Astrophysics of Galaxies
Radio-dust connection in quasars driven by powerful ionised outflows
V. A. Fawcett, C. M. Harrison, T. Costa et al. (+8 more)
Feedback from dusty
quasars is thought to be a key driver in
galaxy evolution. Multiple studies have reported a link between dust extinction and
radio emission in
quasars, possibly attributed to winds or jets interacting with the interstellar medium. We use optical spectra from the Dark Energy Spectroscopic Instrument (DESI) to test whether ionised outflows could be driving the observed
radio-dust connection and to determine whether dust and/or colour play a role in producing high-velocity ionised outflows in
quasars. Based on a sample of 3418 DESI
quasars at 0.5 < z < 0.9, we constrained the [OIII]$\lambda$5007 kinematics by fitting the spectra with PyQSOFit and comparing the observed trends among the [OIII] outflow velocity and the line-of-sight dust extinction E(B-V), optical-to-mid-infrared (MIR) colour g-W2, and L6$\mu$m/L5100A (a proxy for MIR excess). Utilising
radio data from the LOFAR Two-metre Sky Survey (LoTSS) DR2, we also explored the link between
radio, dust, and outflows. We find that the link between
radio emission and dust obscuration is driven by sources hosting high-velocity ionised outflows. However, we find no significant trend between the [OIII] outflow velocity and E(B-V), which suggests dust extinction alone is not a significant factor in determining whether a
quasar hosts a powerful ionised outflow. On the other hand, we find a clear positive trend between g-W2 and outflow velocity, even after controlling for luminosity. We suggest this is due to a connection between a MIR excess (boosting the W2 band) and outflows, which is supported by a positive trend between L6$\mu$m/L5100A and outflow velocity. Our results point to a scenario in which outflows shock the surrounding dust and gas, heating the dust and boosting both the MIR and
radio emission.
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All authors V. A. Fawcett, C. M. Harrison, T. Costa, D. M. Alexander, C. Andonie, H. Haidar, R. D. Shepherd, C. L. Sargent, M. J. Temple, C. Circosta, D. J. Rosario
Cosmology and Nongalactic Astrophysics
Comment on `Measuring the Hubble Constant Using Strongly Lensed Gravitational Wave Signals'
Jason S.C. Poon and Otto A. Hannuksela
In Huang et al (JCAP08(2023)003), the work claimed that the Hubble constant can be constrained from lensed gravitational waves, despite the absence of information on GW source
redshift or Einstein radius (angular size of the lens), as long as lens
redshift is provided independently. To demonstrate, the authors set up a singular isothermal sphere lens model and applied Fisher information
matrix and
Bayesian parameter estimation on injected lensed GWs. However, their conclusion contradicts our previous work on degeneracies of GW lens system parameters. In this comment, we illustrate that Hubble constant cannot be measured with lens
redshift alone, in the absence of source
redshift or (Einstein radius).
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Cosmology and Nongalactic Astrophysics
Investigating the magnetic field in the inter-cluster filament between Abell 3667 and Abell 3651 with POSSUM
C. Stuardi, S. P. O'Sullivan, L. Rudnick et al. (+19 more)
[Abridged abstract] The objective of this study is to measure the
magnetic field within the prominent inter-cluster filament recently detected in X-rays by the extended ROentgen Survey with an Imaging
Telescope Array (eROSITA). This filament spans over 13 Mpc projected on the sky, connecting the
galaxy clusters Abell 3667 and Abell 3651. We employed the Polarisation Sky Survey of the Universe's Magnetism (POSSUM) Rotation Measure (RM) grid to isolate the RM dispersion and median value of background polarised sources induced by the filament's magnetised
plasma, and to infer the strength of this
magnetic field. The filament region is sampled by 54 background polarised sources. After subtracting the foreground Galactic RM, we detected a marginal residual RM dispersion in the filament region of $6.9\pm3.6$ rad/m$^{2}$, together with a coherent residual RM signal with median $6.3\pm1.3$ rad/m$^{2}$. Assuming simplified single-scale
magnetic-field models and adopting informed priors on the thermal electron density distribution derived from the X-ray analysis, we constrained the
magnetic field strength to the range 0.1-3.5 $\mu$G within 95$\%$ confidence, with preferred values around 0.2-0.3 $\mu$G depending on the assumed
magnetic-field coherence scale. However, we also found that the Galactic foreground RM in this region is highly structured on angular scales comparable to the extent of the filament itself, representing a major source of uncertainty for the RM analysis. Our results provide the first
magnetic field constraints based on Faraday rotation measurements in an individual X-ray-detected inter-cluster filament, with field strengths consistent with theoretical expectations for gas in bridges and cluster outskirts. Our analysis also highlights the critical importance of accurately modelling Galactic RM foregrounds for future studies of extra-galactic magnetism with POSSUM and the SKA.
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All authors C. Stuardi, S. P. O'Sullivan, L. Rudnick, G. Bernardi, A. Bonafede, J. Dietl, T. Akahori, D. Alonso-López, C. Anderson, E. Carretti, B. M. Gaensler, G. Heald, F. Loi, Y. K. Ma, E. Osinga, G. Pignataro, C. Riseley, X. Sun, A. Thomson, C. L. Van Eck, T. Vernstrom, J. L. West
High Energy Astrophysical Phenomena
Decisive evidence for a global cosmic-ray feature in gamma-ray data
Fernando Valenciano, Pedro De la Torre Luque, Daniele Gaggero et al. (+1 more)
We analyze 17 years of Fermi-LAT data to study the diffuse $\gamma$-ray emission along the Galactic plane and its connection to
cosmic-ray (CR) propagation. Accounting for correlated instrumental systematics, we find decisive evidence for a spectral break at $\sim20-30$ GeV, present across the inner Galactic disk, with a preference of $\Delta\chi^2=39.78$ ($4.44 \sigma$ global). The energy and amplitude of this feature are in striking agreement with the spectral feature observed in local CR
nuclei, indicating that it is a global property of the Galactic disk rather than a local phenomenon. The measured slope change, $\Delta\gamma \simeq 0.20$, is consistent with local CR data and with expectations from a transition in the CR
diffusion regime from Kolmogorov to Kraichnan
turbulence. Our results provide strong evidence that diffuse $\gamma$-ray emission along the Galactic disk is dominated by $\pi^0-$decay emission up to a hundred GeV. These findings provide key insights into the origin of the CR spectral hardening and the propagation of CRs throughout the
Galaxy, and illustrate how this multimessenger approach can be used to probe the origin of features in the CR spectra, such as the long-studied CR Knee.
