Space and Astronomy
Stars, galaxies, planets, and the instruments pointed at them.
P. Priolet, J. -C. Augereau, J. Milli, A. Matter, B. Lopez, H. Beust, J. Varga, P. Boley, W. -C. Danchi, L. Foteini, T. Henning, M. Houllé, M. Letessier, F. Millour, J. Scigliuto, G. Weigelt, S. Wolf, O. Absil, J. -P. Berger, Y. -I. Bouarour, G. Bourdarot, D. Defrère, C. Desgrange, J. -B. Le Bouquin, D. Iglesias, T. A. Stuber, P. Berio, F. Bettonvil, P. Cruzalèbes, M. Heininger, J. W. Isbell, S. Lagarde, A. Meilland, R. Petrov, S. Robbe-Dubois
Earth and Planetary Astrophysics · about 79 min · about 12,226 words · posted 2026-09-24 · CC BY 4.0 · 17 figures, 7 tables, 17 equations
- Published in Astronomy & Astrophysics, 713, A51
- 93% prose
- Has a DOI
- Filed in 2 fields
- Openly licensed
Abstract
Context: Hot exozodiacal dust has been detected around approximately 20% of nearby main-sequence stars, indicating that it is a common feature of extrasolar planetary systems. However, its spatial distribution and grain properties remain poorly understood. Aims: We aim to show that the spatial distribution of hot dust around beta Pictoris, an iconic planetary system with two known planets and a population of exocomets, can be constrained through a detailed analysis of optical long-baseline interferometry data. Methods: We obtained L-band observations at approximately 3.5 microns of beta Pictoris with MATISSE at the VLTI. We developed a method to assess correlations in the visibility measurements by estimating the full data covariance matrix, and modeled the circumstellar emission with geometric brightness distributions. Results: We detect circumstellar emission around beta Pictoris consistent with hot exozodiacal dust. Modeling the emission with and without accounting for data correlations demonstrates their significant impact on the inferred dust properties. The best-fit model reveals a compact (approximately 0.05 au), highly inclined dust structure near the sublimation radius, misaligned by approximately 60 degrees on the sky with respect to the extended edge-on outer disk. It contributes approximately 4%-7.5% of the total flux at 3.4 microns and is composed of submicron-sized grains. The data are also compatible with an additional dust component near 1 au. Conclusions: For beta Pictoris, the two-decade-old paradigm placing hot exozodiacal dust near the sublimation radius and consisting of submicron-sized grains finds observational support in the detailed analysis of MATISSE data. The misalignment with the known debris disk further supports a link to exocometary activity.
arXiv:2609.29783 Full text (HTML)
B. Hudson, L. I. Gurvits, D. J. D'Orazio, C. Tiede, T. M. Eubanks, E. Mooij
High Energy Astrophysical Phenomena · about 71 min · about 11,066 words · posted 2026-09-08 · CC BY 4.0 · 10 figures, 2 tables, 38 equations
- Accepted for publication
- 92% prose
- Filed in 2 fields
- Openly licensed
- 22 pages
Abstract
Evidence of a gravitational wave background suggests the existence of a population of sub-parsec supermassive black hole binaries (SMBHBs), with characteristic angular separations on the order of 1-10 $μ$as. Spaceborne extensions of Very Long Baseline Interferometry (VLBI) and the next generation ground arrays introduce the possibility of directly imaging these SMBHBs. In this work, a binary Spectral Energy Distribution (SED) model is used to predict the detectability of SMBHBs with ground and spaceborne VLBI. We consider the Black Hole Explorer (BHEX), a proposal for a spaceborne VLBI mission, as our primary case study. We explore the detectable SMBHB parameter space and identify distinguishable binary signatures that could exist in the visibility domain. We find that for a flux-density-limited sample, ground array observations are more effective at detecting a wider region of the binary parameter space, with $M_\mathrm{tot} \gtrsim 10^9$ solar mass systems detectable out to redshift, $z=0.075$ and beyond. Conversely, inclusion of a spaceborne element such as BHEX, offering finer angular resolution ($\sim6\,μ$as) and sampling of the (u,v) plane not limited by Earth rotation synthesis, will provide significant benefits in constraining binary properties, resulting in improvements in characterisation of the separation and position angle of SMBHBs by a factor of $\sim4$. Near-future ground and/or spaceborne VLBI may achieve the first direct observation of a SMBHB, contributing significantly to multi-messenger studies of such systems with pulsar timing arrays and observations across the electromagnetic spectrum.
