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Physics Astrophysics

astro-ph Watch Astrophysics

Thursday 2 July

Instrumentation and Methods for Astrophysics

Tracing the Boundary of the South Atlantic Anomaly Region with SPHEREx Transient Flagging Rates

Chi H. Nguyen, James Bock, Sean Bryan et al. (+10 more)

The NASA SPHEREx satellite was launched in 03/2025 to survey the full sky between 0.75 - 5.0 um. The image processing of SPHEREx H2RG detectors includes real-time flagging of transient events during integration. SPHEREx follows a polar orbit passing over the South Atlantic Anomaly (SAA) zone multiple times daily, where the transient counts reach as high as >80% of pixels, depleting the pixel inventory for further analysis. The science pipeline flags all exposures taken while in the SAA for re-observation, as well as any with >10% transients regardless of the spacecraft location. After six months, ~1.5% of the exposures outside of the pre-defined SAA zone were flagged. While some exposures are adjacent to the edge of the SAA, the majority appear to trace the geomagnetic field near the poles. Given the importance of the SAA to designing and operating space instruments, in this paper we present the SAA boundary traced by SPHEREx transient flags as a reference for future mission.
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All authors Chi H. Nguyen, James Bock, Sean Bryan, Walter R. Cook, Brendan Crill, C. Darren Dowell, Olivier Doré, Beth Fabinsky, Candice Fazar, Howard Hui, Phillip Korngut, Steve Padin, Michael Zemcov

Instrumentation and Methods for Astrophysics · Cross-listed from physics.optics

Coupling loss and transmission in a multimode fiber-fed virtually imaged phased array (VIPA)

Matthew C. H. Leung, Andrew Szentgyorgyi, Colby Jurgenson et al. (+1 more)

The Virtually Imaged Phased Array (VIPA) is a spectral disperser that has seen increasing adoption across various applications, including optical telecommunications, high-resolution spectroscopy, and LiDAR. Although VIPAs are typically fed by single-mode optical fiber in these applications, there is growing interest in using a multimode optical fiber feed to enable higher throughput. However, a multimode fiber feed introduces several challenges, one of which is a fundamental limit on how much light can be coupled into a VIPA. In this work, we derive a closed-form expression for the minimum tilt angle of a multimode fiber-fed VIPA required for no etendue coupling loss, and we show that this angle depends solely on the input fiber's etendue, the focal ratio of the injection cylindrical lens, and the VIPA's intrinsic parameters. Moreover, we derive the 2D and 3D etendue that can be coupled into a VIPA, as well as the VIPA's etendue coupling efficiency and total transmission, given a particular configuration. We validate our mathematical models using ray-tracing simulations in Zemax OpticStudio non-sequential mode. Our results provide practical guidance for the design of high-throughput optical systems based on multimode fiber-fed VIPAs.
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All authors Matthew C. H. Leung, Andrew Szentgyorgyi, Colby Jurgenson, David Charbonneau

Astrophysics of Galaxies

Satellite quenching by radio jets of central galaxies in galaxy groups

Yijun Wang, Tao Wang, Dingyi Zhao et al. (+9 more)

Feedback from active galactic nuclei (AGN) is now recognized as a key component of galaxy formation models. It plays a central role in regulating the growth and quenching of galaxies in the center of groups. However, the impact of AGN feedback from central galaxies on satellite galaxies remains largely unexplored. Here based on the largest sample to date of radio AGNs in galaxy groups (Yang et al. 2007) and a comprehensive consideration of multiple physical parameters that may influence the star formation of satellite galaxies, we demonstrate that the quiescent satellite fraction around radio AGNs is higher than that around normal galaxies. The most significant enhancement is observed around AGNs with large radio lobes. These findings demonstrate that the impact of kinetic AGN feedback beyond their host galaxies to their satellites. These results provide novel insights into the physical origins of some long-standing puzzles in extragalactic astronomy, including, e.g., galactic conformity and the strong small-scale clustering of quiescent galaxies.
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All authors Yijun Wang, Tao Wang, Dingyi Zhao, Yingjie Peng, Ziwen Zhang, Houjun Mo, Feng Yuan, Zhaozhou Li, Lingyu Wang, Yu Qiu, Yangyao Chen, Ke Xu

Solar and Stellar Astrophysics

The Stellar Observations Network Group (SONG) – A Legacy Archive of Stellar Time-Domain Spectroscopy

M. N. Lund, F. Grundahl, M. S. Fredslund et al. (+41 more)

The Stellar Observations Network Group (SONG) network has operated for more than a decade, providing long-baseline, high-cadence spectroscopic observations of bright stars and the Sun. The observations, from 2014 through 2025, constitute a substantial archive of high-resolution spectra and precise radial velocities for a broad range of time-domain stellar astrophysics. We present an overview of the status, instrumentation, and scientific capabilities of the SONG network, and describe the scope and accessibility of the SONG Data Archive (SODA). We further illustrate the breadth of science enabled by SONG observations, including asteroseismology, stellar variability studies, binary-star characterisation, and exoplanet research. We summarise the operational status and observing strategies of the SONG facilities, describe the available data products and archive infrastructure, and outline procedures for accessing archival observations and proposing new observations within the SONG community framework. The SODA archive currently contains more than 580,000 spectra of 3091 stars obtained with SONG using either iodine-cell or Thorium-Argon wavelength calibration. The archive spans over a decade and includes extensive time-series data for bright targets across a wide range of stellar types and variability classes. Access to the archive is available to members of the SONG community, which remains open to new participants who agree to follow the community policies. The SONG archive has developed into a major long-baseline resource for stellar spectroscopy and radial-velocity time-series analysis. Continued expansion of the archive, together with coordinated observations obtained contemporaneously with TESS and future PLATO observations, is expected to enable new studies of stellar oscillations, variability, and exoplanet host stars through combined radial-velocity and photometric analyses.
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All authors M. N. Lund, F. Grundahl, M. S. Fredslund, P. L. Pallé, S. Simon-Diaz, J. Christensen-Dalsgaard, R. A. Wittenmyer, L. Deng, J. Jackiewicz, H. Kjeldsen, V. Antoci, H. Korhonen, S. H. Albrecht, K. Wang, J. Rudrasingam, R. Handberg, T. R. Bedding, J. L. Rørsted, P. M. Sørensen, D. J. Wright, J. A. Holtzman, J. Klusmeyer, S. Frandsen, E. Weiss, J. Jessen-Hansen, P. Heeren, R. Tronsgaard, T. Arentoft, P. G. Beck, U. G. Jørgensen, A. N. Sørensen, M. I. Andersen, P. Kjærgaard, M. Bizzarro, R. P. Butler, E. Corsaro, R. A. García, D. Stello, S. Murphy, J. Horner, S. Martell, M. J. Martínez González, L. Casagrande, J. Lattanzio

Instrumentation and Methods for Astrophysics

The Habitable Worlds Observatory Technology Development Plan

Matthew Bolcar, Feng Zhao, Paul Scowen et al. (+5 more)

The Habitable Worlds Observatory (HWO) is NASA's next large space telescope, selected by the 2020 Decadal Survey in Astronomy and Astrophysics to search for and characterize habitable exoplanets while enabling a broad range of transformative astrophysics. In August 2024, the HWO Technology Maturation Project Office (TMPO) was formed to begin exploring the HWO science, technology, and mission architectures toward a Mission Concept Review (MCR) at the end of the decade. A primary deliverable of this effort is this technology development plan that identifies critical technologies that enable the mission, defines a process for assessing the readiness of those technologies, and outlines a strategy for developing those technologies to a Technology Readiness Level (TRL) of 5 before the MCR. This document covers technologies organized along three tracks: Coronagraph System technologies, Ultra-stable Telescope System technologies, and High-sensitivity Ultraviolet and Visible Instrumentation technologies. Additional emerging and enhancing technologies are also discussed.
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All authors Matthew Bolcar, Feng Zhao, Paul Scowen, Lee Feinberg, Breann Sitarski, Alice Liu, J. Scott Smith, Josh Abel

