Cosmology and Nongalactic Astrophysics
Effective Field Theory for a Baryon-Correlated Dark Matter Profile
Kento Kamada
While the standard $\Lambda$CDM model succeeds on large cosmological scales, it faces persistent small-scale challenges, including the core-cusp problem, the diversity of
galaxy rotation curves, and the tight correlation between dark matter and
baryons observed in the Tully-Fisher relation. To address these issues, we recently proposed an empirical law where the effective dark matter energy density is directly correlated with the baryonic gravitational potential, $\rho_{\rm DM} \propto \Phi_b^2$, which reproduces observed rotation curves and resolves the core-cusp and diversity problems. To provide a theoretical foundation for this empirical law, we construct an effective field theory (EFT) introducing massive scalar, vector, and tensor mediators between
baryons and a dark sector field $\chi$. We demonstrate that aligning the mediator couplings to a specific ratio (4:6:3) with degenerate masses cancels the additional fifth forces acting on
baryons up to $\mathcal{O}(v^2)$. We then show that this theoretical framework originates from a 5-dimensional (5D) spacetime. Treating the baryonic source as a 5D null fluid reveals that the three mediators emerge from a single 5D symmetric tensor field. By confining the field $\chi$ to a 4D brane, we show that its interaction with these mediators generates a pressureless energy density ($\rho_{\rm int} \propto \Phi_b^2$) that yields the empirically required
baryon-correlated profile. Consequently, the field $\chi$ exhibits a scale-dependent transition: on cosmological scales, its mass energy acts as standard Cold Dark Matter (CDM), whereas on
galactic scales, its interaction energy governs local dynamics. Finally, by evaluating the dynamical boundary of this localized interaction region, we provide a physical interpretation that yields the relation $\mu = K M_b^{-3/2}$, offering a theoretical basis for the Tully-Fisher relation.
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Solar and Stellar Astrophysics
Continuous mass ablation of planets engulfed in stellar envelopes
Mike Y. M. Lau, Robert Andrassy, Giovanni Leidi et al. (+4 more)
Most
stars host short-period
planets that are expected to be engulfed during post-main-sequence expansion. The dissolution of engulfed
planets has been proposed as a possible mechanism for producing
stars enriched in lithium and refractory elements. We perform three-dimensional hydrodynamical simulations of a Jupiter-like
planet engulfed within a
stellar envelope using the Seven-League Hydro code. Unlike previous studies that represent the
planet as a point mass or rigid sphere, we adopt a wind-tunnel setup that resolves the
planet's gaseous structure. We find that a continuous mass-ablation process operates during planetary engulfment, contrary to the common assumption that destruction occurs at a specific depth due to ram pressure,
tidal forces, or thermal evaporation. The ablation rate scales nearly linearly with the wind momentum flux and is largely insensitive to the Mach number, consistent with an analytical model based on Kelvin-Helmholtz instability developing at the planetary surface. We define efficiency coefficients for drag and ablation, finding pressure-drag coefficients of 0.44-0.56 and smaller ablation efficiencies of 0.054-0.11. Applying these coefficients to a numerically integrated inspiral through a
stellar profile, we find that continuous ablation could lead to complete dissolution of the
planet within the convective envelope, producing observable lithium enrichment at the
stellar surface. Our results provide prescriptions for drag and mass loss that enable large parameter-space studies of planetary engulfment and suggest that chemical enrichment may occur over a broader range of
stellar parameters than previously thought.
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All authors Mike Y. M. Lau, Robert Andrassy, Giovanni Leidi, Damien Gagnier, Javier Morán-Fraile, Friedrich K. Röpke, Ilya Mandel
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Reviving primordial black hole formation in slow first-order phase transitions
Wen-Yuan Ai and Ke-Pan Xie
Large
curvature perturbations generated during slow first-order phase transitions are a promising source of
primordial black holes. However, recent analyses suggested that the mechanism is ruled out once the density contrast and the formation threshold are evaluated in the same gauge. In this work, we show that this mechanism remains viable: after a supercooled transition, reheating can be sufficiently slow that the Universe enters an early matter-dominated era, during which even small overdensities grow and collapse into
primordial black holes.
