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Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.EP

Tracing the main belt origins of S-complex near-Earth objects: From space mission targets to meteorite sources

P. N. Simon, P. Vernazza, M. Marsset, M. Brož, R. P. Binzel, F. DeMeo, C. A. Thomas, L. Jorda et al.

Context. Space missions to near-Earth objects (NEOs) provide unique opportunities to study and characterise their physical and compositional properties. Interpreting these results requires knowledge of their provenance, i.e. their source family in the main asteroid belt. Aims. We aim to identify the family sources of six S-complex NEOs visited or soon to be visited by space missions, and to investigate the size-dependent orbital behaviour of the broader S-complex NEO population using the MITHNEO…

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astro-ph.GAhep-ph

Occam's Razor and a Three-Family Ultralight Fermionic Dark Matter Model

Fabian Hernandez-Gutierrez, Juan Barranco

Inspired by the three generations in the Standard Model, we propose that dark matter particles are simply three non-interacting ultralight fermions. This model is tested at galactic scales with the SPARC catalog of rotational velocity curves. This is done by modeling the dark matter halo as the self-gravitating configuration of three gravitationally coupled fermion species. This configuration is capable of forming more complex rotational curves which gives it flexibility to describe more complex…

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astro-ph.IMastro-ph.HEastro-ph.SR

SPECULATE: A synthetic spectral library, emulator and fitting package for accretion disc winds -- Infrastructure and application to CVs

Austen G. W. Wallis, Christian Knigge, James H. Matthews, Knox S. Long, Madeleine-Mai Ward, Stuart A. Sim, Adam B. Hill, Amin Mosallanezhad et al.

Disc winds are critical components of accreting astrophysical systems and their observations can yield a wide variety of spectral line profiles. Yet, inferring disc wind parameters remains challenging: the underlying parameter spaces are high-dimensional and degenerate, while the radiative-transfer simulations are imperfect and computationally expensive. This paper tackles bridging this gap. Here, we present 'Speculate', an open-source framework for rapidly emulating and fitting observations wit…

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astro-ph.GA

The universal thickness of mid-infrared bubbles

Michael M. Schulreich, A. Beate C. Patzer

Several hundred ring-like structures seen at $8μ$m in the Spitzer GLIMPSE surveys share a uniform morphology: the shell thickness $ΔR$ is a nearly constant fraction of the outer radius $R$, $ΔR/R\sim0.3$, across a factor of 40 in size and all exciting spectral types. This invariance is unexplained. We ask what sets this thickness and whether its near-constancy is physical or a measurement artifact. We derive analytic constraints on the location, temperature, and heating of the emitting grains, a…

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astro-ph.IM

A Classifier Framework for ALMA Bandpass Calibration Anomalies

Ci Xue, Brian S. Mason, Gazi A. Rakib, Tristan Ashton, Jeff M. Phillips, Ignacio Toledo, Ryan A. Loomis, Ilsang Yoon et al.

Bandpass calibration corrects instrumental responses across observing frequencies in interferometric radio observations, so the measured calibration solutions inherently contain spectral variation that varies with instrumental configurations and noise conditions. However, some signals contain anomalies, which if not caught can lead to poorly constructed science products. Observatory pipelines often use scalar metrics with individual, linear decision boundaries. Constructing a simple parametric m…

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astro-ph.HEastro-ph.GA

A spatially resolved view of Fast Radio Burst host metallicities with Integral-field Spectroscopy

Sunil Simha, Hsiao-Wen Chen, Wen-fai Fong, Sarah Hughes, Yuxin Dong, J. Xavier Prochaska, Nicolas Tejos, Tarraneh Eftekhari et al.