Astrophysics of Galaxies

Small-scale dynamo saturation across magnetic Prandtl numbers using the EDQNM closure

Muhammed Irshad, Kandaswamy Subramanian and Pallavi Bhat

Small-scale dynamos (SSDs) are believed to be the primary source of magnetic fields in all turbulent astrophysical systems, especially those with weak rotation such as elliptical galaxies and galaxy clusters. The initial kinematic phase of these dynamos is relatively well understood. Here we demonstrate analytically and numerically that, in an appropriate limit, the eddy-damped quasi-normal Markovian (EDQNM) closure for incompressible magnetohydrodynamic turbulence is strictly equivalent to the earlier models of kinematic dynamos. Moreover, it allows the extension of the kinematic dynamo framework to multi-scale turbulent flows and into the nonlinear regime. The EDQNM closure also enables us to explore a wide parameter range which is inaccessible to direct numerical simulations of the SSD. Using nonhelical EDQNM simulations, we identify several asymptotic regimes of nonlinear dynamo action when the system is highly turbulent with fluid Reynolds number $Re \gtrsim 10^6$ for magnetic Prandtl number $Pm > 1$ and magnetic Reynolds number $Rm \gtrsim 10^6$ for $Pm < 1$: 1) the kinematic growth rate approaches a value independent of $Pm$, 2) the saturated magnetic to kinetic energy ratio similarly converges to $\simeq 0.55$ across $Pm$, while the ratio of magnetic to kinetic integral wavenumbers asymptotes to $\simeq 3$. For all $Pm$, we further find strong feedback between magnetic field and velocity field largely via Alfvénisation leading to a saturated kinetic and magnetic spectra with almost the same inertial range with a slope of $-3/2$. These findings could provide guidance for future global simulations and for modeling the nonlinear regime of astrophysical systems living in these extreme limits.
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Solar and Stellar Astrophysics

Unveiling the properties of pulsating low-mass helium-core white dwarfs through TESS asteroseismology I. First results

Leila M. Calcaferro, Nikoo Hosseininezhad, Murat Uzundag et al. (+4 more)

Recent space-based photometry, particularly from TESS, has opened new possibilities for probing the internal structure of low-mass (LM) helium (He)-core white dwarfs (WDs). We present a homogeneous asteroseismological analysis of six pulsating LM WD stars, based on new and updated TESS photometry. We processed short- and ultra-short-cadence TESS observations of TIC 290904838 (J1112), TIC 156064657, TIC 33717565, TIC 344130696, TIC 72637474, and TIC 188087204, and analyzed the resulting pulsation spectra. We then carried out a detailed asteroseismological analysis using fully evolutionary models of LM He-core WDs that allow for varying hydrogen (H)-envelope thicknesses. We also estimated spectroscopic/photometric stellar masses when atmospheric parameters are available. We report the first TESS-based frequencies for J1112 and provide revised or expanded frequency solutions for the remaining targets. The asteroseismological analysis yields relatively well-constrained solutions for three stars, a representative but more tentative solution for one target, and constrained ranges for the remaining two. The inferred solutions span a broad range of H-envelope thicknesses, although some of the asteroseismological inferences remain tentative because of the limited number of observed periods available for the analysis. For most objects, the derived spectroscopic/photometric stellar masses are broadly compatible with the asteroseismological values. This is the first homogeneous TESS-based asteroseismological study of a small sample of pulsating LM WDs. Our results suggest that LM WDs can harbor H envelopes with a range of thicknesses, from canonical (thick) to very thin, as in average-mass H-rich pulsating WDs. They also provide a useful reference point for future studies of larger samples, which will hopefully benefit from richer mode sets and improved mode identification.
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All authors Leila M. Calcaferro, Nikoo Hosseininezhad, Murat Uzundag, Alejandro H. Córsico, Keaton J. Bell, Leandro G. Althaus, J.J. Hermes

Solar and Stellar Astrophysics · Cross-listed from physics.space-ph

Evolution and Impact of Switchbacks Throughout the Heliosphere

Alfred Mallet, Chen Shi, Anna Tenerani et al. (+23 more)

Magnetic switchbacks are large-amplitude fluctuations in the interplanetary magnetic field, and appear frequently in the near-Sun solar wind explored recently by Parker Solar Probe: these new observations have prompted many new studies into their properties and origins. Here, we first review what is known about how switchbacks evolve as they travel away from the Sun: both in terms of their expansion-driven growth and their decay due to various processes like turbulence, reconnection, dispersion, parametric instability, and interaction with interplanetary shocks. We then review the current state of knowledge on how switchbacks impact the physics of the solar wind as a whole: in terms of the turbulent cascade, acceleration and heating of the wind, modification of the open solar flux and scattering of energetic particles. Finally, we suggest future studies to further our understanding of switchback evolution and impacts on the heliosphere.
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All authors Alfred Mallet, Chen Shi, Anna Tenerani, Oleksiy Agapitov, Mojtaba Akhavan-Tafti, Samuel Badman, Nina Bizien, Trevor Bowen, Mihir I. Desai, J.F. Drake, Timothy Horbury, Andrea Larosa, Maria S. Madjarska, Francesco Malara, Lorenzo Matteini, Mathew Owens, Victor Réville, Nikos Sioulas, Shirsh Lata Soni, Jonathan Squire, Gabriel Ho Hin Suen, Marc Swisdak, Marco Velli, Jaye Verniero, Nicholas Watkins, Luca Sorriso-Valvo

Cosmology and Nongalactic Astrophysics

S-PLUS Clusters And Large-scale Environments (SCALE): II. PZWav versus redMaPPer identification of eRosita groups

L. Doubrawa, A. Finoguenov, E. S. Cypriano et al. (+10 more)

We present the construction and characterization of a multi-wavelength catalog of galaxy groups and clusters by matching optical detections from the Southern Photometric Local Universe Survey (S-PLUS) with extended X-ray emission from the first eROSITA all-sky survey data release (eRASS1). We employ a probabilistic matching framework, based on the modified Hausdorff distance, to associate galaxy systems identified by the PZWav cluster finder and characterized by the AME membership estimator with X-ray surface brightness contours. This method explicitly accounts for the photometric redshift probability distribution of galaxies and allows us to explore the critical trade-off between catalog completeness and purity. We investigate how the matched sample changes with different optical selection depths, defined by absolute magnitude cuts of $M_r$ < -18.5, -19, -19.5, and -20 sampling redshifts within 0.08 < z < 0.25, and across purity levels of 80%, 90%, and 95%. We find that fainter optical cuts enhance the recovery of low-mass, low-luminosity groups, while brighter cuts favor more massive clusters and increase the effective survey volume at higher redshifts. Stricter purity requirements reduce contamination but systematically lower completeness, particularly for low-luminosity systems. The derived X-ray luminosity functions agree well with previous determinations, and the logN-logS distributions confirm the high recovery rate of luminous clusters. Comparisons with the redMaPPer cluster catalog validate our approach, showing consistent trends and significant overlap, while our method offers improved completeness at the group scale. This work demonstrates a robust, flexible methodology for creating reliable multi-wavelength cluster catalogs, essential for cosmological studies and investigations of galaxy evolution in dense environments.
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All authors L. Doubrawa, A. Finoguenov, E. S. Cypriano, C. Mendes de Oliveira, E. V. Lima, L. Nakazono, G. Souza, J. Comparat, A. Gonzalez, R. Demarco, A. Kanaan, T. Ribeiro, W. Schoenell

Cosmology and Nongalactic Astrophysics

S-PLUS Clusters And Large-scale Environments (SCALE): I. A catalog of known clusters and groups in DR5 and a pilot study of Abell 4038

