May 2025 (Page 5)

Insights on the Cosmic Origin of Matter from Proton Stability Admir Greljo, Xavier Ponce D’iaz, Anders Eller Thomsen arXiv:2505.18259v1 Announce Type: cross Abstract: We investigate the phenomenology of a model in which the proton is rendered absolutely stable by an IR mechanism that remains robust against unknown quantum gravity effects. A linear combination of baryon number and lepton flavors is gauged and spontaneously broken to a residual $mathbb{Z}_9$ discrete gauge symmetry enforcing a strict selection rule: $Delta B = 0,(mathrm{mod},3)$. Despite its minimal field content, the model successfully accounts for established empirical evidence of physics beyond the SM. High-scale symmetry breaking simultaneously provides a seesawRead More →

Addressing $H_0$ and $S_8$ tensions within $f(Q)$ cosmology Carlos G. Boiza, Maria Petronikolou, Mariam Bouhmadi-L’opez, Emmanuel N. Saridakis arXiv:2505.18264v1 Announce Type: new Abstract: We investigate the viability of $f(Q)$ gravity as an alternative framework to address the $H_0$ and $S_8$ tensions in cosmology. Focusing on three representative $f(Q)$ models, we perform a comprehensive Bayesian analysis using a combination of cosmological observations, including cosmic chronometers, Type Ia supernovae, gamma-ray bursts, baryon acoustic oscillations, and redshift-space distortions. Our results demonstrate that most of these models can yield higher values of $H_0$ than those predicted by $Lambda$CDM, offering a partial alleviation of the tension. In addition, one modelRead More →

Ages and metallicities of quiescent galaxies: confronting broadband ($UVJ$) colours with stellar absorption lines Chloe M. Cheng, Mariska Kriek, Aliza G. Beverage, Martje Slob, Rachel Bezanson, Marijn Franx, Joel Leja, Pavel E. Mancera Pi~na, Katherine A. Suess, Arjen van der Wel, Jesse van de Sande, Pieter G. van Dokkum arXiv:2505.08858v2 Announce Type: replace Abstract: For decades, studying quiescent galaxies beyond $zsim1$ has been challenging due to the reliance on photometric spectral energy distributions, which are highly susceptible to degeneracies between age, metallicity, dust, and star-formation history. Only recently has deep, rest-frame, optical spectroscopy made robust metallicity and age measurements possible, allowing us to empirically assessRead More →

Cosmological feedback from a halo assembly perspective Luisa Lucie-Smith, Hiranya V. Peiris, Andrew Pontzen, Anik Halder, Joop Schaye, Matthieu Schaller, John Helly, Robert J. McGibbon, Willem Elbers arXiv:2505.18258v1 Announce Type: new Abstract: The impact of feedback from galaxy formation on cosmological probes is typically quantified in terms of the suppression of the matter power spectrum in hydrodynamical compared to gravity-only simulations. In this paper, we instead study how baryonic feedback impacts halo assembly histories and thereby imprints on cosmological observables. We investigate the sensitivity of the thermal Sunyaev-Zel’dovich effect (tSZ) power spectrum, X-ray number counts, weak lensing and kinetic Sunyaev-Zel’dovich (kSZ) stacked profiles to haloRead More →

Enhanced Merger Fractions in a Reionization-Era Protocluster Lorraine C. Marcelin, Jaclyn B. Champagne, Feige Wang, Xiaohui Fan, Maria Pudoka, Wei Leong Tee, Yongda Zhu arXiv:2505.18262v1 Announce Type: new Abstract: Mergers play a critical role in galaxy evolution, but their relationship to their surrounding environments is unexplored at high redshift. We investigate the galaxy merger rate among 124 [OIII] emitters at $5.33sigma$ enhancement of the merger fraction amongst all three overdense structures compared to the field. Eleven galaxies are classified as “active mergers” satisfying both merger criteria, all of which occur within the overdensity samples. We conclude that environment affects the merger rates of galaxies atRead More →

Magnetic dynamos powered by white dwarf superficial convection Rom Yaakovyan, Sivan Ginzburg, Jim Fuller, Nicholas Z. Rui arXiv:2505.18257v1 Announce Type: new Abstract: When the effective temperature of a cooling white dwarf $T_{rm eff}$ drops below the ionization limit, it develops a surface convection zone that may generate a magnetic field $B$ through the dynamo mechanism. We revisit the surface dynamo theory systematically using detailed stellar evolution computations, as well as a simple analytical model that tracks the expansion of the convection zone. The magnetic field reaches a maximum of several kG (for a hydrogen atmosphere) shortly after a convection zone is established at a coolingRead More →

Binary mass transfer in 3D — Mass Transfer Rate and Morphology T. Ryu, R. Sari, S. E. de Mink, O. David, R. Valli, J. -Z. Ma, S. Justham, R. Pakmor, H. Ritter arXiv:2505.18255v1 Announce Type: new Abstract: Mass transfer is crucial in binary evolution, yet its theoretical treatment has long relied on analytic models whose key assumptions remain debated. We present a direct and systematic evaluation of these assumptions using high-resolution 3D hydrodynamical simulations including the Coriolis force. We simulate streams overflowing from both the inner and outer Lagrangian points, quantify mass transfer rates, and compare them with analytic solutions. We introduce scaling factors, includingRead More →