Magnetar sources are the leading theory for Fast Radio Burst (FRB) progenitors. If magnetars are indeed the dominant sources, we may thus expect any metallicity preference for magnetar formation to be reflected in the FRB site in host galaxies. Here, we leverage Integral Field Unit (IFU) spectroscopy to spatially resolve gas-phase metallicity distribution in five FRB host galaxies: FRB 20240210A, FRB 20240312D, FRB 20250227A, FRB 20211127I, and FRB 20250316A, at $z < 0.05$, including the FRB sit…

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astro-ph.HE

Investigating X-ray Emission from Radio-detected Broad- and Narrow-line Seyfert 1 Galaxies

Minhua Zhou, Minfeng Gu, Lei Xu, Mai Liao, ZhengXue Chang

Context: This paper presents a study of the X-ray emission for a sample of radio-detected (RD-) broad- and narrow-line Seyfert 1 galaxies (NLS1s and BLS1s). Aims: To investigate the X-ray emission properties of early-stage accretion activity or early jets in NLS1s. Methods: By fitting XMM-Newton X-ray spectra and combining with multi-band data from SDSS and FIRST, we conducted a statistical comparative study on the X-ray emission and multi-band correlations of NLS1s and BLS1s. Results: NLS1s and…

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astro-ph.GA

Complex Organic Molecules in Protostars with ALMA Spectral Surveys (COMPASS) VII. First interstellar detection of fully deuterated methanol

A. Belloche, S. Spezzano, A. Coutens, M. N. Drozdovskaya, J. K. Jørgensen, J. -E. Lee, A. L. Plunkett, D. Harsono et al.

There have been no robust identifications of fully deuterated methanol, CD3OD, in the interstellar medium (ISM) to date. Our goal is continue the search for CD3OD in star-forming regions to determine the deuteration pattern of methanol and set constraints on the deuteration process. We used a sensitive imaging spectral survey of the protostellar system IRAS4A in the NGC1333 molecular cloud performed as part of the large program carried out with the Atacama Large Millimeter/submillimeter Array (A…

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astro-ph.GA

Multiple H I 21-cm absorbers towards blazar PKS 1158+007

Abhisek Mohapatra, R. Srianand, R. Dutta

We report an interesting line of sight towards the blazar PKS 1158+007 (J1201+0028) ($z_{\rm em}$ = 1.369), revealing the rare detection of two intervening HI 21-cm absorption systems within a narrow redshift interval ($Δz \sim 0.04$) using the MeerKAT radio telescope. The stronger absorber at $z_{\rm abs}$ $=0.5653$ ($\intτdv = 1.31\pm0.04$ \kms) is associated with a strong MgII $\lambda2796$ system seen in the Sloan Digital Sky Survey (SDSS) and Dark Energy Spectroscopic Instrument (DESI) spec…

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astro-ph.HEastro-ph.IM

Chana: A GPU-Accelerated AMR GRRMHD Code

Tianshu Wang

This paper presents Chana, a GPU-accelerated, block-structured adaptive-mesh code for general relativistic magnetohydrodynamics, multigroup M1 neutrino transport, and dynamical spacetime evolution using the Z4c formulation. Each physical module uses independently selected spatial discretizations and ghost-zone widths to balance accuracy and computational cost. Stiff radiation-matter interactions are treated implicitly, with Jacobians calculated analytically from the chain-rules. The code is writ…

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astro-ph.HEnucl-th

Radial Modes of Hot Neutrino-Trapped Hybrid Stars

Peter B. Rau, Andrea Sabatucci, Armen Sedrakian

We study the fundamental radial oscillation mode of hot hadronic and hybrid stars under conditions relevant to proto-neutron stars and neutron-star merger remnants. The stellar backgrounds are constructed from finite-temperature equations of state with a covariant density functional for hadronic matter and three-flavor 2SC quark matter at high density. We consider two isentropic configurations in both neutrino-transparent matter and with trapped electron neutrinos at fixed electron-lepton fracti…

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astro-ph.EP

Exploring the ultrahot Neptune LTT 9779 b with CRIRES+. Non-detection of helium transmission spectra and detection of H$_2$O on the dayside

S. Liu, F. Yan, L. Nortmann, B. Guo, D. Cont, F. Lesjak, D. Shulyak, A. Reiners et al.

Ultrahot Neptunes reside in the most extreme irradiation regime of the hot Neptune desert and remain challenging targets for atmospheric characterization because of their low planet-to-star flux ratios. We present high-resolution transit and dayside thermal emission spectroscopy of the ultrahot Neptune LTT 9779 b obtained with CRIRES$^+$, to probe atmospheric escape and dayside molecular emission. No significant absorption is detected in the metastable He I $λ1083$ nm triplet during transit, yie…

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astro-ph.GAastro-ph.CO

Hierarchical Black Hole Mergers at High Redshift: Predictions for LISA and LGWA from SEEDZ

Daxal H. Mehta, Lewis R. Prole, John A. Regan, Rüdiger Pakmor, Sophie Koudmani, Ricarda S. Beckmann, Michael Tremmel, John H. Wise et al.