C. Mendes de Oliveira, N. M. Cardoso, P. A. A. Lopes et al. (+26 more)

Within the framework of the Southern Photometric Local Universe Survey (S-PLUS), we introduce ${\bf S}$-PLUS ${\bf C}$lusters ${\bf A}$nd ${\bf L}$arge-scale ${\bf E}$nvironments (SCALE), a project dedicated to the study of galaxy clusters, groups, and their environments using 12-band photometry of S-PLUS combined with spectroscopic and photometric data from the literature. In this first paper, we present a catalog of 83 previously known systems in the redshift range $0.008 \leq z_{\rm spec} \leq 0.1$, for which we derive $R_{200}$, $M_{200}$, and velocity dispersions. Spectroscopic members are selected and matched with S-PLUS photometric redshifts (photo-$z$s). We find very good agreement between literature spectroscopic redshifts (spec-$z$s) and S-PLUS photometric redshifts (photo-$z$s), demonstrating the potential of the latter for cluster and group membership determination. As a proof of concept, we obtain photometric memberships for Abell 4038 using the Reliable Photometric Membership technique. A two- and three-dimensional analysis of the region within $10 h^{-1}$ Mpc ($10\times R_{200}$) from the center of Abell 4038 reveals about a dozen substructures including two additional clusters within $1.3\times R_{200}$ (Abell 4038B and Abell 4049). A color-luminosity segregation analysis shows that more luminous (less luminous) galaxies are redder (bluer), as expected. Low-concentration galaxies ($C \leq 2.5$) exhibit a weaker color-luminosity dependence, compared to higher-concentration ones, indicating mass-dependent evolutionary pathways that challenge a simple morphology-color dichotomy, with low-luminosity galaxies presenting bluer colors largely independent of concentration. The SCALE catalog provides a valuable basis for future studies of large-scale structures and their connection to galaxy evolution.
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All authors C. Mendes de Oliveira, N. M. Cardoso, P. A. A. Lopes, A. L. B. Ribeiro, D. E. Olave-Rojas, A. Krabbe, L. Sodré Jr., R. Demarco, A. V. Smith Castelli, R. Cid Fernandes, F. R. Herpich, S. Torres-Flores, E. R. Carrasco, E. V. R. Lima, G. Oliveira Schwarz, A. P. Costa, L. Doubrawa, G. P. Montaguth, C. Lima-Dias, E. S. Cypriano, M. S. Carvalho, C. Lobo, M. Fonseca-Faria, L. Nakazono, A. R. Lopes, F. Almeida-Fernandes, A. Kanaan, T. Ribeiro, W. Schoenell

Earth and Planetary Astrophysics

Multistage Rocket Optimization, Geophysics, and the Spacefaring Envelope of Habitable Super-Earths

Sanjoy M. Som

Habitability is typically defined by whether a planet can support life, rather than whether it can support a technological civilization capable of escaping its gravity well. We introduce spacefaring capability as a technological axis of habitability, defined by the ability to place a 1000 kg payload on an escape trajectory using chemical propulsion. We develop a coupled geophysical–atmospheric–astronautical model that maps this “spacefaring envelope” as a function of planetary mass and surface pressure. Building on Hippke (2018) and Gonzalez (2020), we optimize multistage chemical rockets by minimizing the reliability-weighted expected launch mass while determining the optimal stage count, first-stage engine number, and mission reliability. Assuming F-1-class first-stage engines, the model reproduces the Saturn V gross lift-off mass to within $\sim\!30\%$ and the F-1 turbopump power to within $\sim\!18\%$. Over $0.1$–$10$~bar, atmospheric pressure changes the required launch mass by up to $\sim\!35\%$ on $0.5\,M_\oplus$ planets, where drag contributes substantially to the ascent $\Delta v$, but by only a few percent for $M_\oplus \gtrsim 4$. Gravity, rather than atmospheric drag, therefore sets the primary limit on chemical escape from super-Earths. Imposing a post-optimization limit of $\sim\!100$ F-1-class first-stage engines renders escape of the benchmark payload impractical above $\sim\!11.5\,M_\oplus$. This engine-counting constraint independently corroborates the $\sim\!10\,M_\oplus$ limit derived by Hippke (2018) from an engine-independent fuel-ratio argument. These results provide a physically motivated framework for assessing whether rocky exoplanets are capable of supporting technological civilizations that can escape their planetary gravity wells.
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Earth and Planetary Astrophysics

The Longest-period Young Transiting Exoplanets. A Duo of Puffy Giants inside a Debris Disk

Carlos del Burgo, Alejandro Suárez Mascareño, Ana Heras Pastor et al. (+35 more)

We identify two large-radius planets around the F-type star HD 114082 as the longest-period young transiting exoplanets known. From the first transit, detected by NASA's Transiting Exoplanet Survey Satellite (TESS), and a second dip, spotted by the Next-Generation Transit Survey (NGTS), we predicted mid-transit times for HD 114082 b (planet b). We pinpoint its orbit (period Pb= 225.5504$\pm$0.0004 days) from a third transit captured with the ESA's CHaracterising ExOplanet Satellite and the upgraded Antarctic Search for Transiting ExoPlanets telescope (ASTEP+), alongside orbit-discriminating observations. Another dimming partly covered by ASTEP+ completes the four-transit series. We support with dynamical evidence the planetary nature of a deeper transit detected with TESS and NGTS, identifying planet c. Additionally, we reexamine the debris disk, fitting its excess emission with two dust components. Fundamental stellar parameters are inferred from stellar evolution models, while a joint modeling of photometric and radial-velocity time series yields the planetary parameters, with masses further constrained using an N-body code. For planet b, the semimajor axis a$_b$= 0.791$\pm$0.008 au, eccentricity eb$\approx$ 0, inclination ib= 89.791$\pm$0.014 degrees, radius Rb= 1.046$\pm$0.014 R$_J$, and 95 % confidence upper limit on its mass M$_{95\%,b}$= 1.6 M$_J$. For planet c, a$_c$= 0.99$^{+0.03}_{-0.04}$ au, ec$\approx$ 0, i$_c$= 89.701$\pm$0.011 degrees, R$_c$= 1.36$\pm$0.03 R$_J$, and M$_{95\%,c}$= 2.0 M$_J$ (0.24 M$_J$ if adding transit timing variation constrains). They seem to be moderate-to-low-mass giants in nearly resonant, coplanar, circular orbits that formed in situ, or beyond the snowline, and migrated inwards, shaping the disk.
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All authors Carlos del Burgo, Alejandro Suárez Mascareño, Ana Heras Pastor, Jonathan P. Marshall, Peter J. Wheatley, Edward M. Bryant, Samuel Gill, Jorge Fernández Fernández, David R. Anderson, Matthew P. Battley, Edward Gillen, Solène Ulmer-Moll, James McCormac, Monika Lendl, Ioannis Apergis, Faith Hawthorn, James S. Jenkins, Maximiliano Moyano, Louise D. Nielsen, Alexis M. S. Smith, Suman Saha, Stéphane Udry, Jose I. Vines, Richard G. West, Daniel Bayliss, Hugh P. Osborn, Tristan Guillot, Amaury H. M. J. Triaud, Olga Suarez, Matteo Beltrame, Abdelkrim Agabi, Isabella Pagano, Matthew J. Hooton, Matthew R. Burleigh, Lyu Abe, Philippe Bendjoya, Georgina Dransfield, Djamel Mékarnia