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Instrumentation and Methods for Astrophysics
Optical Design of OPTICAM-ARG: A Three-Channel High-Time-Resolution Camera for the Jorge Sahade Telescope
M. R. Najera, J. Herrera Vazquez, E. Luna et al. (+5 more)
We present the optical design of OPTICAM-ARG, a multi-channel instrument for the simultaneous acquisition of images in three spectral bands at the Cassegrain focus of an f/8.5
telescope, covering the 0.35 to 1.00 um wavelength range. The converging beam delivered by the
telescope is spectrally separated by two dichroics into three channels, blue, green, and red, each incorporating a dedicated three-lens focal reducer, an interchangeable SDSS filter stage, and an sCMOS detector. The focal reducers establish an effective focal length of approximately 9.1 m, a uniform plate scale of 22.6 arcsec/mm, and a field of view of 8.4 arcmin x 8.4 arcmin per channel, consistent with the typical seeing conditions at the site. Operation of the dichroics in a converging beam introduces off-axis aberrations, which are mitigated through wedge angles applied to their second surface and optimized as part of the global design. Optical performance is assessed through exact ray tracing using RMS spot radii and encircled energy metrics, with EE50 values further expressed in terms of an equivalent FWHM to enable direct comparison with atmospheric seeing and to evaluate sensitivity to manufacturing tolerances.
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All authors M. R. Najera, J. Herrera Vazquez, E. Luna, A. Castro, D. Altamirano, R. Michel, S. A. Cellone, E. Sohn
Solar and Stellar Astrophysics · Cross-listed from physics.plasm-ph
Amir Jafari
Dynamic
alignment in MHD
turbulence is commonly interpreted as a tendency of Elsässer increments to align toward smaller inertial-range scales. This interpretation is based on the amplitude-weighted diagnostic \(\langle A_r\sin\theta_r\rangle/\langle A_r\rangle\), where \(A_r\) is the product of the two increment amplitudes and \(\theta_r\) is the unweighted folded angle. We show that a decrease of the weighted angle toward smaller scales does not require dynamical
alignment but can arise from a retention effect in measurements. At fixed scale, larger amplitudes correlate with smaller angles, making the weighted angle smaller than the unweighted angle without implying that the angular population evolves toward
alignment with scale. The same covariance-driven reweighting structure underlies the Price equation in evolutionary biology. Applied here in scale space, it separates angular
evolution from redistribution of amplitude weight: a lower measured weighted angle at smaller scales can reflect reweighting even when the unweighted angle remains nearly scale independent. In physical time, the picture predicts that, after matching initial amplitudes, high-amplitude large-angle fluctuations lose a larger amplitude fraction over finite lags than high-amplitude small-angle fluctuations, favoring intense small-angle events in weighted statistics. This retention picture allows perpendicular rms Elsässer increments to scale as \(\ell_\perp^{1/4}\), corresponding to an effective \(k_\perp^{-3/2}\) spectrum, without requiring dynamic
alignment of typical fluctuations. We test these results using the Johns Hopkins
Turbulence Database and NASA Wind measurements. Mean logarithmic increment amplitudes give steeper typical-amplitude slopes than rms-amplitude fits in both
datasets, showing stronger sensitivity of second-order statistics to intermittent intense events.
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Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc
Closing the Cosmographic Hierarchy: Dynamical Attractors from Inflation to Reheating
Seturumane Tema, S. Shajidul Haque, Saurya Das et al. (+1 more)
We develop a potential-independent cosmographic framework, in which cosmographic parameters are promoted to dynamical variables within a closed autonomous system. Although the cosmographic hierarchy is formally infinite, we achieve closure by mapping potential slow-roll parameters onto the kinematic phase space within General Relativity with a minimally coupled scalar field. Within this framework, we perform a stability analysis and show that inflationary (quasi-de Sitter) solutions arise as natural attractors, while stiff-fluid configurations act as repellers without invoking the slow-roll approximation. To describe the transition to standard Big Bang
evolution, we extend the system to include a radiation component and a phenomenological decay term. This leads to a generalized, potential-independent description of reheating characterized by an effective equation of state $w_{\rm eff}$. We demonstrate that the radiation-dominated phase is the late-time attractor of the extended system. These results provide a unified kinematical description of the expansion history from inflation through reheating, bridging cosmography and scalar field dynamics.