The HST Legacy Archival Uniform Reduction of Local Group Imaging (LAURELIN). I. Photometry and Star Formation Histories for 36 Ultra-faint Dwarf Galaxies Meredith J. Durbin, Yumi Choi, Alessandro Savino, Daniel Weisz, Andrew E. Dolphin, Julianne J. Dalcanton, Myoungwon Jeon, Nitya Kallivayalil, Ting S. Li, Andrew B. Pace, Ekta Patel, Elena Sacchi, Evan D. Skillman, Sangmo Tony Sohn, Roeland P. van der Marel, Andrew Wetzel, Benjamin F. Williams arXiv:2505.18252v1 Announce Type: new Abstract: We present uniformly measured resolved stellar photometry and star formation histories (SFHs) for 36 nearby ($lesssim$ 400 kpc) ultra-faint dwarf galaxies (UFDs; $-7.1 le M_V le +0.0$) from new and archival HST imaging.Read More →

GD-1 and the Milky Way Starless Subhalos Raymond G. Carlberg arXiv:2503.13290v2 Announce Type: replace Abstract: Measurements of the GD-1 star stream velocity distribution within $pm$3 degrees of the centerline find a total line of sight velocity spread of 5-6 km/s in the well measured $phi_1=$ [-30, 0] region (Valluri25). The velocity spread is far above the $sim$2-3 km/s of a dissolved globular cluster in a smooth galactic potential. The dynamical heating of the GD-1 star stream is simulated in an evolving model Milky Way potential which includes the subhalos extracted from cosmological CDM and WDM Milky Way-like halos. The model bridges fully cosmological Milky Way-likeRead More →

Minimal Plateau Inflation in light of ACT DR6 Observations Md Riajul Haque, Debaprasad maity arXiv:2505.18267v1 Announce Type: new Abstract: We explore a class of minimal plateau inflationary models constrained by the latest cosmological observations from ACT DR6, Planck 2018, BICEP/Keck 2018, and DESI, collectively referred to as P-ACT-LB-BK18. These models, characterized by a non-polynomial potential, are analyzed using both inflationary and post-inflationary reheating dynamics, and the limits on the viable model parameter space are obtained. Our results show that the minimal model with matter-like post inflationary reheating phase remains consistent with current data at both $1sigma$ and $2sigma$ levels. The inflaton potential’s exponent $n$ andRead More →

Inferring Fireball Velocity Profiles and Characteristic Parameters of Meteoroids from Incomplete Datasets Eloy Pe~na-Asensio, Maria Gritsevich arXiv:2504.10715v3 Announce Type: replace Abstract: Extracting additional information from old or incomplete fireball datasets remains a challenge. To address missing point-by-point observations, we introduce a method for estimating atmospheric flight parameters of meteoroids using metaheuristic optimization techniques. Using a fireball catalog from the European Fireball Network (EN), we reconstruct velocity profiles, meteoroid bulk densities, mass loss rates, and ablation and ballistic coefficients, based on the initial and terminal points’ height, velocity, and mass with the purely dynamical $alpha$-$beta$ model. Additionally, the method’s performance is compared to the Meteorite ObservationRead More →

Identification of Ion-Kinetic Instabilities in Hybrid-PIC Simulations of Solar Wind Plasma with Machine Learning Viacheslav M Sadykov, Leon Ofman, Scott A Boardsen, Yogesh, Parisa Mostafavi, Lan K Jian, Kristopher Klein, Mihailo Martinovi’c arXiv:2505.18271v1 Announce Type: new Abstract: Analysis of ion-kinetic instabilities in solar wind plasmas is crucial for understanding energetics and dynamics throughout the heliosphere, as evident from spacecraft observations of complex ion velocity distribution functions (VDFs) and ubiquitous ion-scale kinetic waves. In this work, we explore machine learning (ML) and deep learning (DL) classification models to identify unstable cases of ion VDFs driving kinetic waves. Using 34 hybrid particle-in-cell simulations of kinetic protons andRead More →

Direct Detection of Dark Photon Dark Matter with the James Webb Space Telescope Haipeng An, Shuailiang Ge, Jia Liu, Zhiyao Lu arXiv:2402.17140v2 Announce Type: replace-cross Abstract: In this study, we propose an investigation into dark photon dark matter (DPDM) within the infrared frequency band, utilizing highly sensitive infrared light detectors commonly integrated into space telescopes, such as the James Webb Space Telescope (JWST). The presence of DPDM induces electron oscillations in both the reflectors and the interior of the detectors. Consequently, these oscillating electrons can emit monochromatic electromagnetic waves with a frequency almost equivalent to the mass of DPDM. By estimating the signal generated byRead More →