We investigate the hierarchical assembly of black holes (BHs) in the early Universe using the next-generation SEEDZ cosmological zoom-in simulations. Our suite follows two independent regions (\textsc{Rarepeak} and \textsc{Normal1}) evolved with three BH feedback prescriptions: no feedback (NoFB), weak feedback (WeakFB), and standard thermal isotropic feedback (FidBH). Focusing on BH mergers at $z \geq 10$, we explore merger-driven BH growth and detectability with next-generation gravitational-w…

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astro-ph.GA

Spectroscopic Confirmation of the Milky Way Satellites Boötes V and Leo Minor I and the LMC Satellite DELVE 2: Three Small Ultra-Faint Dwarf Galaxies

W. Cerny, M. Geha, J. D. Simon, T. S. Li, A. B. Pace, R. P. van der Marel, N. Kallivayalil, A. P. Ji et al.

We present the first multi-object spectroscopy of Boötes V, Leo Minor I, and DELVE 2 -- three small (20 pc $\le r_{1/2}\le$ 26 pc), ultra-faint ($-3.2\le M_V\le-2.1$) stellar systems in the outer Galactic halo (71 kpc $\le D_\odot\le$ 102 kpc) with heretofore ambiguous classifications. Leveraging at least two epochs of Keck/DEIMOS or Magellan/IMACS observations targeting each satellite, we identify 13, 7, and 7 spectroscopic members in the three systems, respectively. We tentatively resolve a $σ…

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astro-ph.EPastro-ph.IM

Enhancing the Interpretability of Radial Velocity Analysis Using Leave-one-out Cross-validation

Matthew C. Nixon, Ritvik Basant, Rafael Luque, Luis Welbanks, Pierrot Lamontagne

Radial velocity (RV) observations are reaching increasingly high precision, enabling the targeting of low-amplitude signals. Assessing results obtained at the limits of our capabilities requires understanding the relationship between data, models and inference. Leave-one-out cross-validation (LOO-CV) has become an increasingly popular tool for interpretable model criticism in astronomical data analysis. In this work, we demonstrate how LOO-CV can provide insight into the RV analysis of exoplanet…

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astro-ph.GAastro-ph.EPcond-mat.mes-hallphysics.comp-ph

Molecular hydrogen formation on dust: The impact of gas-dust drift on formation efficiency

Stefan Reissl, Simon C. O. Glover, Ralf S. Klessen, Liam S. Morrissey, Mordecai-Mark Mac Low

Molecular hydrogen is predominantly formed on dust-grain surfaces in the interstellar medium, where relative gas-dust motion can arise in dynamically active environments. While the dependence of H$_2$ formation on grain temperature and surface properties is well studied, the impact of gas-dust drift has received little attention. We investigate how gas-dust drift modifies H$_2$ formation, focusing on the competition between the drift-enhanced H-atom collision rate and reduced sticking at higher…

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astro-ph.GA

DIGging into HII regions: the role of ionizing photon leakage and spectral hardening in coupling HII regions and diffuse ionized gas

Dalya Baron, Kathryn Kreckel, Gwen C. Rudie, Karin M. Sandstrom, Alberto D. Bolatto, Guillermo A. Blanc, Oleg V. Egorov, Eva Schinnerer et al.

The optical emission-line ratios of star-forming galaxies are broadly understood in the framework of photoionization, yet some systematic trends remain unexplained. Using 50--100 pc resolution PHANGS-MUSE observations of 19 nearby galaxies, we investigate how escaping ionizing radiation couples HII regions to the diffuse ionized gas (DIG), analyzing thousands of HII regions and DIG sightlines. HII regions and the DIG form a continuous sequence across standard line-ratio diagnostic diagrams (e.g.…

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astro-ph.EPastro-ph.SR

Discovery of a second-generation planet candidate accreting onto a white dwarf

Jamie T. Williams, Boris T. Gänsicke, Nicholas C. Stone, Detlev Koester, Benjamin D. R. Davies, Christopher Tong, David J. Wilson, Snehalata Sahu et al.