Earth and Planetary Astrophysics

On the Eccentricity Distribution and Tidal Evolution of Transiting Brown Dwarfs

Thiago Ferreira and Malena Rice

Brown dwarfs on short-period orbits populate an intermediate regime between hot Jupiters and tight stellar binaries, lying at the intersection of possible evolutionary avenues. Their orbital eccentricities retain the dynamical imprint of both their formation pathways and any subsequent tidal evolution, providing a diagnostic for whether such objects formed in situ at small separations or were driven inward from higher-eccentricity orbits shaped by tidal dissipation. Using a hierarchical Bayesian framework, we characterise the orbital eccentricity distribution of transiting brown dwarfs. Short-period brown dwarfs ($P < 16$ days) are well represented by a Beta distribution with $\alpha < 1$ and $\beta > 1$, indicating a population concentrated at low eccentricities, whereas longer-period brown dwarfs ($P \geq 16$ days) display $\alpha,~\beta > 1$ and therefore occupy a more dynamically excited regime. This difference in eccentricity distributions likely reflects corresponding differences in the populations' eccentricity-damping timescales: close-in systems may evolve toward circular orbits on relatively short timescales, whilst wider companions experience negligible tidal processing over their lifetimes. Assuming that the full set of transiting brown dwarfs stems from a single primordial eccentricity distribution, {we constrain the typical brown dwarf tidal quality factor to $\mathcal{Q}_{\rm BD} = 10^{8.1\pm1.0}$ when neglecting the influence of tides raised on the host star, or $\mathcal{Q}_{\rm BD} = 10^{7.1\pm0.3}$ and $\mathcal{Q}_{\star} = 10^{6.0\pm0.1}$ when they are included.
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Earth and Planetary Astrophysics

Detection and identification of asteroids with the 4-m ILMT

Sara Filali, Bhavya Ailawadhi, Talat Akhunov et al. (+11 more)

The International Liquid Mirror Telescope (ILMT) covers a 22.3' wide strip of sky in declination ({\delta}), centred at {\delta} = +29{\deg} 21' 41.4” and right ascension ({\alpha}) in the range 0 h <= {\alpha} < 24 h. Having a short focal length (f /D ~ 2.4) and a large diameter (4 m), makes the ILMT an excellent asteroid hunter. The ILMT began its 4th cycle in October 2024, running through May 2025. The astrometric accuracy has been improved to 0.1” , and the PyLMT - a detection and classification pipeline -, has been fine-tuned using data from previous cycles. The current detection rate is tens of transients detected each night with high accuracy in classification and identification. We present statistical results for the asteroids detected during ILMT's Cycles 1-4. We first evaluate the astrometric performance of the detections across different ecliptic latitude ranges. We then describe the positions, apparent motions, and V magnitudes predicted by the Minor Planet Center (MPC) for the asteroids observed in the SDSS g', r', and i' bands. Finally, we assess the ILMT's potential for detecting near-Earth objects (NEOs), potentially hazardous asteroids (PHAs), and comets.
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All authors Sara Filali, Bhavya Ailawadhi, Talat Akhunov, Monalisa Dubey, Naveen Dukiya, Paul Hickson6, Priyanshi Kumari, Gokul Singh Mehra, Kuntal Misra, Vibhore Negi, Anna Pospieszalska-surdej, Kumar Pranshu, Jean Surdej, Sarvesh Kumar Yadav

Astrophysics of Galaxies

The MIRI Early Obscured-AGN Wide Survey (MEOW): A Population of Hidden AGN at $z \gtrsim 5$ Revealed by JWST/MIRI Imaging

Gene C. K. Leung, Anna-Christina Eilers, Ryan Endsley et al. (+25 more)

We present the MIRI Early Obscured-AGN Wide Survey (MEOW), a JWST/MIRI imaging survey designed to detect dust-obscured active galactic nuclei (AGN) across cosmic time, with a particular focus on the high-redshift universe at $z \gtrsim 5$. MEOW observes the GOODS-N and GOODS-S fields with 43 pointings covering 95 arcmin$^2$ with the F1000W and F2100W filters, reaching depths of 0.5 and 3.6 $\mu$Jy ($5\sigma$), respectively. Using spectral energy distribution (SED) modeling combining MEOW photometry with archival HST, JWST/NIRCam, and SCUBA-2 data, we identify a sample of 16 MIRI-selected AGN at $z = 4.5$–$7.2$ (12 spectroscopically confirmed), spanning bolometric luminosities of $L_{\rm bol} = 10^{44.6}$–$10^{46.4}$~erg~s$^{-1}$. Twelve of the 16 AGN are newly identified in this work, including at least five narrow-line AGN representing the obscured population to which broad-line spectroscopic searches are insensitive. Two broad-line AGN exhibit markedly different mid-infrared emission properties, consistent with one being a little red dot (LRD) and the other either a typical AGN or an LRD with unusually strong hot-dust emission. The MIRI-selected AGN bolometric luminosity function at $z = 4.5$–$6$ yields number densities comparable to those of broad-line AGN and LRDs, suggesting that obscured AGN contribute significantly to the total AGN census at these epochs. The narrow-line AGN reside in diverse host environments, with evidence for both circumnuclear and host-galaxy-scale obscuration, pointing to multiple physical mechanisms at work. These results establish JWST/MIRI imaging as an indispensable component of a multi-faceted approach to a complete census of early supermassive black hole growth.
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All authors Gene C. K. Leung, Anna-Christina Eilers, Ryan Endsley, Steven L. Finkelstein, Micaela B. Bagley, Guillermo Barro, Anton M. Koekemoer, Pablo G. Pérez-González, Nor Pirzkal, Bren E. Backhaus, Teodora-Elena Bulichi, Jaclyn B. Champagne, Katherine Chworowsky, Nikko J. Cleri, Mark Dickinson, Xiaohui Fan, Seiji Fujimoto, Norman A. Grogin, Allison Kirkpatrick, Dale D. Kocevski, Vasily Kokorev, Rebecca L. Larson, Ray A. Lucas, Fabio Pacucci, Casey Papovich, Anthony J. Taylor, Natalia C. Villanueva, Guang Yang

Astrophysics of Galaxies

Helical radio jets as probes of magnetised cluster environments: Periodic Faraday Rotation Revealed in the Corkscrew Galaxy by POSSUM

Sarah N. Bradbury, C. S. Anderson, N. M. McClure-Griffiths et al. (+14 more)

Jets from active galactic nuclei (AGN) that exhibit regular plane-of-sky oscillations may provide a probe of magnetised plasma within the jets and their local intracluster medium (ICM). If such morphologies trace three-dimensional helices, path length differences between near and far sides of the flow might imprint quasi-periodic signatures in Faraday rotation. We present ASKAP Band 2 (1296-1440 MHz) polarimetric observations of a helical-tailed radio galaxy (the "Corkscrew Galaxy") from early science data from the POlarisation Sky Survey of the Universe's Magnetism (POSSUM), and test whether its quasi-periodic morphology produces signatures in Faraday rotation. We detect significant RM oscillations with a spatial period of (342 +/- 101) arcsec, consistent within the Rayleigh resolution limit with the jet's lateral deviations ((290 +/- 72) arcsec). Cross-correlation analysis reveals systematic variation along the jet: the eastern section shows alignment between jet deviation and RM, consistent with a jet-associated or sheath-like Faraday screen, while the western section exhibits a phase shift, indicating a transition in the dominant Faraday-rotating medium and possible contribution from the local ICM. These results demonstrate that quasi-periodic RM signatures can disentangle the dominant Faraday-rotating medium in AGN jets, and show that in some embedded radio galaxies the dominant RM contribution arises near the source rather than the cluster foreground. We also outline reliability criteria required to avoid false positive detections and inadequate sampling. Helical jet structures therefore show strong promise as probes of magnetised cluster environments, a capability that will expand in the SKA era.
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All authors Sarah N. Bradbury, C. S. Anderson, N. M. McClure-Griffiths, Y. K. Ma, A. J. M. Thomson, L. Rudnick, S. P. O'Sullivan, B. M. Gaensler, B. S. Koribalski, E. L. Alexander, Takuya Akahori, L. Baidoo, E. Carretti, G. Heald, H. Sakemi, T. Vernstrom, J. West