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All authors Seturumane Tema, S. Shajidul Haque, Saurya Das, Peter Dunsby
High Energy Astrophysical Phenomena
Black Hole Binary Detection Landscape for the Laser Interferometer Lunar Antenna (LILA): Signal-to-Noise Calculations & Science Cases
Tintin Nguyen, Anjali Yelikar, Ryan Nowicki et al. (+2 more)
The
Laser Interferometer Lunar
Antenna (LILA) is a proposed gravitational-wave project aiming to take full advantage of the Moon's environment to access the deci-Hz band and detect intermediate-mass black hole (IMBH) binaries of mass $\sim 10^2-10^6 \, M_{\odot}$ (arXiv:2508.11631). With an observational period of 4 years, LILA can extend its IMBH detection horizon to the very early Universe, directly probing the first population of massive black holes ($z \sim 20-30$). LILA could also detect intermediate-mass-ratio inspiral systems with a total mass of $\sim 10^4 - 10^6 \, M_{\odot}$ and a mass ratio of $\sim 10^{-4} - 10^{-2}$. LILA can discover IMBH binaries months to years before merger with measurable eccentricity residuals retained from their formation, providing crucial early warning for multi-messenger and multi-band follow-up. The high SNR ($\gtrsim 100$) events detectable with LILA would enable strong-field tests of
gravity. With these capabilities, LILA will provide important insights into the formation and
evolution of massive black holes, as well as the astrophysical environments and evolutionary pathways of black hole binaries. LILA will also complement current LIGO/Virgo/KAGRA detections of pair-instability mass gap events, hierarchical merger candidates, and light IMBH mergers, while expanding the upper envelope of discovered black holes with
stellar origin to masses of $\gtrsim 250 \, M_{\odot}$.
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All authors Tintin Nguyen, Anjali Yelikar, Ryan Nowicki, Karan Jani, Angelo Ricarte
High Energy Astrophysical Phenomena · Cross-listed from gr-qc
Discovery of Interpretable Surrogates via Agentic AI: Application to Gravitational Waves
Tousif Islam, Digvijay Wadekar, Tejaswi Venumadhav et al. (+4 more)
Fast surrogate models for expensive simulations are now essential across the sciences, yet they typically operate as black boxes. We present GWAgent, a large
language model (LLM)-based workflow that constructs interpretable analytic surrogates directly from simulation data. Surrogate modeling is well suited to agentic workflows because candidate models can be quantitatively validated against ground-truth simulations at each iteration. As a demonstration, we build a surrogate for gravitational waveforms from eccentric binary black hole mergers. We show that providing the
agent with a physics-informed domain ansatz substantially improves output model accuracy. The resulting analytic surrogate attains a median Advanced LIGO mismatch of $6.9\times10^{-4}$ together with an $\sim 8.4\times$ speedup in waveform evaluation, surpassing both symbolic regression and conventional machine learning baselines. Beyond producing an accurate model, the workflow identifies compact physical structure from the learned representation. As an astrophysical application, we use GWAgent to analyze the eccentricity of GW200129 and infer $e_{20\mathrm{Hz}}=0.099^{+0.063}_{-0.044}$. These results show that validation-constrained agentic workflows can produce accurate, fast, and interpretable surrogates for scientific simulations and inference.
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All authors Tousif Islam, Digvijay Wadekar, Tejaswi Venumadhav, Matias Zaldarriaga, Ajit Kumar Mehta, Javier Roulet, Barak Zackay
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Absorption of Gravitons and Photon Luminosities of Interstellar/Intergalactic Hydrogen Atoms
George Savvidy and Pavlos Savvidis
We compute the emission and absorption rates of gravitons by hydrogen atoms. The absorption rate of gravitons is proportional to the number of hydrogen atoms and to the graviton luminosity. The number of hydrogen atoms in interstellar/intergalactic media can be large while the graviton luminosity of Sun, or a typical
star, is in the eV to keV range that well overlaps with the resonance frequencies of the hydrogen atoms. Currently, the observational knowledge of the graviton luminosity in different regions of the Universe is limited, and here we will consider its value as unknown quantity that should be determined by independent astrophysical observations. We suggest measuring the ratio of the
photon luminosities from interstellar/intergalactic hydrogen atoms that can provide information concerning the luminosity of gravitons in different regions of space. This ratio maximally exposes the fundamental physical nature of
photons and gravitons - their helicity, which is one for the
photons and two for the gravitons. The ratio is sensitive to any sources of gravitational radiation and provide a possible method for measuring their radiation intensities.