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All authors Fernando Valenciano, Pedro De la Torre Luque, Daniele Gaggero, Jorge Martin Camalich
Earth and Planetary Astrophysics · Cross-listed from physics.flu-dyn
Internal heating in rapidly rotating convection is not a shortcut to geostrophic turbulence
Justin A. Nicoski, Tobias G. Oliver, Stefano Maffei et al. (+1 more)
Convective
turbulence in
planets and
stars is often driven by internal heating. This forcing mechanism has also been proposed as a means of accessing the
diffusion-free scalings of the geostrophic
turbulence (GT) regime at modest forcing. We test this with the asymptotically reduced quasi-geostrophic model, which is formally valid in the limit of vanishing Ekman number, $Ek \rightarrow 0$, and retains the Prandtl number as an independent parameter. We find no such shortcut: the Nusselt and Reynolds numbers are no closer to their
diffusion-free predictions than in the boundary-heated case, and at $Pr = 7$ they are further from them; the predicted $Pr^{-1/2}$ collapse fails; and the prefactor depends on the form of the heating. Our no-slip/stress-free cases track the radiatively driven simulations of Hadjerci et al. (2024) case by case, yet a $25\%$ variation in $Nu$ persists between sweeps that share the same reduced Rayleigh and Prandtl numbers but differ in Ekman number. Those data span only the narrow range of forcing over which the compensated Nusselt number is stationary; across the wider range accessible to the reduced model it rises to a maximum and then falls. We argue that bulk transport scalings are incomplete diagnostics of GT, whereas the saturation of the interior mean temperature gradient and of the vertical velocity kurtosis remain reliable indicators.
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All authors Justin A. Nicoski, Tobias G. Oliver, Stefano Maffei, Michael A. Calkins
Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc
Inspiralling Binary merger parameter reconstruction with lunar and satellite Laser Ranging
Miguel Vanvlasselaer
Precision tracking of Earth–Moon and Earth–satellite ranges offers a novel, low-frequency avenue for detecting gravitational waves from inspiralling massive black hole binaries, complementary to space-based interferometers. In this paper, we propose a first study of the reconstruction of the binary parameters from a synthetic set of range observations. Set-up: Assuming an ideal unperturbed Keplerian motion for the earth-satellite binary, we develop a framework for reconstructing the chirp mass $\mathcal M_c$ and luminosity distance $D_L$ of chirping sources from the perturbations they induce on ranging observables, using both Lunar
Laser Ranging (LLR) and a two-satellite ranging configuration (GUEST) as concrete case studies. Result: We find that chirp-mass recovery tightly converges as a power law in SNR ($\sigma_{M_c}/M_c \propto \mathrm{SNR}^{\alpha}$, $\alpha \simeq -1$ to $-1.8$) for both LLR and GUEST. In contrast, the luminosity distance suffers from a severe, SNR-independent degeneracy with the sky-orientation angles in the LLR configuration, yielding fractional biases and uncertainties of tens to over a hundred percent regardless of signal strength. The two-satellite GUEST configuration breaks this degeneracy and restores a convergent, SNR-dependent recovery of $D_L$ comparable in scaling to that of the chirp mass. These results demonstrate that multi-baseline ranging architectures are essential for extracting luminosity-distance information from ranging-based gravitational wave searches, while chirp-mass measurements remain reliably accessible even with a single ranging baseline such as the Earth–Moon system.
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Earth and Planetary Astrophysics
Impacts of Correlated Noise on Retrievals of Exo-Earth Atmospheres
Nicole Wolff, Bruce Macintosh, Tyler D. Robinson et al. (+6 more)
The Habitable Worlds Observatory (HWO) aims to accomplish high-contrast imaging and spectroscopy of true Earth analogs for the first time. However, high-contrast spectroscopy with HWO may be limited by residual speckles which persist after deformable mirror correction and post-processing, hindering atmospheric characterization. Previous studies of self-luminous giant
planets showed that neglecting spectrally correlated errors due to speckles results in biased inferences of planetary parameters. Currently, HWO
retrieval studies generate spectra without noise spectral correlations. We present a Gaussian Process model of correlated noise of known properties in simulated HWO exo-Earth spectra, and the integration of this noise source into the forward and inverse modeling tool rfast. We quantify the impact of correlated noise on inferred molecular abundances and planetary properties across the ultraviolet/visible/near-infrared bandpass, for varying spectral resolutions (R), signal-to-noise ratios (SNR), and noise correlation length-scales (L). We find that, at the fiducial UV/Vis/NIR R=7/140/70 and SNR=10, including spectrally correlated noise at L=200 nm and L=10 nm yields a 57% and 161% higher average uncertainty on log oxygen abundance, compared to uncorrelated noise. Consequently, it is critical for both instrument design and post-processing
algorithms to minimize short length-scale chromaticity. Additionally, we find that a moderate resolution can constrain carbon dioxide (R$\geq 280$) and weakly detect methane (R$\geq2800$) abundances, demonstrating the benefit of a moderate resolution near-infrared spectrograph. These findings can aid the interpretation of future HWO reflectance spectra and set requirements on optical quality, instrument stability, and observing configurations.
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All authors Nicole Wolff, Bruce Macintosh, Tyler D. Robinson, Sarah Blunt, Jean-Baptiste Ruffio, Beck Dacus, Alex Madurowicz, Marshall Perrin, Laurent Pueyo
Earth and Planetary Astrophysics
On the Impact of Correlated Noise and Spectral Resolution on the Retrieval Analysis of the Habitable World Observatory
Ji Wang, Philipp A. Huber and Sascha P. Quanz
Finding signs of life elsewhere in the universe is the holy grail of the field of
exoplanets. Future space missions such as the Habitable World Observatory (HWO) are under development to search for biosignatures in
exoplanets. We investigate the impact of correlated noise and spectral resolution on the retrieved biosignature chemical abundances. At the nominal spectral resolving power R=140 for HWO, we show that in 40% of the simulated runs the retrieved biosignature (H$_2$O and O$_2$) abundances are at least 1-$\sigma$ off the input ground truth. At R=1000, the 1-$\sigma$ inaccuracy rate drops to 10%. We provide an empirical relationship between the retrieved biosignature abundance uncertainty and the amplitude of the correlated noise. As part of the mitigation plan to reduce the impact of correlated noise on
retrieval accuracy at low spectral resolution, we investigate the synergy between the HWO and LIFE space missions that cover ultraviolet, optical, and thermal-infrared wavelengths. After considering clouds and their effect on
planet albedo, we find that the two missions are complementary in that (1) more biosignatures (H$_2$O, CO$_2$, O$_2$, and O$_3$) are detectable with a broader wavelength coverage; (2)
retrieval uncertainty improves with the joint HWO+LIFE data set; and (3) LIFE is more sensitive to the atmospheric temperature profile, surface pressure, and
planet radius. This work provides evidence to support the choice of a medium resolution at R=1000 instead of R=140 for HWO and a quantitative relationship between the retrieved abundance uncertainty and the level of correlated noise at different spectral resolutions.