Thermal and Turbulence Characteristics of Fast and Slow Coronal Mass Ejections at 1 AU Soumyaranjan Khuntia, Wageesh Mishra arXiv:2505.18296v1 Announce Type: new Abstract: Understanding the thermal and turbulence properties of interplanetary coronal mass ejections (ICMEs) is essential for analyzing their evolution and interactions with the surrounding medium. This study explores these characteristics across different regions of two distinct ICMEs observed at 1 AU, utilizing in-situ measurements from the Wind spacecraft. The polytropic indices, Gamma_e for electrons and Gamma_p for protons) reveal significant deviations from adiabatic expansion, suggesting sustained heating mechanisms within the ICMEs even at 1AU. The effective polytropic index (Gamma_eff) of the magnetic ejectaRead More →

Study on the magnetic field of the ultraluminous X-ray pulsar RX J0209.6-7427 Amar Deo Chandra arXiv:2505.20248v1 Announce Type: new Abstract: RX J0209.6-7427 is an ultraluminous X-ray pulsar (ULXP) having spin period of about 9.3 s. To date, no cyclotron resonance scattering features have been detected in this source, which can enable direct measurement of the magnetic field of the pulsar. We estimate the surface magnetic field of the neutron star in this source using different models and find that the inferred magnetic field lies in the range of $2.4-4 times 10^{13}$G. We study the magnetic field and spin period evolution of the source using existingRead More →

Galaxies OBserved as Low-luminosity Identified Nebulae (GOBLIN): a catalog of 43,000 high-probability dwarf galaxy candidates in the UNIONS survey Nick Heesters, David Chemaly, Oliver M"uller, Elisabeth Sola, S’ebastien Fabbro, Ashley Ferreira, Alan W. McConnachie, Eugene Magnier, Michael J. Hudson, Kenneth Chambers, Franc{c}ois Hammer, Ruben Sanchez-Janssen arXiv:2505.18307v1 Announce Type: new Abstract: The detection of low surface brightness galaxies beyond the Local Group poses significant observational challenges, yet these faint systems are fundamental to our understanding of dark matter, hierarchical galaxy formation, and cosmic structure. Their abundance and distribution provide crucial tests for cosmological models, particularly regarding the small-scale predictions of $Lambda$CDM. We present a systematic detectionRead More →

A neural network for estimating compact binary coalescence parameters of gravitational-wave events in real time Sushant Sharma Chaudhary, Gianmarco Puleo, Marco Cavaglia arXiv:2505.18311v1 Announce Type: cross Abstract: Low-latency pipelines analyzing gravitational waves from compact binary coalescence events rely on matched filter techniques. Limitations in template banks and waveform modeling, as well as nonstationary detector noise cause errors in signal parameter recovery, especially for events with high chirp masses. We present a quantile regression neural network model that provides dynamic bounds on key parameters such as chirp mass, mass ratio, and total mass. We test the model on various synthetic datasets and real events from LIGO-Virgo-KAGRARead More →

Unveiling compact planetary nebulae: Broad-band survey analysis and LAMOST confirmation L. A. Guti’errez-Soto, M. Bel’en Mari, W. A. Weidmann, F. R. Faifer arXiv:2505.18308v1 Announce Type: new Abstract: Planetary nebulae (PNe) are pivotal for advancing our knowledge of stellar evolution and galactic chemical enrichment. Recent progress in surveys and data analysis has revolutionized PN research, leading to the discovery of new objects and deeper insights into their properties. We have devised a novel photometric selection method, integrating GAIA and Pan-STARRS photometry, to identify compact PN candidates. This approach utilizes color-color diagrams, specifically (G-g) versus (GBP-GRP) and (G-r) versus (GBP-GRP), as primary criteria for candidate selection. TheRead More →

Large Language Models as Autonomous Spacecraft Operators in Kerbal Space Program Alejandro Carrasco, Victor Rodriguez-Fernandez, Richard Linares arXiv:2505.19896v1 Announce Type: cross Abstract: Recent trends are emerging in the use of Large Language Models (LLMs) as autonomous agents that take actions based on the content of the user text prompts. We intend to apply these concepts to the field of Control in space, enabling LLMs to play a significant role in the decision-making process for autonomous satellite operations. As a first step towards this goal, we have developed a pure LLM-based solution for the Kerbal Space Program Differential Games (KSPDG) challenge, a public software design competitionRead More →

Filling fractions for the formation of nuclear pasta in neutron stars: semiclassical vs liquid-drop predictions Nikolai N. Shchechilin, Nicolas Chamel, Andrey I. Chugunov arXiv:2505.18309v1 Announce Type: new Abstract: Historically, a sequence of nuclear pasta shapes was predicted to appear in the deepest region of the inner crust of a neutron star within the compressible liquid-drop picture, when the filling fraction $u$ exceeds some threshold values. However, later calculations showed that these values depend on the details of the liquid-drop model. Here we investigate the existence of pasta in neutron stars within the semiclassical extended Thomas-Fermi approach using various generalized Skyrme functionals. The filling fractions forRead More →