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Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc
End-to-End Population Inference from Gravitational-Wave Strain using Transformers
Konstantin Leyde, Stephen R. Green, Maximilian Dax et al. (+3 more)
The population of compact binaries encodes information about their astrophysical origins and the expansion of the universe. Hierarchical
Bayesian methods infer these properties by combining single-event posteriors. As catalogs grow, however, this approach becomes computationally expensive and is subject to increasing Monte Carlo uncertainty. We introduce Dingo-Pop, a simulation-based framework that infers population posteriors directly from gravitational-wave strain data. The data for each event are embedded into low-dimensional
tokens and combined using a
transformer trained on simulated catalogs subject to selection effects. This enables (i) population inference without per-event Monte Carlo sampling noise, (ii) amortization across variable catalog sizes using a single network, and (iii) end-to-end inference in about one second. We train a network for catalog sizes of 25 to 1000 events, and obtain well-calibrated posteriors consistent with traditional methods. By avoiding per-event analyses that can take hours to days, Dingo-Pop enables new classes of large-scale injection studies; as an application, we examine how spectral-siren Hubble constant uncertainties change with catalog size.
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All authors Konstantin Leyde, Stephen R. Green, Maximilian Dax, Matthew Mould, Cecilia Maria Fabbri, Jonathan Gair
High Energy Astrophysical Phenomena · Cross-listed from gr-qc
gwBenchmarks: Stress-Testing LLM Agents on High-Precision Gravitational Wave Astronomy
Tousif Islam, Digvijay Wadekar and Zihan Zhou
Modern gravitational wave astronomy relies on modeling tasks that often require months of graduate-level effort, including building fast waveform surrogates from expensive numerical relativity simulations, modeling orbital dynamics of black holes, fitting merger remnant properties and constructing template banks. These problems demand extreme precision to support detection and parameter inference, with state-of-the-art models achieving $\lesssim 10^{-4}$ relative error. We study whether state-of-the-art LLM coding
agents can perform such end-to-end scientific modeling, where success requires constructing models with stringent accuracy criteria and
reasoning about physical systems. We introduce gwBenchmarks, a suite of eight tasks grounded in gravitational wave analytic calculations and numerical simulations collectively representing over $10^8$ core-hours of compute. The tasks span interpolation, regression, and high-dimensional time-series modeling, requiring a combination of numerical methods, machine learning, and physics-informed approaches. In preliminary experiments,
agents frequently relied on proxy metrics, partial evaluation, or fabricated results to spuriously complete tasks. We therefore implement an external pre-defined framework to gauge
agent progress. Evaluating twelve coding
agents, we find no consistent winner. On the easiest task, multiple
agents converge to the same cubic spline solution, with one rediscovering a coordinate transformation widely used in the literature. On harder tasks like analytic waveform modeling, all
agents fall 1-2 orders of magnitude short of domain requirements and exhibit systematic failures, including metric misuse, constraint violations, and result fabrication. Our code, data, and website are publicly available.
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Astrophysics of Galaxies
Variable stars in the field of the Galactic globular cluster M71
C. C. Cortés, D. Deras, A. Arellano Ferro et al. (+2 more)
M71 is a nearby, metal-rich globular cluster at low
Galactic latitude, where field contamination and spatially variable extinction complicate colour-magnitude diagrams (CMDs) and the identification of cluster member variable
stars. Our aims are (i) to construct a homogeneous census of variable
stars in M71 by refining their periods and classifications and identifying new candidates, and (ii) to derive a decontaminated, differentially dereddened CMD to constrain its physical properties. We obtained Johnson-Kron-Cousins $VI$ time-series CCD photometry and reduced it using difference image analysis. Cluster membership was established from
Gaia~DR3 proper motions, and a differential-reddening correction was applied across the field of view. The resulting CMD, cleaned of field
stars, was compared with tailored isochrones to estimate age ($12.9^{+0.9}_{-0.8}$ Gyr),
metallicity ([Fe/H] =$-0.88^{+0.13}_{-0.15}$), mean reddening ($E(B-V)$ = $0.21 \pm 0.02$), and distance modulus ($(m-M)_{0}$ = $13.01 \pm 0.06$). Variable
stars were identified using two complementary approaches: a periodogram-free string-length scan refined with phase dispersion minimisation, and a robust inter-site screening based on median statistics combined with a generalised Lomb-Scargle significance criterion. We identified 21 variable
stars not previously reported in the Catalog of Variable
Stars in Globular Clusters and provided their periods, amplitudes, classifications, membership status, and light curves. This combined strategy yields a consistent picture of M71, expanding its known variable-
star population and confirming parameters typical of metal-rich
Galactic disk globular clusters.