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Astrophysics of Galaxies
Shock-heated Away: The Impact of Radiative Cooling on Gas-Phase Transitions in Supernova Remnants
Zuzanna Kocjan, Benedikt Diemer, Vadim A. Semenov et al. (+2 more)
Supernova (SN) feedback plays a central role in regulating the structure of the interstellar medium (ISM) through the injection of energy and momentum. The amount of hot gas produced by a
supernova is a key quantity that determines how efficiently SN feedback heats the ISM and drives mass exchange between its different gas phases, here defined as cold ($T < 10^3\, \mathrm{K}$), warm ($10^3\, \mathrm{K} < T < 2\times10^4\, \mathrm{K}$), and hot ($T > 2\times10^4\, \mathrm{K}$) gas. However, previous studies have reported discrepant amounts of hot gas formed under otherwise similar ambient conditions. To resolve these disagreements, we quantify the amount of hot gas produced by individual SN explosions using a suite of controlled simulations spanning a broad range of ISM environments that include both uniform and turbulent, multiphase backgrounds. We show that radiative cooling is a key factor regulating hot-gas production, and that differences in cooling efficiency can account for some of the discrepancies reported in the literature. We derive a simple predictive relation for the peak hot-gas mass attained during the
evolution of a
supernova remnant in terms of the mean ambient density, the initial phase distribution, and the efficiency of gas cooling, which we parameterize as the cooling time over a key temperature range of $10^{4.5}\,\mathrm{K} \lesssim T \lesssim 10^{5.1}\,\mathrm{K}$. Finally, using tracer particles, we distinguish the evaporation of cold and warm gas into the hot phase and derive physically motivated expressions for the evaporation efficiency. Our results provide simple, predictive relations for hot-gas production and phase transitions that can be incorporated into subgrid models of SN feedback in
galaxy formation simulations.
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All authors Zuzanna Kocjan, Benedikt Diemer, Vadim A. Semenov, Shmuel Bialy, Uri Malamud
High Energy Astrophysical Phenomena
Galactic Science with Ultra-High Angular Resolution X-ray Imaging
Paul A. Draghis, Jeremy Hare, Mayura Balakrishnan et al. (+8 more)
Milli- to micro-arcsecond X-ray imaging will open a new observational regime for Galactic astrophysics by resolving physical scales that are inaccessible to current X-ray observatories. This white paper highlights the science enabled by such capabilities across four broad questions: how particles are accelerated, how
stars die, how
accretion is fueled, and what populations of X-ray sources inhabit the
Galaxy. Ultra-high angular resolution will enable many new studies, such as resolving shocks and jets, measuring proper motions, parallaxes, and binary orbits, and providing secure multiwavelength counterpart identifications in crowded environments such as the Galactic Center and globular clusters. Combined with high-time-resolution observations, these measurements will connect variability and transient events to the physical structures in which they originate, while coordination with gravitational-wave,
neutrino, $\gamma$-ray,
radio, optical, and infrared facilities will provide spatial information needed to identify and characterize multi-messenger sources. In addition to defining the science cases, this paper presents a curated list of compelling targets spanning various angular resolutions and outlines the complementary specifications necessary to maximize the scientific outcome. Accomplishing these science goals will require an instrument with high angular resolution, precise astrometry, substantial collecting area, sufficient spectral and timing resolution, and high dynamic range imaging capabilities.
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All authors Paul A. Draghis, Jeremy Hare, Mayura Balakrishnan, Poshak Gandhi, Tyler Holland-Ashford, Margarita Karovska, Thomas Maccarone, Herman L. Marshall, Mark Reynolds, Malgosia Sobolewska, Ryan Tanner
Astrophysics of Galaxies
Super-Eddington Little Blue Dots May Reionize Helium Too Early
Christopher Cain, Brent Smith, Gibson B. Bowling et al. (+5 more)
The James Webb Space
Telescope (JWST) has identified an abundant population of faint Active Galactic
Nuclei (AGN) at $z \gtrsim 4$ which display broad emission lines, compact morphologies, and blue ultraviolet–optical continua. These “Little Blue Dots' (LBDs) have been suggested to belong to the same family of objects as the more controversial “Little Red Dots' (LRDs), with differences between the two largely owing to viewing angle effects. In this scenario, super-Eddington
accretion resulting in high Extreme UV (EUV) and weak X-ray emission is invoked to explain the properties of both populations. We study the consequences of this super-Eddington scenario for the timing of Helium reionization. We find that observations which support an end to helium reionization no earlier than $z \approx 3$ disfavor scenarios in which the majority of observed $3 \lesssim z \lesssim 7$ LBDs are highly super-Eddington. For our fiducial super-Eddington
accretion scenario, we find that the fraction of the LBD population in this state must be $\lesssim 10\%$, assuming LBDs make up $5\%$ of the $M_{ m UV} < -18$
galaxy population and have average escape fractions of $15\%$, comparable to recent observations. Our constraint assumes that LBDs dominate the Helium reionization budget, and would be tighter if bright
quasars also contributed significantly. For a majority of LBDs to be super-Eddington, they would need to have small escape fractions ($\lesssim 1.5\%$) and/or be less abundant than observations suggest. Our conclusions are sensitive to the shape of the EUV spectra of super-Eddington black holes, motivating further study.
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All authors Christopher Cain, Brent Smith, Gibson B. Bowling, Yongda Zhu, Lily Whitler, Rafael Ortiz III, Anson D'Aloisio, Rogier Windhorst
Astrophysics of Galaxies
The GECKOS survey: Assembly history of the lenticular galaxy NGC 3957
Yuchen Ding, Marie Martig, Ling Zhu et al. (+24 more)
We analyse the assembly history of the edge-on lenticular
galaxy NGC 3957 using deep integral-field spectroscopic MUSE data from the GECKOS survey. By applying a dust-corrected Multi-Gaussian Expansion and a population-orbit superposition model, we disentangle the
galaxy's stellar kinematics, age, and
metallicity. We dynamically decompose the
galaxy and identify three distinct components: a dynamically-cold main disc, a compact Nuclear Stellar Disc (NSD), and a hot component. The NSD emerges as the youngest and most metal-rich component ($t = 6.9 \pm 0.4$ Gyr; $[Z/H] = 0.49 \pm 0.06$ dex), implying that the stellar bar is a long-lived structure that formed at least $\sim 7$ Gyr ago. The main stellar disc is dynamically cold ($\sigma_z \sim 20-30$ km/s), precluding any significant mergers over the last $\sim 8$ Gyr, and exhibits a strong positive age gradient (younger inside, older outside) beyond the bar radius. Synthesising these dynamical fossil records, NGC 3957 likely evolved as a `faded spiral' in a small-to-medium group environment. Its outer disc might passively fade due to mild gas starvation, while the bar fuelled prolonged central
star formation. Comparison with S0s in the Fornax cluster reveals that this combination of internal secular
evolution and mild starvation produces `outside-in' fading signatures that could mimic the environmental stripping typically seen in dense clusters.