Cosmology and Nongalactic Astrophysics

Limits on global cosmic birefringence using radio sources

Richard A. Battye, Neal Jackson and Ian Browne

We have made measurements of the difference between the position angle (PA) on the sky and the polarization position angle (PPA) of radio sources using data from a combination of the Radio Fundamental Catalogue (RFC) across a range of frequencies between 2.7 and 15~GHz and Cosmic Lens All Sky Survey (CLASS) which observes polarization at 8.4~GHz (X-band). For the 2111 sources with jet PAs measured in the X-band and a known redshift, the distribution is peaked at $\approx 0^{\circ}$ as expected for no birefringence and it can be modelled by two populations: one which is a Gaussian with mean $\mu_{\beta}=(0.2\pm 1.0)^{\circ}$ and standard deviation $\sigma_{\beta}=(14.7\pm 1.1)^{\circ}$ and the other a uniform distribution of sources which are a fraction $f_\beta=0.72\pm 0.02$ of the total. Uncertainties in $\mu_\beta$ can be reduced to $\approx 0.6^{\circ}$ by stacking measurements of the PA from other wavebands. We find that limits of $\approx 0.1^{\circ}$ might be possible with a sample of $\sim 10^5$ similarly selected sources and that this could provide a confirmation of recent claims of global birefringence made using the Cosmic Microwave Background observations from the Planck satellite.
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Astrophysics of Galaxies

Polar coordinate transformations for machine learning based dark matter subhalo detection in strong gravitational lenses

Jacob M Campbell, Simon Dye, Emma Chapman et al. (+1 more)

Strong gravitational lensing provides a powerful probe of dark matter, particularly on small scales where the gravitational effects of dark matter subhalos within galaxies can manifest as perturbations within the extended arcs of gravitationally lensed sources. We investigate whether transforming lensed images into polar coordinates improves the ability of convolutional neural networks to infer subhalo mass. We introduce a machine learning architecture that outputs a prediction uncertainty alongside a mass prediction to enable assessment of network reliability. Using simulated Hubble Space Telescope observations, we compare our models trained on Cartesian and polar representations under different initialisation schemes, noise levels, and subhalo concentrations ($c=60$, $c=30$). We find that polar-transformed inputs consistently yield higher subhalo detection fractions than standard Cartesian images across all tested masses. For subhalos with mass $10^9M_\odot \leq M \leq 10^{9.5}M_\odot$, the fraction of subhalos the network is able to detect increases by $\sim 15$ per cent. Pretrained networks outperform randomly initialized networks, and the polar transform consistently improves network performance in both low signal-to-noise data and for lower-concentration subhalos. The relative improvement is highest in regimes where subhalo perturbations are most difficult to detect, such as low signal-to-noise data or systems containing low concentration subhalos. These results demonstrate that presenting strong lensing images in a polar representaion provides a computationally inexpensive way of improving CNN-based subhalo detection.
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All authors Jacob M Campbell, Simon Dye, Emma Chapman, Adam Moss

Instrumentation and Methods for Astrophysics

Astrometric Calibration of the 4-m International Liquid Mirror Telescope Observations

Vibhore Negi, Naveen Dukiya, Gokul Singh Mehra et al. (+12 more)

The 4-m International Liquid Mirror Telescope (ILMT) is a dedicated time domain survey telescope that continuously scans the zenithal sky over the Indian Himalayas in the g', r' and i' optical bands. Its unique capability to repeatedly image the same strip of sky every night makes it a highly useful instrument for the photometric and astrometric studies of Solar System, Galactic and extragalactic objects. We present a robust astrometric calibration pipeline developed for the ILMT data obtained in the time delay integration (TDI) mode. The pipeline uses a linear transformation model from pixel to world coordinates, with a second order correction for the asymmetric optical distortions introduced by the telescope's optical corrector, and ties the astrometric solution to the Gaia DR3 reference frame. The pipeline is integrated to the routine ILMT data processing workflow. Using data from the first four observing cycles (2022-2025), we present the first assessment of the astrometric performance of the pipeline based on positional residuals of sources cross-matched with Gaia DR3. The pipeline achieves a typical astrometric precision of ~100 milliarcseconds (mas), reaching ~70-80 mas for moderately bright sources (G~16.5-18.5). These results, based on 347 nights of data, demonstrate the stability and reliability of ILMT astrometry over multi-year timescales. The astrometrically calibrated data from these four observing cycles have been made publicly available to the astronomical community. This work establishes a validated framework for precision astrometry with zenith-pointing TDI surveys and provides a foundation for future time-domain studies with ILMT, including variability characterization, transient localization, and long-term positional monitoring.
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All authors Vibhore Negi, Naveen Dukiya, Gokul Singh Mehra, Bhavya Ailawadhi, Monalisa Dubey, Sara Filali, Paul Hickson, Brajesh Kumar, Priyanshi Kumari, Sapna Mishra, Kuntal Misra, Bikram Pradhan, Kumar Pranshu, Jean Surdej, Sarvesh Kumar Yadav

Earth and Planetary Astrophysics

Azimuthal brightness modulation reveals hidden rings in CI Tau

C. E. Scardoni, G. P. Rosotti, F. Zagaria et al. (+4 more)

Protoplanetary disks often host substructures such as rings and gaps, which trace key processes in planet formation and dust evolution. However, narrow rings may remain unresolved due to limited observational resolution, hiding critical information about early planetesimal formation and the amount of dust present. We apply the azimuthal brightness modulation method, based on the modulation produced by multiple unresolved optically thick rings embedded in an optically thin background Scardoni+2024, to multi-wavelength ALMA observations of CI Tau to identify unresolved rings and constrain their geometry and optical depth. We analysed CI Tau archival ALMA continuum observations in bands 3, 6, and 7, extracting azimuthal brightness profiles along narrow annuli and comparing them with forward modeled synthetic observations of inclined disks containing unresolved rings. We detect the azimuthal signature at $\sim22$ au in all three bands, consistent with unresolved, optically thick rings embedded in a lower optical depth background. Multi wavelength modelling constrains the rings' geometry and optical depth, consistent with conditions expected for streaming instability and early planetesimal formation. Our results demonstrate the applicability of this azimuthal signature technique to real disks, reveal fine scale dust substructures in CI Tau, and illustrate a new method to study the early stages of planet formation below the nominal resolution limit.
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All authors C. E. Scardoni, G. P. Rosotti, F. Zagaria, A. Ribas, M. Villenave, C. J. Clarke, R. A. Booth

High Energy Astrophysical Phenomena

Non-thermal emission in jets and winds: Expected emission and spectral index distributions

M. Meenakshi, D. Mukherjee, G. Bodo et al. (+5 more)

The origin of synchrotron emission in compact radio sources associated with active galactic nuclei (AGN) remains poorly understood. In a series of papers, we have examined diagnostic tools to disentangle the dominant underlying processes. In this study, we investigate the in situ evolution of cosmic-ray electrons (CREs) in compact AGN jets and winds, and examine how their evolution shapes the resulting observable radio properties. In jets, CREs experience multiple shock interactions as they propagate along the spine toward the hotspot and flow into the cocoon via backflows. In winds, CREs are predominantly accelerated at the Mach disc, with occasional re-acceleration within turbulent cocoon backflows. The continuous mixing of different CRE populations within the cocoon produces observational signatures that cannot be inferred from instantaneous conditions alone. In all jet simulations, spectral indices are flattest near the hotspot and steepen progressively away from the hotspots. In winds, spectra steepen with increasing distance from the Mach disc, with this trend becoming more pronounced at high radio frequencies due to radiative losses. We find the Mach disc to be a significantly more efficient CRE acceleration site than the forward shock in winds, which weakens as the wind expands to large scales. Since morphology, especially at low resolution, can be ambiguous for compact sources, spatially resolved spectral indices, particularly when combined with emission and polarization signatures, can provide a powerful diagnostic.
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All authors M. Meenakshi, D. Mukherjee, G. Bodo, P. Rossi, C. M. Harrison, L. K. Morabito, P. Kharb, S. Silpa