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All authors C. C. Cortés, D. Deras, A. Arellano Ferro, S. Muneer, I. H. Bustos Fierro
Solar and Stellar Astrophysics · Cross-listed from nucl-th
The mean-field theory of superfluid-superconducting vortex states in the outer core of neutron stars
Dmitry Kobyakov
Purpose: Characterize superfluid-superconducting
vortex states at arbitrary pressures with $T_{cp}\neq T_{cn}$, assuming both
proton and
neutron mean-fields are formed by
spin-0 Cooper pairs. Method: The existing mean-field theory is extended to account for $T_{cp}\neq T_{cn}$. The pressure dependence of the pairing gap energy $\Delta_{\alpha0}$ is quantitatively established on the basis of the effective
chiral field theory. To link $T_{c\alpha}$ with $\Delta_{\alpha0}$, I use the weak-coupling result $T_{c\alpha}\approx0.57\Delta_{\alpha0}$. A quadratic scaled-temperature ($T/T_{cp}$) dependence of the thermodynamic
magnetic field is postulated in analogy with pure
superconductors. The $T/T_{c\alpha}$-dependence of the gap $\Delta_{\alpha T}$ is inferred from the many-body approximations for the pure
neutron matter. Results: An empirical $T/T_{c\alpha}$-dependence for the mean-field is constructed to account for the interplay between the condensation and the
magnetic energies. The superfluid entrainment is found to increase the size of the
vortex core and to decrease the effective
magnetic penetration depth. The size of the
neutron vortex core is found to be larger than the
magnetic penetration depth in the outer core. Conclusions: The usual approximation of infinitely thin
vortex line (the London's approximation) for the
neutron vortex is found to be irrelevant in the entire outer core and for the
proton vortex is found to be limited to vicinity of the crust-core transition. The developed mean-field theory paves the way to study the
vortex microscopic structure, the angular momentum, the magnetization and the
vortex-fluxtube interaction energy.
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Astrophysics of Galaxies
The applicability of the JAGB method for measuring the distance of galaxies subject to different metal enrichment rates
Claudio Gavetti, Paolo Ventura, Flavia Dell'Agli et al. (+4 more)
The JAGB method has been proposed in recent years as a possible distance indicator for
galaxies in the Local Group and beyond. However, the nature of the
stars populating the J region, and the conditions required for the direct application of this method, still need to be clarified. We investigate the robustness of the JAGB method through a detailed theoretical analysis of the
stars populating the J region of the (J-Ks, J) diagram. The main goal is to identify the properties of the corresponding J luminosity function (JLF) that are minimally affected by the previous evolutionary history of the host
galaxy, particularly its metal enrichment history. We use a population synthesis approach based on AGB
stellar evolution models coupled consistently with
dust formation in the
stellar wind. Synthetic
stellar distributions in the (J-Ks, J) diagram and the related JLFs are calculated for different assumptions on the
metallicity evolution of the interstellar medium, in order to study how the JLF depends on the efficiency of metal enrichment. We find that the JAGB population is dominated by
stars formed between about 1 and 6 Gyr ago, while
stars formed outside this interval contribute only marginally to the JAGB region. The shape of the JLF strongly depends on the metal enrichment history, and the position of the J-band peak varies by more than 0.3 mag among the different cases explored. Conversely, the mean J-band magnitude, MavJ, is much less sensitive to the previous history of the
galaxy and therefore represents a more reliable distance indicator. For all the cases investigated we find MavJ = -6.2 +/- 0.05 mag. We also discuss the uncertainties related to the still poorly constrained mass-loss process experienced by low-mass
stars during the red
giant branch phase.
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All authors Claudio Gavetti, Paolo Ventura, Flavia Dell'Agli, Luca Graziani, Matteo Correnti, Chiara Ventura, Fabio La Franca
Cosmology and Nongalactic Astrophysics
Prospects for multi-messenger discovery of the gravitational-wave background anisotropies via cross-correlation with galaxies
Raphael Bertrand-Delgado, Felipe Andrade-Oliveira, Michael Ebersold et al. (+1 more)
We present new empirically grounded forecasts for the detectability of the
stochastic gravitational-wave background anisotropies assuming a population of
stellar-mass compact binary coalescences as its source. We quantified the discovery potential using simulations based on the Euclid Flagship
Galaxy Catalogue and LIGO-Virgo-KAGRA observational constraints in combination with detailed theoretical modelling. We considered the multi-messenger cross-correlation with
galaxies as well as the gravitational wave-only cross-correlation across observation-time bins. For compact binaries up to
redshift $z<3$, we found that an angular resolution of $\theta = 4.1$ deg ($\ell \geq 44$) is required for discovery within five years of observation via cross-correlation with a
galaxy catalogue that is complete up to limiting magnitude $i < 24.7$ and has
redshift uncertainties $\sigma_z = 0.003 (1+z)$. Extending the time range to ten years alleviates that requirement to $\theta = 6.5$ deg ($\ell \geq 28$). We also showed that binning the
galaxies in
redshift allows us to reconstruct the
evolution of the kernel, which can be used to further constrain compact binary population models. Discovery without a multi-messenger tracer has proven significantly more challenging, requiring exclusion of the loudest events, $\theta = 1.8$ deg ($\ell \geq 95$), and a favourable coalescence rate. In light of the plans being carried out in the community for ongoing and upcoming
galaxy surveys, this work bodes well for the multi-messenger discovery and exploration of the
stochastic gravitational-wave background in the era of next-generation observatories such as the Einstein
Telescope and
Cosmic Explorer.
