on $H_0$
J. Grupa, S. Taubenberger, S. H. Suyu et al. (+3 more)
The upcoming Rubin Observatory and subsequent follow-up observations should improve the determination of the Hubble constant ($H_0$) via time-delay cosmography of strongly lensed type II
supernovae (LSNe II), by enabling the detection of many more such events. In our previous work, we developed a method for determining the
supernova (SN) phase from spectral absorption features. Because obtaining spectra of faint targets such as distant SN II is expensive, we examined how low-resolution spectra influence the precision of time-delay
retrieval, and consequently the precision on $H_0$. We considered spectral resolutions $R = \frac{\lambda}{\Delta \lambda}$ between 100 and 250, and we investigated three signal-to-noise ratio ($S/N$) values of 10, 15, and 20, for each resolution. Furthermore, we forecast the precision on $H_{0}$ achievable with $S/N=10$ and compared the observing time required to reach it with ground-based and space-based facilities. We find that the time delay can be determined without bias and with uncertainties as low as 1.3 days for the investigated resolutions and $S/N$ values when we combine time-delay measurements of multiple absorption lines. For a typical LSN II system (absolute magnitude $\sim-$17 mag in the rest-frame V band, source
redshift of \zs = 0.8), the required exposure times range from multiple hours for ground-based observations to a few minutes for space-based observations with the JWST. Our predictions on the precision of $H_0$ for a single lensed SN range from 14.2% for $R = 100$ and $S/N$ = 10 to 7.5% for $R = 250$ and $S/N$ = 20, enabling a 1% determination of $H_0$ from $\sim$20 lensed SNe in the coming years.
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All authors J. Grupa, S. Taubenberger, S. H. Suyu, D. Sluse, S. Huber, C. Vogl
Instrumentation and Methods for Astrophysics
RadialPaths: Radial profiles in multi-centred astronomical structures
Rafael S. de Souza
Radial profiles are routinely used to locate structural changes within resolved astronomical systems, but they generally define radial position relative to a single centre. In interacting, clumpy, or otherwise multi-centred structures, the radial location assigned to a feature can depend on the adopted centre. We introduce a centre-conditioned radial representation for connected structures with multiple centres. Distances are measured through the observed source footprint rather than across excluded background, and can be viewed as arrival times of fronts propagating from the centres. Each location is associated with the centre reached first and described by two complementary coordinates: relative centre–boundary depth and normalized progression away from that centre. For an ideal centred circular source, both reduce exactly to the familiar normalized radius $r/R$; in folded, elongated, or tailed geometries they separate because proximity to a lateral boundary and progression through the structure represent different notions of “outward”. Synthetic examples show that single-centre and equivalent-area radial descriptions do not retain the association between localized features and individual centres, whereas centre-conditioned profiles do. In two JADES DR2 systems, the resulting F277W profiles remain stable under modest changes in the adopted source footprint and one-pixel centre shifts. The construction assumes neither a light-profile law nor an overlapping flux decomposition, and the same radial geometry can be applied to registered maps of continuum light, colour, emission lines, stellar-population properties, and line-of-sight kinematics. An accompanying Python package, RadialPaths, provides the reference implementation together with documentation and online tutorials at \href{https://rafaelsdesouza.com.br/radialpaths} {GitHub}.