Astrophysics of Galaxies

The largest sample of AGN outflows in dwarf galaxies using DESI DR1

V. Rodríguez Morales, M. Mezcua, Ragadeepika Pucha et al. (+40 more)

In the last decade, the presence of active galactic nuclei (AGN) outflows and feedback in dwarf galaxies ($\mathrm{M_\ast}$<$10^{10}\mathrm{M}_\odot$) has gained ground over supernova (SN) feedback as the main mechanism regulating star formation. In this work, we perform the first systematic search for AGN outflows in dwarf galaxies using the Dark Energy Spectroscopic Instrument Data Release 1 (DESI DR1). From $\sim$ 7 million galaxies at z$<$0.45, we identify ionized outflows through the detection of broad components in the [OIII]$\lambda5007$Åemission line. Galaxies are divided into dwarf and massive systems. Then, using emission-line diagnostic diagrams, we classify as star forming or AGN. We identify 1,502 AGN dwarf galaxies with outflow signatures. Comparing the distributions of star forming and AGN galaxies with outflows, we find that, among the 1,502 AGN dwarf galaxies with outflow signatures, AGN are the most likely drivers of the observed outflows in $\sim$83$\%$ of those with W$_{80}$ velocity $>250$ km s$^{-1}$. This constitutes the largest statistical sample of AGN outflows in dwarf galaxies to date. In massive galaxies, AGN dominance occurs above W$_{80}>350$ km s$^{-1}$. Therefore, two new velocity thresholds are proposed for identifying AGN-driven outflows in dwarf and massive galaxies. Besides, we find that outflows in dwarf galaxies are more likely to escape the dark matter halo than those in massive galaxies, allowing gas to be redistributed from the inner to the outer regions. This suggests that AGN outflows may have a major impact on dwarf galaxies.
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All authors V. Rodríguez Morales, M. Mezcua, Ragadeepika Pucha, C. Circosta, S. Juneau, M. Siudek, S. Panda, J. Aguilar, S. Ahlen, D. Bianchi, D. Brooks, T. Claybaugh, A. Cuceu, A. de la Macorra, B. Dey, P. Doel, J.E. Forero-Romero, S. Gontcho A Gontcho, G. Gutierrez, J. Guy, C. Hahn, R. Joyce, A. Kremin, A. Lambert, M. Landriau, L. Le Guillou, M. Manera, P. Martini, A. Meisner, R. Miquel, J. Moustakas, W.J. Percival, C. Poppett, F. Prada, I. Pérez-Ràfols, G. Rossi, E. Sanchez, D. Schlegel, M. Schubnell, D. Sprayberry, G. Tarlé, B.A. Weaver, H. Zoo

Cosmology and Nongalactic Astrophysics

The youth of the intracluster medium. I. A non-parametric characterisation of the gas and electron number density profiles of $z \simeq 2$ protoclusters

David Vallés-Pérez, Annalisa Bonafede, Klaus Dolag et al. (+3 more)

Context. Protoclusters of galaxies are the earliest phase in the assembly of galaxy clusters and can provide invaluable information about plasma physics, cosmic magnetism, and cosmology. However, due to small angular sizes and cosmological dimming, observing the proto-intracluster medium (proto-ICM) associated with protocluster cores is far from trivial. Aims. We aim to provide a non-parametric description of the gas mass and electron number density profiles of the proto-ICM at $z = 2$, and to study their dependence on mass, dynamical state and central activity. Methods. We extract and analyse over $3800$ regions around protocluster cores with spherical-overdensity masses above $M_\mathrm{500c} > 10^{13} \, M_\odot$ out of a large simulated volume within the Magneticum suite. We study their density profiles, temperature structure, ionisation degree and electron number density as a function of mass and other secondary properties characterising dynamical state and central activity, extending from the central halo to the surrounding protocluster environment. Results. Protoclusters present moderate deviations from self-similarity in their density profiles and temperature structure, with a strong double-$\beta$ structure especially relevant at high masses and intense AGN accretion. Hot, ionised gas is only dominant at intermediate radii ($r \gtrsim [0.1-0.5] R_\mathrm{500c}$), where its density also correlates with mass and dynamical disturbance. Conclusions. These results constitute the basis for a forthcoming parametric calibration of proto-ICM density profiles, which could be useful for interpreting observables sensitive to the density and ionisation of the diffuse gas.
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All authors David Vallés-Pérez, Annalisa Bonafede, Klaus Dolag, Marco Balboni, Paolo Tozzi, Marika Lepore

Earth and Planetary Astrophysics

Contribution of White Dwarf Formation Kicks to the Free-Floating Planet Population

Alexander P. Stephan and Keivan G. Stassun

Free-Floating Planets (FFPs) are a distinct class of exoplanets that do not orbit stars but are nevertheless found to be very common. A variety of formation mechanisms have been proposed as their origin, such as "star-like" direct collapse from gas and dust clouds or ejection from young planetary systems via dynamical instabilities. Here, another possible formation scenario is explored that would instead apply for old planetary systems, in the form of White Dwarf (WD) formation kicks. Observations over recent years have shown that WDs experience a mild recoil kick during their formation from Asymptotic Giant Branch (AGB) stars. Here we show that, while WD formation kicks directly unbind only $\sim1\%$ of the known planet and exoplanet population, they drive dynamical instabilities in $\gtrsim40\%$ of known long-period multi-planet systems, likely leading to planet ejection and FFP generation by most WDs. We also show that FFPs generated via WD kicks will have undergone potentially significant and long-lasting heating via their host stars' enhanced AGB luminosities. Given the low ejection velocities due to the weakness of the WD kicks, such warmed FFPs can thus be associated with their former host stars for several Myr after formation. Therefore, WD formation kicks contribute a distinct, observationally identifiable FFP sub-population comprising a few percent of the Galaxy's FFPs, relevant for the design of future FFP surveys.
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Cosmology and Nongalactic Astrophysics

First Search for Kaluza-Klein Gravitons and Radion Using Planck Data

Alexander P. Cassem and Soubhik Kumar

Heavy moduli and Kaluza-Klein (KK) gravitons from extra dimensions may evade terrestrial probes but can be produced during inflation, generating primordial non-Gaussianity (NG) through unavoidable couplings to density perturbations. In a warped five-dimensional (5D) model, we compute the full radion- and KK-graviton-mediated bispectra and perform the first search for these signals using Planck 2018 temperature and polarization data. We find no significant evidence for NG, with the maximum significance being $1.8\sigma$ for $m_{\rm KK}\approx 1.6H$. We also identify a 5D setup which naturally generates NG with $f_{\rm NL}\sim 1-50$, within the reach of future surveys.
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Astrophysics of Galaxies

Investigating the star formation histories of galaxies from Cosmic Dawn to the Epoch of Reionization with the Santa Cruz SAM

L. Y. Aaron Yung, Rachel S. Somerville, Steven L. Finkelstein et al. (+1 more)

The James Webb Space Telescope (JWST) has opened a new window onto galaxy evolution in the very early Universe. In this work, we leverage halo merger trees extracted from the GUREFT dark-matter-only cosmological simulation suite together with the Santa Cruz semi-analytic model (SAM) for galaxy formation to investigate the predicted star formation histories (SFHs) of galaxies from cosmic dawn (z ~ 14) to the end of the Epoch of Reionization (EoR; z~6). While we find that on average, median SFHs of galaxies across all masses are uniformly and rapidly rising over time from 14 < z < 6 as expected, individual galaxy SFHs show a range of diverse SFHs, even for a fixed terminal mass or redshift, with bursts and mini-quenching episodes in agreement with SFHs inferred from observations. The median lookback time to form the youngest 50% (t_50) and 90% (t_90) of galaxies' stars decreases weakly with increasing stellar mass, and strongly with the redshift of observation. For galaxies at z>12, we find typical values of t_50 < 30 Myr and t_90 < 70 Myr, a factor of ~3 to 4 shorter than for comparable galaxies near the end of EoR (z ~ 6). The young-star dominated nature of stellar populations in ultra-high-z galaxies implies that careful modelling of young stellar populations is crucial for obtaining accurate synthetic photometry. In addition, our results have important implications for interpreting observational indicators of star formation histories and timescales.
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All authors L. Y. Aaron Yung, Rachel S. Somerville, Steven L. Finkelstein, Kartheik G. Iyer