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All authors Raphael Bertrand-Delgado, Felipe Andrade-Oliveira, Michael Ebersold, Marcelle Soares-Santos
Astrophysics of Galaxies
The Extended Plane of the Local Supercluster
P. J. E. Peebles
An update of the evidence that
radio galaxies and clusters of
galaxies are more common than average near the plane of the de Vaucouleurs Local Supercluster shows that in the distance range 100 to 200Mpc objects whose positions are correlated with the plane of the Local Supercluster include
galaxies that are exceptionally luminous at two microns,
radio galaxies, and clusters of
galaxies. There can be little doubt about this property of
cosmic structure. I also argue for detection of this correlation for the
galaxies at 400Mpc distance that are exceptionally luminous at two microns. It will be interesting to learn whether these results are expected in the standard cosmology.
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Instrumentation and Methods for Astrophysics
From raw data to neutrino candidates: a neural-network pipeline for Baikal-GVD
A. Matseiko, G. Plotnikov and I. Kharuk
We present a neural-network-based data processing pipeline for Baikal-GVD, designed to improve event reconstruction quality and accelerate
neutrino candidates selection. The pipeline comprises three stages: fast suppression of extensive air shower events, suppression of noise optical modules activations, and extraction of high confidence
neutrino candidates. All three networks employ a
transformer architecture that exploits inter-hit correlations through the
attention mechanism. Applied sequentially, the pipeline achieves orders-of-magnitude speedup over the standard reconstruction chain. Moreover, noise suppression neural network surpasses the accuracy of algorithmic noise suppression
algorithms and provides estimate for time residuals of the signal hits, which is crucial for identification of track-like hits. We address the domain shift between Monte Carlo simulations and experimental data by incorporating a domain adaptation technique, demonstrating improved agreement between the two domains. The resulting framework enables near-real-time event classification, with direct applications to multi-messenger alert systems and diffuse
neutrino flux measurements.
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Instrumentation and Methods for Astrophysics
Quantifying the Reconstructability of Astrophysical Methods with Large Language Models and Information Theory: A Case Study in Spectral Reconstruction
Hsing Wen Lin and Zong-Fu Sie
Modern astrophysical studies rely heavily on complex data analysis pipelines; however, published descriptions often lack the detail required for computational reproducibility. In this work, we present an information-theoretic framework to quantify how effectively a method can be reconstructed from its written description. By treating algorithmic reconstruction as a probability distribution generated by Large
Language Models (LLMs), we utilize Shannon
entropy and Jensen-Shannon divergence to measure how strongly text constrains the hypothesis space of valid implementations. We demonstrate this approach through a case study of Trans-Neptunian Object (TNO) spectral reconstruction from sparse photometry. By prompting frontier LLMs with varying levels of manuscript text (Title, Abstract, and Methods), we find that while increasing text successfully clarifies the overall algorithmic structure, it fails to eliminate variance at the implementation level. This persistent variance establishes an "
entropy floor," demonstrating that multiple divergent implementations remain consistent with explicit instructions. To evaluate practical reproducibility, we convert these reconstructed
algorithms into executable pipelines. Our results reveal that, while LLMs easily recover core functional methodologies, they systematically fail to infer the tacit expert knowledge required for strict scientific calibration. This pilot study demonstrates that LLMs can be repurposed as a zero-shot diagnostic tool to audit methodological transparency, helping authors identify missing structural constraints and preserve scientific integrity in an era of automated research.
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Earth and Planetary Astrophysics
An Outer Giant Planet or Brown Dwarf in the 51 Pegasi System?