arXiv:2609.08704 Full text (HTML)
Pavel E. Mancera Piña, Justin I. Read, Jorge Sarrato-Alós, Claudia Muni
Astrophysics of Galaxies · about 80 min · about 12,429 words · posted 2026-09-21 · CC BY 4.0 · 13 figures, 16 equations
- Accepted for publication
- 92% prose
- Filed in 2 fields
- Openly licensed
- 12 pages
Abstract
Two of the most prominent small-scale challenges to the cold dark matter (CDM) paradigm are the cusp-core and diversity-of-rotation-curves problems. The former concerns the shallow inner DM density profiles inferred for many galaxies compared with the cusps predicted by collisionless CDM, while the latter concerns the wider range of inner DM densities and rotation curve shapes inferred observationally than hydrodynamical simulations traditionally reproduce. Robust observational constraints on DM core sizes and halo densities are therefore essential for testing both the nature of DM and the impact of galaxy formation processes. We analyse the inner DM distribution of a curated sample of 48 gas-rich galaxies and 8 Milky Way gas-poor satellites, spanning 6 orders of magnitude in $M_\ast$. We find substantial scatter in DM core sizes and degrees of coreness, with both cuspy and cored haloes occurring over a broad $M_\ast$ range. The cores are energetically consistent with stellar feedback, requiring modest supernova energy coupling efficiencies of order $0.1-1\%$. Comparisons with the NIHAO, FIRE-2, and EDGE simulations reveal broad agreement in the inner DM densities and logarithmic slopes of observed and simulated galaxies. The main residual differences concern the steep slopes of some massive simulated galaxies and differences in SHMRs. Using a rotation-curve diversity diagnostic from previous work, we find that extreme discrepancies with simulations are absent from our curated sample and largely attributable to uncertain kinematics or baryonic mass distributions. Within the scope of our analysis, we find no evidence of a systematic inner-density tension between our galaxy sample and current $Λ$CDM hydrodynamical simulations. Together with the modest energetic requirements for core formation, this substantially alleviates the cusp-core and diversity-of-rotation-curves problems.
arXiv:2609.25220 Full text (HTML)
Barnabás Barna, Mridweeka Singh, Lindsey A. Kwok, Saurabh W. Jha, R. Dastidar, Conor Larison, Alexei V. Filippenko, J. P. Anderson, Jennifer E. Andrews, Moira Andrews, G. C. Anupama, Prasiddha Arunachalam, Katie Auchettl, Dominik Bánhidi, K. Azalee Bostroem, Thomas G. Brink, Régis Cartier, Ping Chen, T. -W. Chen, Collin T. Christy, David A. Coulter, Sofia Covarrubias, Kyle W. Davis, Connor B. Dickinson, Yize Dong, Joseph Farah, Andreas Flörs, Ryan J. Foley, Noah Franz, Christoffer Fremling, Lluís Galbany, Anjasha Gangopadhyay, Aarna Garg, Elinor L. Gates, Or Graur, Mariusz Gromadzki, Daichi Hiramatsu, Emily Hoang, D. Andrew Howell, Brian Hsu, Joel Johansson, Arti Joshi, Lordrick A. Kahinga, Ravjit Kaur, Sahana Kumar, Piramon Kumnurdmanee, Hanindyo Kuncarayakti, Chang Liu, Keiichi Maeda, Kate Maguire, Bailey Martin, Curtis McCully, Darshana Mehta, Luca M. Menotti, Anne J. Metevier, A. A. Miller, Kuntal Misra, Erika Mochnács, T. E. Müller-Bravo, Megan Newsome, Estefania Padilla Gonzalez, Kishore C. Patra, Jeniveve Pearson, Anthony L. Piro, Abigail Polin, Aravind P. Ravi, Armin Rest, Nicolas Meza Retamal, O. M. Robinson, César Rojas-Bravo, Devendra K. Sahu, David J. Sand, Brian P. Schmidt, Steve Schulze, Michaela Schwab, Manisha Shrestha, Matthew R. Siebert, Sunil Simha, Nathan Smith, Jesper Sollerman, Shubham Srivastav, Bhagya M. Subrayan, Tamás Szalai, Kirsty Taggart, Rishabh Singh Teja, Jacco H. Terwel, Samaporn Tinyanont, Stefano Valenti, József Vinkó, Aya L. Westerling, J. Craig Wheeler, Yi Yang, WeiKang Zheng