High Energy Astrophysical Phenomena

High-Energy Neutrino Tomography of the Earth's Interior with IceCube

The IceCube Collaboration, R. Abbasi, M. Ackermann et al. (+417 more)

The Earth's interior reflects its geological evolution, from accretion to present-day dynamics. Its structure drives the geodynamo in the outer core, generating the magnetic field that shields the surface from charged cosmic radiation. The primary observables of the Earth's interior are its radial density distribution and derived quantities such as its mass and moment of inertia. These have traditionally been inferred from gravity and seismic wave propagation, which probe the macroscopic response of matter to gravitational and elastic forces. Here we instead constrain the Earth's density profile using high-energy neutrinos observed by the IceCube Neutrino Observatory at the South Pole. We analyze 10.7 years of predominantly muon-neutrino data spanning 500 GeV–100 TeV, including atmospheric neutrinos produced by cosmic-ray interactions in the Earth's atmosphere and the diffuse astrophysical neutrino flux. Neutrino attenuation depends on both the traversed column density and neutrino energy. By measuring the zenith- and energy-dependent flux suppression, we infer the Earth's radial density profile by fitting a concentric uniform-density shell model that incorporates neutrino fluxes, interaction cross sections, detector response, and glacial-ice systematic uncertainties. From the resulting density posteriors, we derive the Earth's mass and polar moment of inertia as measured by neutrinos. These are the most precise weak-interaction measurements of these quantities to date and are consistent with the Preliminary Reference Earth Model and independent gravitational determinations. Our results demonstrate that neutrinos provide a novel probe of planetary interiors via a distinct physical interaction, complementing gravity and seismology. With improved detectors and precision, neutrinos will further contribute to a multifaceted understanding of the Earth's structure.
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All authors The IceCube Collaboration, R. Abbasi, M. Ackermann, J. Adams, J. A. Aguilar, M. Ahlers, J.M. Alameddine, S. Ali, N. M. Amin, K. Andeen, C. Argüelles, S. Athanasiadou, S. N. Axani, R. Babu, X. Bai, A. Balagopal V., S. W. Barwick, V. Basu, R. Bay, J. J. Beatty, J. Becker Tjus, P. Behrens, J. Beise, C. Bellenghi, S. Benkel, S. BenZvi, D. Berley, E. Bernardini, D. Z. Besson, E. Blaufuss, L. Bloom, S. Blot, F. Bontempo, J. Y. Book Motzkin, C. Boscolo Meneguolo, S. Böser, O. Botner, J. Böttcher, J. Braun, B. Brinson, Z. Brisson-Tsavoussis, L. Brusa, R. T. Burley, D. Butterfield, K. Carloni, J. Carpio, N. Chau, Y. C. Chen, Z. Chen, D. Chirkin, S. Choi, A. Chubarov, B. A. Clark, G. H. Collin, D. A. Coloma Borja, A. Connolly, J. M. Conrad, D. F. Cowen, C. De Clercq, J. J. DeLaunay, D. Delgado, T. Delmeulle, S. Deng, P. Desiati, K. D. de Vries, G. de Wasseige, T. DeYoung, J. C. Díaz-Vélez, S. DiKerby, T. Ding, M. Dittmer, A. Domi, L. Draper, L. Dueser, D. Durnford, K. Dutta, M. A. DuVernois, T. Ehrhardt, L. Eidenschink, A. Eimer, C. Eldridge, P. Eller, E. Ellinger, D. Elsässer, R. Engel, H. Erpenbeck, W. Esmail, S. Eulig, J. Evans, P. A. Evenson, K. L. Fan, K. Fang, K. Farrag, A. Fattorini, A. R. Fazely, A. Fedynitch, N. Feigl, C. Finley, D. Fox, A. Franckowiak, S. Fukami, P. Fürst, J. Gallagher, E. Ganster, A. Garcia, M. Garcia, E. Genton, L. Gerhardt, A. Ghadimi, C. Glaser, T. Glüsenkamp, J. G. Gonzalez, S. Goswami, A. Granados, D. Grant, S. J. Gray, S. Griffin, S. Griswold, K. M. Groth, D. Guevel, C. Günther, P. Gutjahr, C. Ha, A. Hallgren, L. Halve, F. Halzen, L. Hamacher, M. Handt, K. Hanson, J. Hardin, A. A. Harnisch, P. Hatch, A. Haungs, J. Häußler, K. Helbing, J. Hellrung, B. Henke, L. Hennig, F. Henningsen, L. Heuermann, R. Hewett, N. Heyer, S. Hickford, A. Hidvegi, C. Hill, G. C. Hill, R. Hmaid, K. D. Hoffman, A. Hollnagel, D. Hooper, S. Hori, K. Hoshina, M. Hostert, W. Hou, M. Hrywniak, T. Huber, K. Hultqvist, K. Hymon, A. Ishihara, W. Iwakiri, M. Jacquart, S. Jain, O. Janik, M. Jansson, M. Jin, N. Kamp, D. Kang, W. Kang, A. Kappes, L. Kardum, T. Karg, A. Karle, A. Katil, M. Kauer, J. L. Kelley, M. Khanal, A. Khatee Zathul, A. Kheirandish, T. Kim, H. Kimku, F. Kirchner, J. Kiryluk, C. Klein, S. R. Klein, Y. Kobayashi, S. Koch, A. Kochocki, R. Koirala, H. Kolanoski, T. Kontrimas, L. Köpke, C. Kopper, D. J. Koskinen, P. Koundal, M. Kowalski, T. Kozynets, A. Kravka, N. Krieger, T. Krishnan, K. Kruiswijk, E. Krupczak, E. Kun, N. Kurahashi, C. Lagunas Gualda, L. Lallement Arnaud, M. J. Larson, F. Lauber, J. P. Lazar, K. Leonard DeHolton, A. Leszczyńska, C. Li, J. Liao, C. Lin, Q. R. Liu, Y. T. Liu, M. Liubarska, C. Love, L. Lu, F. Lucarelli, W. Luszczak, Y. Lyu, M. Macdonald, E. Magnus, Y. Makino, E. Manao, S. Mancina, A. Mand, I. C. Mariş, S. Marka, Z. Marka, L. Marten, I. Martinez-Soler, R. Maruyama, J. Mauro, F. Mayhew, F. McNally, K. Meagher, A. Medina, M. Meier, Y. Merckx, L. Merten, S. Minji, J. Mitchell, L. Molchany, S. Mondal, T. Montaruli, R. W. Moore, Y. Morii, A. Mosbrugger, D. Mousadi, E. Moyaux, T. Mukherjee, M. Nakos, U. Naumann, R. Neshat, L. Neste, M. Neumann, H. Niederhausen, M. U. Nisa, K. Noda, A. Noell, A. Novikov, A. Obertacke, V. O'Dell, A. Olivas, R. Orsoe, J. Osborn, E. O'Sullivan, B. Owens, V. Palusova, H. Pandya, A. Parenti, C. Parisel, N. Park, V. Parrish, E. N. Paudel, L. Paul, C. Pérez de los Heros, T. Pernice, T. C. Petersen, J. Peterson, S. Pick, M. Plum, A. Pontén, V. Poojyam, B. Pries, R. Procter-Murphy, G. T. Przybylski, L. Pyras, C. Raab, J. Rack-Helleis, N. Rad, M. Ravn, K. Rawlins, Z. Rechav, A. Rehman, I. Reistroffer, E. Resconi, C. D. Rho, W. Rhode, L. Ricca, B. Riedel, A. Rifaie, E. J. Roberts, S. Rodan, M. Rongen, A. Rosted, C. Rott, T. Ruhe, L. Ruohan, D. Ryckbosch, J. Saffer, D. Salazar-Gallegos, P. Sampathkumar, A. Sandrock, G. Sanger-Johnson, M. Santander, S. Sarkar, M. Scarnera, M. Schaufel, H. Schieler, S. Schindler, L. Schlickmann, B. Schlüter, F. Schlüter, N. Schmeisser, T. Schmidt, A. Scholz, F. G. Schröder, S. Schwirn, S. Sclafani, D. Seckel, L. Seen, M. Seikh, S. Seunarine, P. A. Sevle Myhr, R. Shah, S. Shah, S. Shefali, N. Shimizu, B. Skrzypek, R. Snihur, J. Soedingrekso, D. Soldin, P. Soldin, G. Sommani, D. Song, C. Spannfellner, G. M. Spiczak, C. Spiering, J. Stachurska, M. Stamatikos, T. Stanev, T. Stezelberger, T. Stürwald, T. Stuttard, G. W. Sullivan, I. Taboada, S. Ter-Antonyan, A. Terliuk, A. Thakuri, M. Thiesmeyer, W. G. Thompson, J. Thwaites, S. Tilav, K. Tollefson, J. A. Torres, S. Toscano, D. Tosi, K. Upshaw, A. Vaidyanathan, N. Valtonen-Mattila, J. Valverde, J. Vandenbroucke, T. Van Eeden, N. van Eijndhoven, L. Van Rootselaar, J. van Santen, J. Vara, F. Varsi, M. Velazquez, M. Venugopal, M. Vereecken, S. Vergara Carrasco, S. Verpoest, D. Veske, A. Vijai, J. Villarreal, C. Walck, A. Wang, E. H. S. Warrick, C. Weaver, P. Weigel, A. Weindl, J. Weldert, A. Y. Wen, C. Wendt, J. Werthebach, M. Weyrauch, N. Whitehorn, C. H. Wiebusch, D. R. Williams, L. Witthaus, G. Wrede, X. W. Xu, J. P. Yanez, Y. Yao, E. Yildizci, S. Yoshida, F. Yu, S. Yu, T. Yuan, S. Yun-Cárcamo, A. Zander Jurowitzki, A. Zegarelli, S. Zhang, Z. Zhang, P. Zhelnin, P. Zilberman, C. Zilleruelo Cañas