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Instrumentation and Methods for Astrophysics
The MegaWave Radio Surveyor
T. Joseph W. Lazio, Evgenya Shkolnik, James Aguirre et al. (+40 more)
Several Decadal-level questions in astrophysics,
exoplanets, astrobiology, and cosmology can be addressed only at low
radio frequencies inaccessible from Earth. The MegaWave
Radio Surveyor would open this largely-unexplored region of the electromagnetic spectrum with a space-based interferometer to (1)~Track the space weather of other
stars; (2)~Detect magnetically-generated emission from
exoplanets to probe their interiors and assess
magnetic shielding of their atmospheres; (3)~Probe the Universe's
evolution during the Dark Ages via the highly-redshifted HI hyperfine line; and (4)~Assess the role of
cosmic rays and
magnetic fields in the
cosmic web. An Astrophysics Strategic Technology & Research Accelerator (ASTRA) Initiative concept, the MegaWave
Radio Surveyor's science objectives respond to the Pathways to Discovery Decadal Survey and three other National Academies studies, and it would serve as a Formative Era mission in the Enduring Quests, Daring
Visions roadmap. Developments in U.S. space industries enable this observatory to be realized. The MegaWave
Radio Surveyor would offer a versatile, scalable, and resilient architecture capable of sensitive and simultaneous observations below 45~MHz and unprecedented angular resolution at these frequencies. The concept builds upon NASA's Sun
Radio Interferometer Space Experiment (SunRISE),
Star-
Planet Activity Research CubeSat (SPARCS), and Lunar Surface Electromagnetics Experiment (LuSEE-Night). The MegaWave
Radio Surveyor could leverage multiple elements of the Artemis program, such as access to and beyond cislunar space and communications, and there are opportunities to infuse new autonomy/AI modes for mission operations. By opening one of the last windows in the electromagnetic spectrum and pioneering space interferometry at unprecedented scales, the MegaWave
Radio Surveyor would establish a transformational capability.
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All authors T. Joseph W. Lazio, Evgenya Shkolnik, James Aguirre, Stuart D. Bale, Judd Bowman, Ruby Byrne, Joseph Callingham, Tracy E. Clarke, Ivey Davis, Tim Dolch, Peter Driscoll, Anastasia Fialkov, Steven Furlanetto, Simona Giacintucci, Ravit Helled, Jacqueline Hewitt, Phil Hopkins, Andrea Isella, Daniel Jacobs, Eloy de Lera Acedo, Melodie M. Kao, Mary Knapp, L.V.E. Koopmans, Nicholas Kern, Jasmina Lazendic-Galloway, Susan T. Lepri, R. O. Parke Loyd, James P. Lux, James P. Mason, Raul Monsalve, Miguel Morales, Julian B. Muñoz, Rachel Osten, J. Sebastian Pineda, Jonathan Pober, Sam B. Ponnada, Leslie A. Rogers, Saurabh Singh, Jake D. Turner, Jackie Villadsen, Philippe Zarka, John ZuHorne, Ellen Zweibel
Earth and Planetary Astrophysics
Non-equilibrium condensation of the first Solar System solids
Sebastien Charnoz, Jérome Aleon, Marc Chaussidon et al. (+3 more)
Primitive meteorites (chondrites) consist of an out-of-
equilibrium assemblage of minerals formed during the assembling of our Solar Nebula. The conditions under which their precursors condensed remain unclear as a result of subsequent re-processing in the protoplanetary disk or in asteroidal parent bodies. Chondrites are classified into three main classes enstatite (EC), ordinary (OC), and carbonaceous (CC) distinguished by different bulk composition and oxidation state. While
equilibrium condensation models explain the composition of some of their refractory components they do not explain the emergence of three mineralogical classes. Moreover, the low pressures, steep temperature gradients, and short dynamical transport timescales in forming protoplanetary disks likely hindered
equilibrium. Here we test the hypothesis that chondrite precursors formed via kinetic non-
equilibrium condensation. Using a new time-dependent condensation model, we show that varying the cooling rate and pressure produce only three types of mineralogies. Departure from
equilibrium yields increasingly oxidized and hydrous mineralogies. When projected into a Urey-Craig diagram, the predicted mineralogical types fall close to the redox states of EC, OC, and CC chondrites. These results suggest that the mineralogical diversity of chondrites may reflect, in part, local condensation kinetics, offering an alternative to large-scale variations of oxidation conditions.