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All authors Yuchen Ding, Marie Martig, Ling Zhu, Amelia Fraser-McKelvie, Ryan Leaman, Glenn van de Ven, Jesse van de Sande, Francesca Pinna, Eric Emsellem, Francesca Fragkoudi, Yunpeng Jin, Adriano Poci, Camila de Sá Freitas, Matthew Frosst, Runsheng Cai, Scott M Croom, Timothy A Davis, Rory Elliott, Michael R Hayden, Jesús Falcón-Barroso, Dimitri A Gadotti, Antonino Marasco, Lucas M Valenzuela, Zixian Wang, Emily Wisnioski, Meng Yang, Tayyaba Zafar
Astrophysics of Galaxies
Spatially-Resolved Spectra of Diffuse Galactic Light using 10.8 M DESI Sky Fibers
Andrew K. Saydjari, Bruce T. Draine, Timothy D. Brandt et al. (+49 more)
Using 10.8 million “blank” sky spectra from the DESI Year 3
dataset, we measure the diffuse galactic light (DGL) spectrum in the optical at spectral resolution $R \sim 4000$ by correlating with far-infrared emission from IRAS. Subdividing the sky into 54 deg$^2$ pixels (HEALPix, NSIDE = 8), we map the variation of the DGL correlation spectrum and nebular emission lines across the DESI footprint in the high-Galactic-latitude sky. The increased data volume over previous SDSS-based analyses enables several new detections in the DGL, including scattering both onto and out of the line of sight from neutral interstellar sodium and potassium. We further detect direct emission from ro-vibrational transitions of molecular hydrogen in the near-infrared with an absolute radiance of $0.65\substack{+0.13 \\ -0.12}\times10^{-9}~{\rm erg\, cm^{-2}\,s^{-1}\,sr^{-1}}$, roughly consistent with theoretical expectations, but with an apparent ortho-to-para line ratio that is lower by a factor of $0.60\substack{+0.28 \\ -0.27}$. We confirm previous detections of extended red emission (ERE) in the DGL and map its spatial variation. Our spatially resolved DGL maps provide important observational constraints for the radiative transfer efforts that are now possible with recent 3D models of the Milky Way.
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All authors Andrew K. Saydjari, Bruce T. Draine, Timothy D. Brandt, Edward F. Schlafly, Arjun Dey, Douglas P. Finkbeiner, J. Aguilar, S. Ahlen, C. Allende Prieto, A. Anand, F. Beutler, D. Bianchi, D. Brooks, A. Carnero Rosell, T. Claybaugh, A. de la Macorra, P. Doel, A. Font-Ribera, J. E. Forero-Romero, E. Gaztañaga, Satya Gontcho A Gontcho, G. Gutierrez, J. Guy, K. Honscheid, T. Karim, D. Kirkby, A. Kremin, O. Lahav, A. Lambert, M. Landriau, L. Le Guillou, A. Meisner, R. Miquel, J. Moustakas, S. Nadathur, E. Paillas, W. J. Percival, I. Pérez-Ràfols, F. Prada, C. Ravoux, G. Rossi, L. Samushia, E. Sanchez, C. Saulder, D. Schlegel, M. Schubnell, R. Sharples, J. Silber, M. Siudek, G. Tarlé, B. A. Weaver, R. Zhou
Cosmology and Nongalactic Astrophysics
AXIS Could Have Accessed Dark Matter Decays
Joshua W. Foster, Inci Karaaslan, Gordan Krnjaic et al. (+1 more)
The Advanced X-ray Imaging Satellite (AXIS) was a mission concept designed to improve upon the sensitivity and spatial resolution of the Chandra X-ray Observatory and XMM-Newton. Although AXIS was not selected for implementation, the concept study defined a mature instrument design with low-background, arcsecond imaging over the $0.3$-$10$ keV energy range, a large effective area, and a wide field of view. These capabilities provide a useful
benchmark for the dark matter decay sensitivity of future X-ray observatories. We estimate the reach of a future AXIS-like instrument for narrow
photon lines from decaying keV-scale dark matter, including
axion-like particles and sterile
neutrinos. For Galactic center observations, we find projected lifetime sensitivities of order $10^{31}$ s, improving upon existing limits by up to an order of magnitude over part of the keV mass range.
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All authors Joshua W. Foster, Inci Karaaslan, Gordan Krnjaic, Nimrod Shapir
Astrophysics of Galaxies
Magnetic destabilisation in disc galaxies: Filament/feather formation
Raghav Arora, Oscar Agertz, Christoph Federrath et al. (+1 more)
Gas gravitational instability plays a crucial role in secular galactic
evolution, but the role played by
magnetic fields in mediating this instability - despite their dynamical relevance and ubiquity - is still not understood. To investigate this question we conduct a parameter study using numerical simulations of 3D isolated disc
galaxies that are initialized in
equilibrium, but have a range of initial magnetisation, quantified by $\beta \in \{0.1, 0.5, 1, 10, 100, \infty\}$, where $\beta$ is the ratio of thermal to
magnetic pressure. We analyse how
magnetic field strength influences the formation of dense filaments and feathers driven by gravitational instability. The simulations show that filament growth rate and spacing are significantly altered by dynamically strong fields ($\beta \lesssim 10$), and that these effects depend on the value of $\beta$ and strength of shear in the disc.
Magnetic fields either stabilise or destabilise, with destabilisation dominating in regions with low $\beta$, and low shear. This makes the destabilisation particularly important in dwarf
galaxies with low-shear rotation curves. Filament spacings are similarly affected differently in different galactic regions, depending upon the local field strength and shear. Our results are in good agreement with predictions from the magneto-Jeans mechanism.
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All authors Raghav Arora, Oscar Agertz, Christoph Federrath, Mark R. Krumholz
High Energy Astrophysical Phenomena
A Similarity Theorem and Its Breakdown in Atomic Black Hole Accretion
Marcus DuPont
Atomic gas in a point-mass potential possesses an exact similarity that survives time dependence, two-body atomic microphysics, and a specified class of radiation and feedback laws. At fixed ambient temperature and composition, $M_\bullet\mapsto\lambda M_\bullet$ and $n_\infty\mapsto\lambda^{-1}n_\infty$ enlarge radii and times by $\lambda$ while preserving dimensionless profiles, optical depths, Eddington ratios, and variability. Here $M_\bullet$ is the central mass, $n_\infty$ the ambient number density, and $\lambda>0$ the scale factor. We prove this rescaling unique within the class. The
symmetry also locates its boundary during rapid growth. Define the fractional mass gained in one Bondi time as $\epsilon_{\rm grow}=\dot M_\bullet t_{\rm B}/M_\bullet$, where $\dot M_\bullet$ is the retained rate and $t_{\rm B}$ the Bondi time. This quantity equals $\dot R_{\rm B}/c_\infty$, the expansion speed of the Bondi radius $R_{\rm B}$ in units of the ambient sound speed $c_\infty$; hence $\epsilon_{\rm grow}=1$ is sonic dilation. A retained law $\dot M_\bullet\propto M_\bullet^p$ with $p>0$ reaches this boundary after a finite increase in mass and leaves at most $(p\epsilon_0)^{-1}$ additional Bondi times, where $\epsilon_0$ is the initial loading. If retained, the canonical hyper-Eddington example has already crossed. Independently, no nontrivial stationary growing profile preserves both the atomic similarity and its self-consistent flux. The
theorem therefore unifies radiating Bondi and feedback-regulated scalings and identifies where a relaxed fixed-mass continuation loses control.