High Energy Astrophysical Phenomena · about 55 min · about 8,502 words · posted 2026-09-23 · CC BY 4.0 · 7 figures, 4 tables, 1 equations
- Accepted for publication
- 97% prose
- Filed in 2 fields
- Openly licensed
- 11 pages
Abstract
We present an abundance tomography analysis of SN 2024pxl, an intermediate luminosity Type Iax supernova ($M_{r}=-16.82 \pm 0.19$ mag), with the most-detailed follow-up in the Type Iax subclass to-date. As one of the few intermediate luminosity Type Iax objects, SN 2024pxl may link the two extremes of the peculiar thermonuclear supernova subclass. To test this hypothesis, we analyze its spectral evolution through the first 100 days after the explosion and aim to probe the structure of its ejecta. We conduct an abundance tomography analysis using synthetic spectra produced with the one dimensional radiative transfer code TARDIS. The fit of the spectral time series provides a radial scan of physical properties and probes the stratification of chemical elements throughout most of the SN ejecta. The observed spectral evolution is well fit with the final model, similar to the general predictions of the pure deflagration scenarios, but significant modifications are required in the density function of the inner ejecta and in the chemical profiles of the outermost regions. The constrained physical characteristics, such as the photospheric velocities and the time of maximum light, are also consistent with other SNe~Iax. Despite their small number, intermediate luminosity Type Iax SNe are not outliers in the subclass but demonstrate the continuous nature of SNe Iax through their luminosity range. Following this observation, we argue that all SNe~Iax share the same progenitor and explosion origin.
arXiv:2609.28712 Full text (HTML)
Chih-Chun Hsu, Christopher A. Theissen, Adam J. Burgasser, Adam C. Schneider, Christian Aganze, Aaron M. Meisner, Jonathan Gagné, Nicolas Lodieu, Zenghua Zhang, Genaro Suárez, Eileen C. Gonzales, Jacqueline K. Faherty, Jason J. Wang, Stanimir Metchev, Dan Caselden, Michael C. Cushing, Roman Gerasimov
Solar and Stellar Astrophysics · about 54 min · about 8,421 words · posted 2026-09-23 · CC BY 4.0 · 5 figures, 6 tables
- Accepted for publication
- Filed in 3 fields
- 89% prose
- Openly licensed
- 21 pages
Abstract
Galactic archaeology relies on stellar kinematics and chemical abundances to identify various stellar populations and associations. With JWST, Galactic archaeology of ancient metal-poor brown dwarfs is now possible through high-sensitivity, medium-resolution spectroscopy. We present the first metal-poor brown dwarf radial velocity (RV) survey using JWST/NIRSpec G395H spectra ($λ/Δλ\sim$ 3,000) for a sample of 23 LTY dwarfs across a wide range of temperatures and metallicities. We introduce a forward-modeling framework to measure robust RVs for brown dwarfs by focusing on the CO fundamental band at $\sim$4.5 $μ$m. By comparing to sources with existing high-resolution RV measurements, we demonstrate that G395H RVs can achieve a systematic uncertainty of 5 km s$^{-1}$, sufficient to examine their Galactic space motions. We identify kinematic members of the Milky Way's thin disk, thick disk, and halo populations in this sample. We also confirm WISE J155349.98$+$693355.2 as likely associated with the Gaia-Enceladus merger remnant, and 2MASS J05325346$+$8246465 is likely associated with the Thamnos stream. Our study systematically demonstrates that JWST G395H spectroscopy can provide robust RVs in addition to detailed chemical abundances, necessary for Galactic archaeology studies. Future discoveries and characterization of brown dwarfs associated with Galactic halo substructures and streams will enable a stringent test of stellar/substellar formation and evolutionary models for diverse metallicities.
arXiv:2609.28746 Full text (HTML)