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All authors Sebastien Charnoz, Jérome Aleon, Marc Chaussidon, Paolo Sossi, Yves Marrocchi, Patrick Franco
Solar and Stellar Astrophysics
Active nests at solar maximum: How nested flux emergence dominated flaring activity and structured the heliosphere
Adam J. Finley, Allan Sacha Brun, Antoine Strugarek et al. (+5 more)
Multi-viewpoint observations from near-Earth satellites and ESA's Solar Orbiter enable a global view of the Sun. This continuous coverage is essential for characterising active nests. We investigated how the formation of active nests during the maximum of solar cycle 25 affected the Sun's flaring activity and large-scale
magnetic field. Active nests were identified from their persistent activity in Carrington coordinates. For each nest, we monitored the
evolution of their photospheric
magnetic field, extreme ultraviolet emission, and associated solar
flares. Their impact on the solar corona was explored through potential field source surface extrapolations and coronagraph observations. These results were then compared with in-situ measurements of solar wind speed and
magnetic field polarity. During 156 days of global monitoring in 2024, nearly 80% of all solar
flares originated from three active nests in the southern hemisphere. Two of the nests converged over several months, colliding with a burst of activity in October 2024. The third nest was linked to the emergence of NOAA active region AR13664 in May 2024. Magnetically complex NOAA active regions were more prevalent within active nests. During 2024, 28% of the 147 nested active regions were complex, compared to just 16% of the 181 regions elsewhere. In January 2025, two active nests emerged from the collision site, and a new active nest appeared in the north. This reinforced a tilted dipole
topology throughout 2025. Active nests modulated global solar activity in 2024 and shaped the solar corona and wind in 2025. Nearly continuous tracking was used to isolate their flaring and flux emergence rates. Active nest migration was driven by the emergence of
magnetic flux, implying a coherent sub-surface origin. By anchoring the coronal
magnetic field, active nests created more favourable source regions for solar wind connectivity studies.
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All authors Adam J. Finley, Allan Sacha Brun, Antoine Strugarek, Barbara Perri, Daniel Müller, Miho Janvier, Andy S H To, Henrik Eklund
Cosmology and Nongalactic Astrophysics
The Impact of Magnitude Uncertainties and K-corrections on Standard Siren Measurements of the Hubble Constant
M. Pálfi and P. Raffai
Gravitational-wave standard sirens provide an independent probe of the Hubble constant. Dark siren analyses that rely on
galaxy catalogues are sensitive to catalogue-related uncertainties. While incompleteness, weighting schemes, and
redshift errors have been studied extensively, the impact of magnitude uncertainties and K-corrections has received little
attention so far. We assess how magnitude errors and K-corrections propagate into the Hubble constant inference, and compare their impact to that of realistic spectroscopic
redshift errors to determine their relevance. We use a modified version of the gwcosmo Python package to construct line-of-sight
redshift priors from a complete, volume-limited mock
galaxy catalogue up to $z<0.2$. We simulate and analyse a sample of $\sim200$ binary black hole events with luminosity weighting in the $B$- and $K$-bands and test different uncertainty models for
redshifts, magnitudes, and K-corrections. The choice of luminosity-weighting scheme has a substantial impact on the inferred Hubble constant posterior, with the direct $B$- and $K$-band comparison producing differences comparable to the largest uncertainty-induced changes. Spectroscopic
redshift errors produce the largest integrated changes in the Hubble constant posterior among the tested uncertainty treatments. Photometric magnitude uncertainties lead to substantially smaller, band-dependent deviations. In the $K$-band, the tested K-correction treatments have only a minor impact in the present low-
redshift mock analysis, with the empirical correction slightly reducing the integrated deviation relative to the no-correction case. In realistic, flux-limited catalogues with larger localization areas and photometric or mixed
redshift errors, the relative impact of magnitude uncertainties is expected to be even smaller, indicating that they need not be prioritized in near-future dark siren analyses.