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Earth and Planetary Astrophysics
ExoMOD II. A Statistical Model of Transit Timing Variations in Kepler Multi-Planet Systems
David Nesvorny, Daniel A. Yahalomi, David Kipping et al. (+2 more)
In Paper I (Nesvorný et al. 2026), we forward modeled transit observations of the Kepler
telescope to characterize the orbital properties of close-in planetary systems. The new population model, ExoMOD, was calibrated on Kepler's DR25 data. Here we use ExoMOD to statistically predict Transit Timing Variations (TTVs) from gravitationally interacting
planets in the close-in systems, and compare these predictions with TTVs actually detected in the Kepler data. We find that
planet-
planet interactions are not expected to produce significant short-period TTVs, $P_{\rm TTV}/P_{\rm orb}<10$, where $P_{\rm TTV}$ and $P_{\rm orb}$ are the TTV and orbital periods, often enough to explain the short-period TTV signals inferred from the Kepler data. Most measured short-period signals must therefore have a different origin. The statistics of long-period TTVs – likely arising from the gravitational interaction between
planets – indicates that single transiting
planets have TTV-inducing companions nearly as often as doubles, thus ruling out multiplicity distributions with a prevalence of intrinsic singles. The fraction of
planets with measured long-period TTVs increases to $\simeq 15$-18% for observed multiplicities $m \geq 3$, suggesting a change in the orbital architecture. High-multiplicity planetary systems have low gap complexities and probably retained a
memory of their formation conditions. Ultimately, our work aims at developing a more informative feedback between observations and
planet formation theories.
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All authors David Nesvorny, Daniel A. Yahalomi, David Kipping, Cristian Beauge, Sarah C. Millholland
Earth and Planetary Astrophysics
ExoMOD I. A Forward Model for the Orbital Architecture of Kepler Multi-Planet Systems
David Nesvorny, Daniel A. Yahalomi, David Kipping et al. (+1 more)
Transit observations only detect
planets with favorable, near edge-on orientation of orbits as seen by a distant observer, which leaves much freedom for various interpretations in terms of the underlying planetary system architecture. Here we forward model transit observations of the Kepler
telescope to characterize the orbital properties of close-in planetary systems. We make sensible choices about the underlying distributions of
planet radii, masses and orbital periods, parameterize the orbital excitation with the Angular Momentum Deficit (AMD), and adopt an accurate method to account for transit detection. The fits to Kepler's DR25 data are executed with MultiNest. We find that the orbital period distributions of Kepler singles and multis are statistically different from each other – possibly a consequence of Kepler's observational baseline. The observed gap complexity distribution is reproduced when
planets in high multiplicity systems ($m \geq 5$) are assigned ideally correlated period ratios. The high-multiplicity systems probably retained a
memory of their formation conditions. The gap complexity metric also helps to constrain the AMD distribution. We find that systems with positive radius monotonicities typically harbor smaller
planets, as expected if the radius monotonicity is influenced by non-detections. A FGK dwarf in the Kepler field should host $\simeq 2.4 \pm 0.2$
planets on average with radii $0.5 < R_{\rm pl}/R_\oplus < 7$ and orbital periods $3<P_{\rm orb}<300$ d. For a detected planetary system, there is roughly a 50% chance that Kepler transit observations missed at least one inner or intermediate-period
planet.
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All authors David Nesvorny, Daniel A. Yahalomi, David Kipping, Cristian Beauge
Earth and Planetary Astrophysics
A Clearer View of HAT-P-1 b: JWST NIRSpec G395H Reveals Water, Carbon Dioxide, and Possibly Hydrogen Sulfide
Reza Ashtari, Stephen P. Schmidt, Guangwei Fu et al. (+16 more)
As part of JWST's
Exoplanet Grand Tour Survey, we use panchromatic transmission spectroscopy to connect HAT-P-1 b's previously studied optical and near-infrared atmosphere to the longer-wavelength molecular bands accessible with JWST. We present JWST NIRSpec G395H transmission spectroscopy of the hot Jupiter HAT-P-1 b over 2.7–5.3~$\mu$m, and combine the new spectrum with archival HST STIS and WFC3 observations for a 0.3–5.3~$\mu$m atmospheric analysis. We independently reduce the JWST data with the Eureka!, FIREFLy, and Tswift pipelines, finding mutually consistent transmission spectra across the G395H bandpass. Atmospheric
retrievals yield strong evidence for H$_2$O and CO$_2$ with Bayes factors of $\log_{10}B_{\mathrm{H_2O}}=8.9$ and $\log_{10}B_{\mathrm{CO_2}}=52.3$, while providing tentative evidence for H$_2$S ($\log_{10}B_{\mathrm{H_2S}}=1.4$). The joint H$_2$O and CO$_2$ constraints favor an atmosphere near chemical
equilibrium, with $\log_{10} \text{M/H}=0.99^{+0.19}_{-0.14}$, corresponding to $\sim10\times$ Solar or $\sim9\times$ relative to the near-solar
metallicity host
star, and a 3$\sigma$ upper limit of C/O $<0.52$. Because H$_2$O and CO$_2$ provide a
metallicity comparatively insensitive to vertical mixing in this temperature regime, their combined detection suggests the composition is dominated by bulk enrichment rather than strong disequilibrium transport. We find no significant evidence for clouds; instead, the persistence of molecular structure across the spectrum argues against strong cloud muting. The tentative H$_2$S signal, if confirmed, would further suggest limited photochemical processing at the pressures probed. Together, the molecular inventory, enriched
metallicity, and low C/O ratio point to an oxygen-rich atmosphere and establish HAT-P-1 b as a
benchmark for comparative studies of hot-Jupiter atmospheric composition.