Many white dwarfs accrete the debris of disrupted planetary bodies, detected in the form of metal-enrichment in their atmospheres, dusty or gaseous circumstellar discs, and photometric transits from debris. The composition of accreted debris has been shown to be diverse yet overall closely resembles Solar System bodies. We report the discovery of a white dwarf accreting material that is unlike any Solar System object. The atmosphere of HS 0209+0832 is strongly enriched in trans-iron elements inc…

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hep-phastro-ph.HEhep-exhep-thquant-ph

Magnus: neutrino oscillation probabilities for any Hermitian Hamiltonian, any number of flavors, and any matter profile

Mauricio Bustamante

Interpreting neutrino oscillation measurements requires computing the probability that a neutrino born with one flavor is detected with another. In vacuum and in matter of constant density, this probability has exact formulas. Where the density varies along the path, as in the Earth, the Sun, or a supernova, it does not. There, the usual approaches either replace the profile by constant-density steps, whose error falls only as the square of their width, or integrate the evolution equation with a…

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astro-ph.HEphysics.plasm-ph

Power-Law Injection Spectrum from an Ensemble of Reconnecting Current Sheets

Omar French

A collisionless, low-$β$ plasma undergoing strong sub-Alfvénic turbulence is expected to form a broad hierarchy of reconnecting current sheets immersed in a strong guide magnetic field. If the reconnecting field strength of a sheet scales with its length as a power law of index $κ$, and the number of sheets per unit interval of sheet length decreases as a power law of index $x$, the current-sheet ensemble injects nonthermal particles with a power-law energy spectrum $\propto γ^{-s}$, where $s =…

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astro-ph.HEastro-ph.GAastro-ph.SR

Uncovering the Physical Origins of Black Holes in the Milky Way for Astronomical Surveys

Ilia Kiato, Pierson Lipschultz, Vicky Kalogera, Jeff J. Andrews, Max M. Briel, Abhishek Chattaraj, Seth Gossage, Philipp M. Srivastava et al.

The observational landscape of stellar-mass black holes (BHs) in the Milky Way is expanding beyond X-ray binaries, with Gaia DR4 and Roman expected to open new windows onto BH populations. We use the binary population synthesis framework POSYDON to predict the present-day Galactic BH population and connect it to its evolutionary origins. We test the robustness of these predictions to uncertainties in binary evolution and BH formation, including core-collapse mechanisms, natal kicks, common-envel…

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astro-ph.EPastro-ph.IM

Detecting multiple planets in Gaia data using Bayesian model selection

Emmanuel J. Greenfield, James E. Owen

Gaia will soon provide a census of cold giant planets. However, an astrometric signal contains the superimposed reflex motion of all companions, so planetary signals cannot be treated individually. We therefore investigate Gaia's planet-detection capabilities for 1-planet and 2-planet systems, with special attention to systems near 2:1 mean-motion resonance. Gaia can detect 2-planet systems, although the lower-S/N planet requires a higher S/N threshold, especially when the outer planet is more m…

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astro-ph.SR

Unlocking new information in stellar circular polarisation with second-order least-squares deconvolution

Oleg Kochukhov

Least-squares deconvolution (LSD) is the standard technique for measuring stellar magnetic fields from circular polarisation spectra. It rests on the weak-field approximation and yields the longitudinal field alone. We aim to extend LSD beyond the weak-field limit and interpret departures from a linear field response in terms of the field modulus. The Stokes V absorption coefficient is expanded in odd wavelength derivatives of the intensity profile, with coefficients given by the Zeeman pattern…

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astro-ph.COastro-ph.GA

And Then There WEre Baryons (ATWEB): The Baryon Budget of the Universe in Halos and the IGM over 13 Billion Years of Cosmic Time

Mohammadreza Ayromlou, G. Mark Voit, Thomas H. Reiprich, Cristiano Porciani, Dominique Eckert

Observations of the local Universe show that, except in the most massive galaxy clusters, the baryon fraction within halos falls below the cosmic mean. This deficit can be characterized using the previously established closure radius, the halocentric distance within which the enclosed baryon fraction reaches the cosmic value. Using the TNG, EAGLE and SIMBA simulations, we examine how, when, and on what scales the baryonic and dark matter distributions diverge. At z=0 less than 30% of cosmic bary…