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Astrophysics of Galaxies
Phase-Space Diagnostics for Dwarf Galaxies in Cluster Environments
Anna Ivleva, Rhea-Silvia Remus, Klaus Dolag et al. (+3 more)
Ongoing effort is devoted to observing spectroscopic samples of dwarf
galaxies in clusters, allowing the analysis of their distribution and associated trends in projected phase-space (PPS), i.e. line-of-sight velocity vs. projected clustercentric distance. By utilizing the resolved baryonic
halos inside the
galaxy clusters of a cosmological simulation from the Magneticum suite, we complement on prior studies with dedicated focus on the dwarf
galaxy population ($M_\ast<10^9\,M_\odot$) and correlations between infall time and location in PPS. The inferred trend recovers the radial correlation reported by prior works, but we find a significant fraction ($\geq30\%$) of recently accreted
galaxies at locations that were previously predicted to be dominated by ancient infallers. Splitting the diagram with an infall time threshold of 3 Gyr, we develop a detailed infall time template in PPS. We provide our data to allow observers to statistically infer the time of infall of their sample when placing them on the PPS. Additionally, we review the trajectories in PPS of different orbits and their dependence on the observer's orientation. Compared to massive
galaxies, we find a much broader radial distribution for dwarfs in 3D PS. Utilizing a set of high-resolution idealized simulations, we predict strongly altered orbits for dark matter-deficient
galaxies.
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All authors Anna Ivleva, Rhea-Silvia Remus, Klaus Dolag, Lucas M. Valenzuela, Jonah S. Gannon, Duncan A. Forbes
High Energy Astrophysical Phenomena
Synchrotron self-Compton Reverse Shock in Energy-Injection and Radiative Scenarios
Fraija Nissim, Betancourt-Kamenetskaia Boris, Galván Antonio et al. (+1 more)
Gamma-ray bursts (GRBs) are among the most energetic extragalactic transients, providing a unique laboratory to investigate the physical origin of the diverse morphologies observed in high-energy light curves and spectra. These morphologies, interpreted through synchrotron and synchrotron self-Compton (SSC) closure relations (CRs), may depend on the circumburst density profile, energy injection, and the dynamical
evolution of the reverse shock in the adiabatic or radiative regime. We derive the SSC closure relations produced in the reverse-shock region for both thick- and thin-shell cases, considering constant-density and stratified circumburst media. The analysis assumes two power-law (PL) distributions for the electron spectral index and includes scenarios with and without energy injection from the progenitor. We show that, depending on the physical parameters, SSC emission from the reverse shock can reproduce the initial steep-decay and plateau phases commonly observed in GRB afterglows. We then compare the predicted spectral and temporal indices with those derived from PL and broken power-law (BPL) fits reported in the Second Fermi-LAT Gamma-ray Burst Catalog (2FLGC). Our results indicate that PL (BPL) light-curve fits preferentially favor scenarios with (without) energy injection. In scenarios with energy injection, the data preferentially support a constant-density environment over a stellar-wind profile.
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All authors Fraija Nissim, Betancourt-Kamenetskaia Boris, Galván Antonio, Dainotti Maria Giovanna
Cosmology and Nongalactic Astrophysics
Paleo-Detectors as a Novel Probe of Dark Matter-Nucleus Effective Interactions
Dionysios P. Theodosopoulos
Paleo-detectors are a proposed approach to the direct detection of dark matter (DM) based on the observation of DM-induced nuclear recoils. Rather than relying on large detector masses required for conventional detectors, paleo-detectors exploit extremely long integration times, using small samples of naturally occurring minerals that have resided deep underground and accumulated damage tracks over geological timescales of order a gigayear. In this contribution, we review recent theoretical predictions for the sensitivity of paleo-detectors to WIMP-
nucleus interactions within the framework of a Non-Relativistic Effective Field Theory (NREFT). We discuss both elastic and inelastic scattering processes and consider isoscalar couplings, taking into account backgrounds from
neutrinos and radiogenic sources. We present projected sensitivities of paleo-detectors for different readout and exposure scenarios and compare the reach of paleo-detectors to that of conventional direct-detection experiments. For DM masses in the range $1\ \mathrm{GeV}/c^2$-$10\ \mathrm{GeV}/c^2$, paleo-detectors are expected to achieve sensitivities exceeding those of conventional experiments for WIMP-
nucleus interactions mediated by all NREFT operators, with only a weak dependence on the read-out scenario or target mineral. For larger DM masses, $10\ \mathrm{GeV}/c^2$-$5\ \mathrm{TeV}/c^2$, paleo-detectors are projected to attain sensitivities comparable to or surpassing conventional experiments for interactions mediated by several NREFT operators, depending on the specific read-out scenario and choice of target mineral.
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