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All authors Reza Ashtari, Stephen P. Schmidt, Guangwei Fu, Avinash Verma, David K. Sing, Kevin B. Stevenson, Jayesh Goyal, Katherine A. Bennett, Joshua D. Lothringer, Jacob Lustig-Yaeger, Sagnick Mukherjee, Carlos Gascón, Natalie H. Allen, Patrick McCreery, Le-Chris Wang, Mei Ting Mak, Kristin S. Sotzen, Lakeisha M. Ramos Rosado, N. J. Mayne
High Energy Astrophysical Phenomena
Exploring the sensitivity of in-ice radio detectors to cosmic ray mass composition
Nathaniel Alden, Marissa Boucher, Cosmin Deaconu et al. (+2 more)
In-ice
radio detectors have been developed primarily for the detection of high-energy
neutrinos via the Askaryan effect, but have recently been shown to also be sensitive to
cosmic ray air showers impacting the ice sheet. Using CORSIKA 8 to simulate impacting air showers, we find that the lateral width of the in-ice cascade is sensitive to the atomic mass of the primary
cosmic ray. The width of the shower core is accessible through the shape of the Askaryan
radio spectrum, while the amplitude encodes the total in-ice charge excess. Using these two observables, we show that in-ice
radio detectors can be used to measure
cosmic ray mass composition in the region above $10^{17}$eV if the in-ice receivers are placed to adequately sample the Askaryan emission pattern. We also show that the in-ice core width is highly, but not exactly, correlated with the depth of maximum particle count ($\mathrm{X}_{\mathrm{max}}$), the most commonly used observable for reconstructing
cosmic ray mass composition.
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All authors Nathaniel Alden, Marissa Boucher, Cosmin Deaconu, Abigail Vieregg, Philipp Windischhofer
High Energy Astrophysical Phenomena
Distinct Modes of Pulsar Glitch Activity Revealed by the Waiting-Time–Amplitude Morphology
Wen-Tong Liu, Wei-hua Wang, Xia Zhou et al. (+1 more)
Pulsar glitches display diverse behaviors. They are commonly labeled as "Vela-like" or "Crab-like," yet these qualitative categories do not provide reproducible quantitative boundaries. We constructed an objective classification scheme based on the joint distribution of backward waiting time $\Delta t_{-}$ and fractional glitch amplitude $\Delta\nu/\nu$. A sample of 349 glitches from 22
pulsars was compiled by cross-matching the Jodrell Bank and ATNF glitch databases. For each source, we used two-dimensional kernel density estimation (KDE) together with highest-density regions (HDRs) to derive
geometric descriptors, including the HDR area, anisotropy ratio, and out-of-HDR fraction. Hierarchical clustering of the KDE–HDR descriptors revealed two morphology classes independent of visual inspection. In this convention, the Compact class is associated with small HDR areas, elevated anisotropy, and limited peripheral occupancy. The Extended class is associated with broader HDR occupancy and stronger low-density extensions. We found that bootstrap resampling and hyperparameter sensitivity tests confirmed this partition for most sources. Nevertheless, two prolific
pulsars (PSR J0537-6910 and PSR J1341-6220) were found to occupy intermediate positions. Logistic regression identified the mean backward waiting time $\langle\Delta t_{-}\rangle$ as the strongest class predictor (in-sample $\mathrm{AUC}=0.88$; leave-one-out $\mathrm{AUC}_{\mathrm{CV}}=0.59$, reflecting the limited sample size). Additionally, a parallel analysis using $\Delta t_{+}$ recovered the same two-class structure but with reduced stability. The data suggest that the Compact class is consistent with near-complete reservoir depletion, whereas the Extended class reflects partial, avalanche-like releases. As a result, short-term measurements of $G$ in Extended-class
pulsars may underestimate the true crustal superfluid fraction.
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All authors Wen-Tong Liu, Wei-hua Wang, Xia Zhou, Fei-fei Kou
Solar and Stellar Astrophysics
An All-Sky Catalog of 6.5 Million Primary Red Clump Stars from Gaia DR3 XP Spectra
Zheng Yu and Bingqiu Chen
Red clump (RC)
stars are excellent standard candles for mapping the three-dimensional structure of the Milky Way. We construct an all-sky catalog of 6.5 million primary RC
stars using spectroscopic estimates of asteroseismic parameters inferred from Gaia DR3 low-resolution XP spectra. We train a mixture density network (MDN) on a cross-matched sample. The network maps each 343-dimensional corrected XP spectrum to estimates of $\Delta\Pi_{1}$, the asymptotic period spacing of dipole
gravity modes, and $\Delta\nu$, the large frequency separation. We select primary RC
stars using these two estimates. We release two complementary catalogs defined by different parameter-space cuts and thresholds: a high-purity Tier 1 sample of 532,189
stars with 97% purity and a high-completeness Tier 2 sample of 6,534,931
stars with 86% completeness. Both catalogs cover the full celestial sphere. We provide distances and extinction values for all
stars. We obtain a median photometric distance precision of 6% for Tier 1 RC
stars. Using the resultant distances, we independently calibrate the Gaia DR3 parallax zero-point offset. The three-dimensional density distribution traced by the Tier 2 sample extends continuously to $R\approx25$ kpc. Both catalogs are publicly available. These catalogs provide a valuable resource for Galactic archaeology, delivering a homogeneous
dataset to trace the chemo-dynamical
evolution of the Milky Way and to calibrate models of stellar populations.
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Instrumentation and Methods for Astrophysics
Fast and efficient nested sampling with BEST
Andreas Nygaard
Nested sampling is widely used for
Bayesian evidence computation, but its intrinsically sequential structure limits how efficiently it can exploit modern vectorised likelihoods and emulators. We present a new nested-sampling implementation in best, written entirely in TensorFlow and designed for efficient XLA compilation on both CPUs and GPUs. The sampler combines clustering and slice sampling with the possibility of updating several live points simultaneously. Since batching breaks the strict ordering of conventional nested sampling, we introduce sorting and history-based corrections to reduce the resulting bias in the evidence estimate. We test the sampler on Gaussian, Rosenbrock, and
multimodal likelihoods and compare its performance with JAXNS and UltraNest. The results show that accurate evidence estimates can be retained for moderate batch sizes, with $m/N_{\rm live}\lesssim 0.1$ providing a useful practical regime. Finally, using a 27-dimensional cosmological likelihood emulator, we show that batched live-point updates can substantially reduce the wall-clock time while remaining consistent with sequential sampling within the reported uncertainties. The new implementation therefore extends best with an efficient nested-sampling method tailored to fast, vectorised likelihoods and emulator-based inference.