High Energy Astrophysical Phenomena

A Shock-based Interpretation of Radio and X-ray Emission in Active Galactic Nuclei

Fan Wu and Benzhong Dai

We propose a shock-based framework to interpret the radio and X-ray emission in active galactic nuclei (AGNs), whose origin remains an open problem. In this framework, the radio emission is produced by synchrotron radiation in the accretion flow or a jet/weak outflow, while the dominant X-ray component depends on the accretion state, the location of the non-thermal emission region, and the available seed photon field. The model provides a self-consistent interpretation of radio and X-ray emission in typical non-jetted AGNs, including low-luminosity AGNs, Seyfert galaxies, and radio-quiet quasars. In jetted AGNs, our results disfavor scenarios in which the non-thermal electrons responsible for X-ray emission are accelerated in the disk or the corona. We use two widely discussed empirical diagnostics, radio loudness and the fundamental plane (FP) of black hole (BH) activity, to assess the applicability and limitations of the model. It can naturally explain the observed trends that the radio loudness increases with BH mass and decreases with the Eddington ratio. The observed slope of the FP depends on how the key physical quantities scale with the accretion rate. As the accretion rate increases, the advection-dominated accretion flow region contracts while the thin disk region expands, reflecting a transition toward a more radiatively efficient accretion structure. The Eddington ratio therefore influences the accretion structure, and may in turn shape the observed AGN classes.
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Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph

A critical look at low-scale cosmological phase transitions in the PTA era

Simone Biondini and Philipp Schicho

Motivated by the recent evidence for a stochastic gravitational-wave (GW) background reported by pulsar timing array (PTA) collaborations, we perform a precision study of low-scale phase transitions in a dark Abelian Higgs sector, a minimal gauge theory of spontaneous symmetry breaking relevant for cosmological phase transitions. Using dimensionally reduced high-temperature effective field theory, we quantify the impact of thermal resummation, higher-order matching corrections, and higher-dimensional operators on the phase-transition thermodynamics and the resulting GW signal. We find that the parameter region favored by current PTA observations lies close to the boundary of validity of the effective field theory, where higher-dimensional operators become increasingly important. Even within this controlled region, the predicted signal remains disfavored by the PTA data, despite the substantial shifts induced by higher-order thermal corrections. We further delineate parameter regions where the dark and visible sectors are thermally and hydrodynamically coupled or decoupled, and revisit the dark matter phenomenology, identifying asymmetric freeze-out as naturally compatible with both the observed relic abundance and the gauge couplings favored by strong phase transitions. Our results underscore the importance of systematically controlled finite-temperature calculations for reliable GW predictions from low-scale cosmological phase transitions.
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Cosmology and Nongalactic Astrophysics

Alleviating prior dependencies for DESI DR1 clustering fits through reparameterization

Marco Bonici, Simone Paradiso, Glenn McGee et al. (+48 more)

Bayesian analyses of the full-shape clustering of Dark Energy Spectroscopic Instrument (DESI) Data Release 1 (DR1) exhibit prior-volume projection effects, whereby weakly constrained nuisance parameters of the Effective Field Theory of Large Scale Structure (EFTofLSS) shift marginalized cosmological posteriors away from the posterior maximum. We reanalyze DESI DR1 power spectrum multipoles using two complementary mitigation strategies: (i) nonlinear orthogonalization to decorrelate nuisance and cosmological parameter priors, and (ii) a fully reparameterization-invariant Jeffreys prior over all EFTofLSS coefficients, evaluated on-the-fly via closed-form Jacobians. Including data from DESI, Big-Bang Nuclesynthesis and a constraint on $n_{\mathrm{s}}$, baseline priors lead to multi-$\sigma$ projection in the Hubble parameter $H_{0}$ and dark energy equation of state parameters $w_{0}$ and $w_{a}$; the Jeffreys prior successfully recenters these posteriors to enclose the maximum a posteriori estimate within the 68% credible regions, demonstrating clear mitigation of projection effects for these late-time expansion parameters. A hybrid Jeffreys+baseline-Gaussian configuration controls residual over-broad tails in the physical cold dark matter density $\omega_{\mathrm{c}}$ while preserving the volume correction, and is our favoured approach. We compare the credible intervals derived using our methodology to those obtained using Halo Occupation Distribution (HOD)-informed priors and to confidence intervals derived using frequentist profile likelihood analyses, finding agreement in both central values and degeneracy directions in the $w_{0}$–$w_{a}$ plane. This demonstrates that, once projection effects are properly controlled, we can make robust inferences about the late-time cosmological expansion independent of the statistical framework adopted.
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All authors Marco Bonici, Simone Paradiso, Glenn McGee, Guido D'Amico, Minas Karamanis, Hanyu Zhang, Will Percival, Jessica Nicole Aguilar, Steven Ahlen, Davide Bianchi, David Brooks, Francisco Javier Castander, Todd Claybaugh, Axel de la Macorra, Biprateep Dey, Peter Doel, Simone Ferraro, Andreu Font-Ribera, Jaime E. Forero-Romero, Enrique Gaztañaga, Satya Gontcho A Gontcho, Gaston Gutierrez, ChangHoon Hahn, Klaus Honscheid, Mustapha Ishak, Dick Joyce, Robert Kehoe, Theodore Kisner, Anthony Kremin, Ofer Lahav, Claire Lamman, Martin Landriau, Laurent Le Guillou, Marc Manera, Aaron Meisner, Ramon Miquél, Gustavo Niz, Francisco Prada, Ignasi Pérez-Ràfols, Graziano Rossi, Lado Samushia, Eusebio Sanchez, Edward Schlafly, David Schlegel, Joseph Harry Silber, David Sprayberry, Gregory Tarlé, Mariana Vargas Magana, Benjamin Alan Weaver, Pauline Zarrouk, Hu Zou