Marvin Morgan, Brendan P. Bowler, Kyle Franson et al. (+15 more)
51 Pegasi harbors the first confirmed extrasolar
planet orbiting a Sun-like
star. Decades of continued radial velocity (RV) observations have since uncovered signatures of an additional distant companion in the system from a shallow radial acceleration. We present new constraints on the mass and separation of a potential outer companion based on a synthesis of RVs, absolute astrometry, and new high-contrast imaging. Our analysis combines 31 years of new and previously published RV measurements from the OHP/ELODIE, Lick/Hamilton, Keck/HIRES, and APF/Levy spectrographs; a $\sim$25-year baseline of absolute astrometry from Hipparcos and
Gaia; and deep imaging from Keck/NIRC2 and HST/WFPC2. We find evidence for
curvature in the RVs, which when combined with non-detections from imaging and astrometry point to a super-Jupiter at $\simeq$15–100 AU or brown
dwarf companion at $\approx$20–170 AU. However, the inferred radial acceleration of the host
star is driven primarily by the Lick/Hamilton
dataset and its slope is consistent with long-term instrument drift, calling into question the nature of the long-period signal. If an outer companion is present, it could explain the origin of the inner hot Jupiter if 51 Peg b arrived at its current location through high-eccentricity migration. On the other hand, if the signal is spurious, the exceptional baseline rules out Jovian
planets within $\sim$10 AU and most brown
dwarfs within several tens of AU, implying that the system is devoid of massive companions. Continued RV and astrometric monitoring together with high-contrast imaging can be used to distinguish these scenarios.
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All authors Marvin Morgan, Brendan P. Bowler, Kyle Franson, Lillian Jiang, Eric Gaidos, Quang H. Tran, Jingwen Zhang, Judah Van Zandt, Katie E. Painter, Erik A. Petigura, Darryl Z. Seligman, Adina D. Feinstein, David R. Ciardi, Rocio Kiman, Benjamin J. Fulton, Howard Isaacson, Andrew W. Howard, Stefan Dreizler
Earth and Planetary Astrophysics
Detection and characterization of the temperate super-earth Gliese 48 b
G.Conzo, M.Moriconi and S.A.Corrêa Jr
Gliese 48 is an M3.5V red
dwarf exhibiting significant
magnetic activity and a
stellar rotation period of 51.5 d. In this work, we present a systematic re-analysis of radial velocities (RV) from CARMENES and decade-long HIRES observations, integrated with TESS space-based photometry. We identify a
planet of undetermined composition, Gliese 48 b, with an orbital period $P = 39.6299 \pm 0.29$ d and a minimum mass $M \sin i = 8.11 \pm 1.63 M_{\oplus}$. The planetary nature of the signal is confirmed by its temporal coherence over a 15-year baseline and its achromaticity between visible and near-infrared channels. TESS photometry from Sectors 18, 19, 24, and 25 (218.6 d total baseline, 66,983 cadences) reveals no transit at $P = 39.63$ d (FAP $> 10\%$, BLS). An injection-and-recovery test demonstrates that a 1287 ppm transit signal corresponding to a minimum-radius $1.69 R_{\oplus}$
planet would have been detected with Signal-to-Pink-Noise Ratio SPNR $> 7$, ruling out a transiting geometry with high confidence. The orbital inclination is constrained to $i < 89.3^{\circ}$. With an incident
stellar flux $S_{\rm eff} \approx 0.889 S_{\oplus}$ and bolometric luminosity $L_* = 0.0273 \pm 0.0023 L_{\odot}$, Gliese 48 b lies near the inner edge of the Conservative Habitable Zone and within the Optimistic HZ, making it one of the most astrobiologically compelling temperate Super-Earths orbiting an M-
dwarf.
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High Energy Astrophysical Phenomena
Joint XMM-Newton and NuSTAR Observations of Type I X-ray Bursts from the Dipping Low-Mass X-ray Binary 4U 1323-62
Tugba Boztepe, Tolga Guver, Ersin Gogus et al. (+4 more)
In this study, we report partly simultaneous XMM-Newton and NuSTAR observations of the bursting, dipping low mass X-ray binary, 4U 1323-62 obtained in 2024. 4U 1323-62 is one of the well-known persistent bursters, with bursts occurring roughly every three hours. It is also one of the few sources for which the orbital period is known, and shows dips in X-rays. In this paper, we report the detection of 12 unique bursts with XMM-Newton and NuSTAR, 6 of them observed jointly. We detected two double burst events, one with the NuSTAR and another one observed with both missions. During our observations we detected 10 X-ray dips with a periodicity of 2.942 hours, in line with previous measurements. We also present the results of the time resolved X-ray spectral analysis of the bursts and show the limits on the cooling of the corona heated by the burst emission. We also found a $0.898+/- 0.017 Hz quasi-periodic oscillation (QPO) during the non-bursting and non-dipping times confirming previous detections.