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High Energy Astrophysical Phenomena
Relativistic outflows power a quasi-periodic eruption: constraints on energetics, mass loss, and emission mechanisms
Joheen Chakraborty, Erin Kara, Wenbin Lu et al. (+17 more)
Quasi-periodic eruptions (QPEs) are recurring bursts of X-ray radiation originating from supermassive black holes (SMBHs). They are an unprecedented type of structured, high-amplitude SMBH variability, but the physical origins of their regularity, timescales, energetics, and emission are uncertain. We present new XMM-Newton observations of the QPEs in ZTF19acnskyy/"Ansky", constituting the deepest observations of individual bursts in any source thus far. The X-ray spectra reveal time-evolving P Cygni profiles comprising blueshifted absorption and redshifted emission from L-shell transitions of Fe XIX-XXIV, with column densities $N_H\sim 10^{22-23}$ cm$^{-2}$ and bulk velocities of $|v_w/c|\sim 0.2$, indicating relativistic mass ejections during each eruption. We construct a time-dependent analytical model of a wind turning on to self-consistently compute its evolving luminosity and ionization properties, and find that the light curve and spectral lines can be simultaneously produced by a wide-angle outflow with $\dot{M}\sim 10^{-9}-10^{-8}\,M_\odot$ s$^{-1}$ kinetically powering the X-rays with an efficiency of $L_X/\dot{E}_K\sim 0.1$. For a covering fraction $f_\Omega\sim0.5$, each eruption ejects $\sim 10^{-3}\,M_\odot$ and $\gtrsim 10^{49}$ erg of kinetic energy, setting an upper bound on the QPE lifetime of $\lesssim1000$ bursts if the underlying mass reservoir is $\sim1 M_\odot$, and implying that the bursts may result in detectable multiwavelength signatures of reverberation and feedback. These measurements provide new quantitative constraints on QPE energetics, emission mechanisms, and the mass/energy they recycle into their circumnuclear environments, as well as an observational probe for direct comparison with physical models and hydrodynamical simulations of QPEs.
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All authors Joheen Chakraborty, Erin Kara, Wenbin Lu, Brian D. Metzger, Peter Kosec, Riccardo Arcodia, Itai Linial, Olivia Aspegren, Ehud Behar, Sudip Bhattacharyya, Margherita Giustini, Lorena Hernandez-Garcia, Daniel Kasen, Giovanni Miniutti, Frits Paerels, Erwan Quintin, Claudio Ricci, Daniele Rogantini, Paula Sanchez-Saez, Fatima Zaidouni
Cosmology and Nongalactic Astrophysics
Enhancing Cosmological Constraints from Foreground-Cleaned CMB Maps Using Large-Scale Structure Surveys
Shu-Fan Chen and J. Colin Hill
Extragalactic foregrounds contaminate
cosmic microwave background (CMB) temperature maps at small angular scales and limit their utility for precision cosmology. The internal linear combination (ILC) is a well-known technique for suppressing these contaminants, but residual foreground power remains a limiting factor. Kusiak et al. (2023) proposed adding
galaxy number-density maps as additional ILC channels, exploiting their correlation with the large-scale structure sourcing these foregrounds to suppress contamination. Here we apply this framework to forecast the gains in CMB-based cosmological parameter constraints from near- and next-generation experiments. Using a
halo-model foreground pipeline and a Fisher forecast from joint TT+TE+EE power spectra, we quantify the improvement from
galaxy-tracer-assisted ILC cleaning across three configurations: enhanced Simons Observatory (SO) with unWISE or Rubin-like
galaxy catalogs, and a futuristic CMB-HD configuration with a hypothetical deep
galaxy survey. We find that adding
galaxy tracers reduces the residual foreground power in the cleaned temperature map by $\sim4\%$, $\sim22\%$, and $\sim32\%$ at $\ell\sim10,000$ for the unWISE, Rubin-like, and futuristic samples, respectively. For the overall variance of the cleaned map at $\ell\sim10,000$, it provides $8\%$, $24\%$, and $17\%$ improvements for each combination. The resulting reduction in marginalized parameter error bars is modest for the base six-parameter $\Lambda$CDM model: sub-percent for SO+unWISE, rising to $\sim2\%$ for SO+Rubin-like tracer. Including the effective number of relativistic species $N_{\rm eff}$, we find at most $2.2\%$ improvements for both SO+Rubin-like and CMB-HD+Futuristic tracer. These results establish the expected gains from combining near-term CMB experiments with current and forthcoming large-scale-structure surveys.
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Instrumentation and Methods for Astrophysics
pyEDITH: the coronagraphic exposure time calculator for the Habitable Worlds Observatory
Eleonora Alei, Miles H. Currie, Corey Spohn et al. (+7 more)
To support the development of next-generation missions for the search and characterization of habitable
planets, high-fidelity tools for astrophysical and instrumental noise simulations are needed. In this paper, we introduce pyEDITH, the Python-based coronagraphic exposure time calculator built for the next recommended NASA flagship mission, the Habitable Worlds Observatory (HWO), tasked with searching for signs of habitability and life in dozens of nearby
exoplanet systems. pyEDITH is designed to simulate wavelength-dependent exposure times and signal-to-noise ratios (S/N) for synthetic HWO direct imaging observations, considering realistic engineering specifications and user-defined target information. Its modular architecture ensures flexibility as mission requirements evolve. pyEDITH enables a streamlined integration with modern astronomical workflows and was designed to be used by the scientific community at all skill levels for understanding the capabilities and limitations of different HWO architectures for
exoplanet analyses. The code has been validated against existing exposure time calculators and released open-source on GitHub and Zenodo, as well as made accessible through a Graphical User Interface. The pyEDITH package includes API documentation, tutorial notebooks, and has been used in forthcoming scientific publications.
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All authors Eleonora Alei, Miles H. Currie, Corey Spohn, Christopher C. Stark, Aki Roberge, Avi M. Mandell, Enrico Biancalani, Samantha Gilbert-Janizek, Jacob Lustig-Yaeger, Sarah Steiger
High Energy Astrophysical Phenomena
Reassessing the contribution of long-GRB high-energy afterglows to the isotropic gamma-ray background after GRB 221009A
S.V. Troitsky
Very-high-energy
photons from gamma-ray bursts (GRBs) are absorbed by the extragalactic background light and partly reprocessed into the GeV band. We update previous estimates of the long-GRB contribution to the Fermi-LAT isotropic gamma-ray background (IGRB), using a time-integrated high-energy afterglow template of GRB 221009A, anchored by GeV-TeV data, together with an explicitly specified scaling with
prompt energy and beaming. Despite the observed multi-TeV afterglow, the cascade component reaches only 1.6e-4 of the IGRB. Including direct GeV emission raises the maximum fraction to 1.1e-3, but makes the result more dependent on the population-averaged broadband template. Variations of the extragalactic background light, propagation implementation, intrinsic spectral cutoff, and population prescription do not change the conclusion: the multi-TeV detection of GRB 221009A does not make long GRBs a significant source of the IGRB.