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astro-ph.GAastro-ph.SR

Cracking open the "dragon egg": ALMA 1.3mm observations of a compact, young high-mass core candidate at 30mas resolution

A. T. Barnes, J. D. Henshaw, Á. Sánchez-Monge, P. Caselli, I. Jiménez-Serra, J. E. Pineda, K. Immer, M. De Simone et al.

Massive prestellar cores are a central assumption of core-accretion models of high-mass star formation, yet convincing observational examples remain rare. The "dragon egg" (C2c1a) core in the infrared-dark cloud G028.37+00.07 has been proposed as a promising compact high-mass core candidate. We present new ALMA Band 6 observations at $0.035''$-$0.078''$ ($\sim175$-400 au at 5 kpc), providing one of the most stringent high-resolution tests of such a candidate. The region resolves into multiple fr…

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astro-ph.IMastro-ph.HE

Optimal Photon Counting with Fast, Low Noise Astronomical Imagers

Jack T. Dinsmore, Christopher Layden, Roger W. Romani, Vera L. Berger, Kevin B. Burdge, Geoffrey Mo, Deepto Chakrabarty, Emma T. Chickles et al.

Measuring rapid astrophysical phenomena requires many short exposures, which suffer from repeated read noise. A variety of recent technologies are achieving sub-electron read noise, which enable rapid time-domain studies of faint sources. These data can be analyzed with traditional methods, but the ability to resolve individual electrons enables a new class of more precise, photon-counting techniques. We present a photon-counting method for sub-electron read noise detectors which delivers optima…

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astro-ph.EPastro-ph.GA

First Direct Identification of a Multi-Star Microlens System Hosting a Planet

Sean K. Terry, David P. Bennett, Jean-Philippe Beaulieu, T. Dex Bhadra, Aparna Bhattacharya, Joshua W. Blackman, Ian A. Bond, Andrew A. Cole et al.

Nearly 25 years have passed since gravitational microlensing delivered its first exoplanet discoveries. The relative proper motion between lens and source systems allows them to be resolved as they separate on the sky over many years. This enables scientists to study light coming directly from the lenses and place tight constraints on the physical properties of these planetary systems. In this paper we present an analysis of high angular resolution images of the microlensing target OGLE-2006-BLG…

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astro-ph.SRastro-ph.EP

Production of White Dwarf Debris Disks from Planetary Collisions and Poynting-Robertson Drag

Fred C. Adams, Konstantin Batygin

This paper explores the production of debris disks around white dwarfs, which are observed to experience frequent pollution events. In this scenario, planetary collisions occur just outside the surface of a highly evolved AGB star, after the end of its mass loss phase, as it starts its transition into a white dwarf. The collisions vaporize a fraction of the planetary material, which subsequently expands, cools, nucleates droplets, and condenses into rocky bodies with characteristic size of order…

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astro-ph.GAgr-qc

Probing departures from Schwarzschild geometry with the S301 star and kilometre-baseline interferometry

Rodrigo P. Silva, Alexandre C. M. Correia, Paulo J. V. Garcia

The S301 star reaches a pericentre one tenth that of S2, opening a new regime for probing black-hole spin and departures from Schwarzschild. We develop a post-Newtonian secular Hamiltonian framework for bound geodesics in stationary, axisymmetric spacetimes and compute the maximum projected astrometric deviation over one orbit. At the expected GRAVITY+ precision, S301 can probe several nonrotating geometries and sizeable spin-induced deviations, while kilometre-baseline interferometry can probe…

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astro-ph.GA

Unveiling the Origins of the Molecular Gas Reservoirs in Recently Quenched Massive Galaxies

E. Savitch, D. Narayanan, D. J. Setton, K. E. Whitaker, R. Bezanson, E. Cenci, R. Davé, V. R. D'Onofrio et al.

Observations of quenched galaxies across cosmic time have revealed systems containing substantial molecular gas reservoirs, challenging the traditional picture of gas-poor, red and dead galaxies. Using the Simba cosmological simulation, we investigate three possible hypotheses for the origin of molecular gas-rich quenched systems: (i) quiescence is temporary and the galaxy will rejuvenate, (ii) molecular gas masses are overestimated due to an underestimated CO-to-H$_2$ conversion factor, or (iii…

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