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All authors Tugba Boztepe, Tolga Guver, Ersin Gogus, Diego Altamirano, Julia Speicher, Brian Luff, David R. Ballantyne
Astrophysics of Galaxies
Tracing Radio AGN-Driven Quenching in Post-Starburst Galaxies at Cosmic Noon
Pallavi Patil, Kate Rowlands, Katherine Alatalo et al. (+14 more)
We present a
radio continuum study of photometrically selected
cosmic noon (0.5<z<3) post-starburst
galaxies (PSBs) in the UKIDSS Deep Survey (UDS) field to assess if
radio-mode Active
Galactic Nuclei (AGN) are linked to the quenching of
star formation at
cosmic noon. Our cross-matching using the deep Very Large Array (VLA) imaging at 1.4 GHz results in a mean
radio detection fraction ($f_{det}$) of only 0.8$\%$ for PSBs above a
radio luminosity threshold of $L_{\rm 1.4 GHz} \geq 10^{24}$ W Hz$^{-1}$, increasing to 5$\pm2\%$ for massive PSBs with
stellar masses M$_*>10^{11}$M$_\odot$. Massive PSBs have a comparable detection fraction to that of massive quiescent
galaxies ($f_{det}=8\pm1\%$), and both classes have lower fractions than that of massive
star-forming
galaxies ($f_{det}=13\pm1\%$) in the same field. The
radio luminosities of detected PSBs, ${\rm L}_{1.4}\sim 10^{22.8}-10^{24.9}$W/Hz, exceed those from
star formation by a median factor of 37 indicative of a possible AGN origin. Their compact morphologies ($\lesssim15$ kpc at $z_{med}=1.5$) suggest low-luminosity AGN with less powerful jets. Stacking the undetected PSBs reveals a weak
radio detection ($3.9\sigma$) in the highest mass bin (M$_*>10^{11}$M$_\odot$). In contrast, 1.4 GHz detected quiescent
galaxies have
radio luminosities reaching
radio-loud levels, and a higher prevalence of extended morphologies indicative of large-scale jetted AGN. The AGN contribution is also detected in stacked measurements of quiescent
galaxies. Overall, our results support a short
radio AGN duty cycle for PSBs, characterized by weak
radio jets, suggesting
radio-driven maintenance mode feedback may become important at older ages.
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All authors Pallavi Patil, Kate Rowlands, Katherine Alatalo, Omar Almaini, Vivienne Wild, David Maltby, Rob J. Ivison, Vinod Arumugam, K. Decker French, Timothy Heckman, Mark Lacy, Yuanze Luo, Kristina Nyland, Justin Atsushi Otter, Andreea Petric, Namrata Roy, Maya Skarbinski
Instrumentation and Methods for Astrophysics
Survey Footprint Explorer: A Browser-Based Interactive Tool for Visualizing and Cross-Matching Astronomical Survey Footprints
S. L. Ahad, R. Brilenkov and J. E. Taylor
We present the Survey Footprint Explorer (v2.5.0), a browser-based interactive tool for visualising and comparing the sky footprints of major astronomical imaging surveys. The tool is implemented entirely in client-side JavaScript and requires no server infrastructure, making it immediately accessible from any modern web browser. Thirteen survey footprints are currently included: Euclid DR1, LSST Wide-Fast-Deep, the Nancy Grace Roman HLWAS and HLTDS (full and deep tiers), DESI Legacy Imaging Survey DR9, the Dark Energy Survey (DES), the Subaru Hyper Suprime-Cam survey (HSC), the Kilo-Degree Survey (KiDS), the Ultraviolet Near-Infrared Optical Northern Survey (UNIONS), the eROSITA All-Sky Survey (eRASS1), and the Atacama Cosmology
Telescope Legacy (ACT) survey spanning wavelengths from X-ray to near-infrared and covering footprints from 7.7 deg$^{2}$ to 21,524.4 deg$^{2}$. Survey footprints are encoded as Multi-Order Coverage (MOC) maps and rendered via two complementary views: an interactive globe powered by Aladin Lite v2, and a full-sky equirectangular projection. All MOC intersection calculations, including multi-survey overlap area computation and per-source membership testing, are performed client-side. Users may upload source catalogues in CSV or TSV format and download an augmented version with boolean survey membership columns appended. The link to access the tool is provided at the end of the Summary section.
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