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Astrophysics of Galaxies
Characterising the Globular Cluster Systems of Three Local Group Dwarf Galaxies: NGC6822, NGC147 and NGC185
Gracie McGill, Annette M. N. Ferguson, Dougal Mackey et al. (+8 more)
We present deep HST photometry for 26 globular clusters (GCs) residing in three Local Group dwarf
galaxies: the isolated dwarf irregular (dIrr)
galaxy, NGC6822, and the M31 dwarf elliptical (dE) satellites, NGC147 and NGC185. From their colour-magnitude diagrams (CMDs), we quantify their red giant branch (RGB) and horizontal branch (HB) morphologies, and employ new empirical relationships to derive measurements of
metallicity, reddening and distance. Additionally, we measure sizes and $V$-band magnitudes from their integrated light profiles. We find that the clusters span a range of
metallicities, from [Fe/H] $\sim-0.7$ to $\lesssim-2$; however, the three dwarfs have very similar mean GC
metallicities ($\sim-1.7$ dex) despite their very different evolutionary histories. In contrast, we find that almost all of NGC6822's GCs exhibit red HB morphologies, whereas those in the two dEs are predominantly blue. We highlight three outlying GCs in NGC6822 that have very low
metallicities yet very red HBs; they are also the most extended clusters in our sample, with half-light radii of $\sim 13-17$pc. If these clusters are young, their origin is difficult to explain given their very remote locations, and
metallicities which are significantly lower than those of the old and intermediate-age
stars in NGC6822. These three clusters are strikingly similar to several GCs linked to substructure in the outer
halo of M31, suggesting either the recent
accretion of an NGC6822-like dwarf by M31, or that both M31 and NGC6822 have recently accreted a similar low-mass system. Additionally, we find compelling evidence that another NGC6822 cluster, SC7, is tidally distorted.
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All authors Gracie McGill, Annette M. N. Ferguson, Dougal Mackey, Chiara Crociati, Jess M. Howell, Avon P. Huxor, Mike J. Irwin, Alan W. McConnachie, Alessandro Savino, Nial R. Tanvir, Daniel R. Weisz
Cosmology and Nongalactic Astrophysics
Follow-up of SN 2025wny V: Lens Modelling and Cosmography of a Strongly Lensed Superluminous Supernova at $z = 2.015$ using Space Data
Edvard Mörtsell, Joel Johansson, Ariel Goobar et al. (+12 more)
We present a
lensing and cosmographic analysis of the strongly lensed Type I superluminous
supernova SN 2025wny at
redshift $z=2.015$, multiply imaged by two foreground
galaxies at $z=0.376$. Using imaging obtained with the Hubble Space
Telescope and the James Webb Space
Telescope, we model the lens system with two elliptical power-law mass distributions and an external shear component. In addition to the
supernova image positions, the modelling incorporates the surface-brightness distribution of the lensed host
galaxy. The inferred Einstein radii are $\theta_{\rm E,1}\simeq 1.6$" and $\theta_{\rm E,2}\simeq 0.7$ - $0.8$", with broadly consistent results across all filters. After accounting for microlensing by
stars in the lens
galaxies, the posterior distribution spans total magnifications of approximately $\mu_{\rm tot}\sim 5$–$50$, with flux ratios of the multiple images consistent with observations. Combining the lens models with spectroscopically and photomerically measured time delays yields a filter-marginalized constraint of \[ H_0 = 66.7^{+7.6}_{-6.3}\; {\rm km\,s^{-1}\,Mpc^{-1}}, \] for a fiducial model with isothermal mass profiles. Allowing the density slopes of the lens
galaxies to vary over a broad range results in \[ H_0 = 70.8^{+8.2}_{-6.1}\; {\rm km\,s^{-1}\,Mpc^{-1}}. \] These values are conditional on the adopted parameterization of the lens mass distribution, the assumed priors on the density slopes, and possible additional
lensing contributions from the surrounding large-scale environment. We find that incorporating the currently available stellar kinematic measurements has only a modest effect on the inferred value of $H_0$. Future measurements of the lens-
galaxy kinematics and a detailed characterization of the lens environment will further strengthen the utility of SN 2025wny as a cosmological probe.
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All authors Edvard Mörtsell, Joel Johansson, Ariel Goobar, Alice Townsend, Hannah C.Turner, Suhail Dhawan, Cameron Lemon, Peter Nugent, Thomas E. Collett, Stephen Thorp, Jacob Osman Hjortlund, Jakob Nordin, Lin Yan, Graham P. Smith, Christoffer Fremling
Cosmology and Nongalactic Astrophysics
Follow-up of SN 2025wny IV: Photometric Time-delay Measurements of a Strongly Lensed Superluminous Supernova
Alice Townsend, Suhail Dhawan, Erin E. Hayes et al. (+34 more)
We present photometric time-delay measurements of SN 2025wny, the first strongly lensed Type I superluminous
supernova (SLSN-I), discovered at $z = 2.015$. Time-delay measurements from strongly lensed
supernovae provide an independent probe of cosmology and the Hubble constant, $H_0$, without reliance on the local distance ladder. Using multi-facility imaging data, we performed scene-modelling photometry to deblend four of the lensed images (A-D) and construct $grizJ$-band light curves. We modelled the resolved light curves with Gaussian process regression using GausSN (Hayes et al. 2024) to infer relative time delays and magnifications between the lensed images. We found that a constant magnification model provides a suboptimal description of the data, motivating a time-dependent sigmoid magnification model to account for evolving relative magnification of image A. We measured time delays of $\Delta t_{AB} = -10.6^{+2.2}_{-2.5}$ days and $\Delta t_{AC} = 1.2^{+2.7}_{-2.6}$ days (68% credible intervals), consistent with independent spectroscopic measurements from Johansson et al. (2026). Combining the photometric time delays with the lens model of Mörtsell et al. (2026) gives $H_{0,\:\rm photo} = 80.5^{+26.4}_{-16.7}\;\rm km\,s^{-1}\,Mpc^{-1}$, while including the spectroscopic time delays as well yields $H_{0,\:\rm comb} = 70.8^{+8.2}_{-6.1}\;{\rm km\,s^{-1}\,Mpc^{-1}}$. Our results further demonstrate the potential of strongly lensed
supernovae as independent probes of $H_0$.
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All authors Alice Townsend, Suhail Dhawan, Erin E. Hayes, Maggie L. Li, Joel Johansson, Edvard Mörtsell, Ariel Goobar, Lin Yan, Charlotte Ward, Veena Krishnaraj, Steve Schulze, Jacob Osman Hjortlund, Yu-Jing Qin, Hannah C. Turner, Peter Massey, Jakob Nordin, Jule Augustin, Aleksandra Bochenek, Malte Busmann, Christoffer Fremling, Daniel Gruen, Xander J. Hall, K.-R. Hinds, Ezequiel J. Marchesini, Zoë McGrath, Conor M. B. Omand, Eliana Palazzi, Daniel A. Perley, Andrea Rossi, Killa Santer, Jesper Sollerman, Chiara Ventura, Jacob L. Wise, Tracy X. Chen, Steven L. Groom, Mansi M. Kasliwal, Josiah Purdum