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Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.SRastro-ph.GA

Unresolved triple systems in the aged open cluster Trumpler 19: Discovery, confirmation, and implications

D. Minniti, R. K. Saito, V. D. Ivanov, C. O. Obasi, P. W. Lucas, J. G. Fernández-Trincado, J. Alonso-García, E. R. Garro et al.

It is difficult to identify unresolved triple and higher-order systems beyond the solar vicinity. Star clusters yield controlled environments with known physical parameters, providing a way to explore homogeneous stellar samples. Combining modern optical and near-IR surveys, our main goal is to explore the region of the color-magnitude diagrams located above the sequence of equal-mass binaries, which is inhabited by unresolved triple and quadruple systems. Specifically, here we aim to discover a…

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astro-ph.GA

Tracing the Hidden Molecular Gas in the Small Magellanic Cloud with SOFIA and APEX

K. Rodriguez-Ambler, R. Herrera-Camus, M. Rúbio, A. D. Bolatto, D. Riquelme-Vásquez, K. Jameson, C. Muñoz-López, E. J. Tarantino et al.

In low-metallicity environments, reduced dust abundance weakens molecular cloud shielding against far-ultraviolet radiation, enhancing CO photodissociation and producing extended CO-faint or CO-dark molecular gas. The [CII] 158 $μ$m line is a key tracer of these CO-faint phases. We characterize the multiphase origin of [CII] emission and quantify the CO-faint molecular gas fraction across several regions of the Small Magellanic Cloud (SMC), the nearest low-metallicity ($\sim 0.2 Z_\odot$) galaxy…

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astro-ph.GA

Reigniting the FUSE I: Star Formation in Massive Elliptical Galaxies

Michael Reefe, Michael McDonald, Eric Miller, Thomas Brown

In this inaugural paper of our "Reigniting the FUSE" series, we present the data collection & reduction, methodology, and preliminary results for a comprehensive and homogeneous reanalysis of all 30 massive elliptical galaxies that have archival far-ultraviolet (FUV) spectra with the Far Ultraviolet Spectroscopic Explorer (FUSE). We perform SED fitting to these spectra, with aperture-matched photometry from GALEX, SDSS, DES/DECaLS, 2MASS, and WISE, and construct a catalogue of high quality const…

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gr-qcastro-ph.HEhep-th

Effective Field Theory of Gravity in Relativistic Media

Beka Modrekiladze

We develop an effective field theory of gravity in relativistic media. Integrating out the medium leaves vacuum gravity with updated Feynman rules: a graviton propagator dressed by the stress-energy two-point function of the environment, medium-induced bulk graviton vertices from higher correlators, and generalized worldline couplings encoded in matched Wilson coefficients. The diagram topologies are unchanged from vacuum, so different media (perfect fluids, collisionless matter, coherent scalar…

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astro-ph.SRastro-ph.GAastro-ph.IM

Calibration of the Next Generation Palomar Spectrograph as a Stellar Speedometer

Pranav Nagarajan, Kareem El-Badry

We calibrate the Next Generation Palomar Spectrograph (NGPS) for precision stellar radial-velocity (RV) measurements using repeated observations of 24 Gaia-ESO RV standards spanning $G=11$-$18$. Because NGPS is mounted at the Hale telescope's Cassegrain focus, changes in instrumental flexure produce wavelength-solution shifts of tens of km s$^{-1}$, with substantial time and wavelength dependence. We develop a pipeline that measures these shifts directly from each science exposure, using telluri…

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astro-ph.HEastro-ph.GA

Rapid radio variability in the $z\sim7$ blazar VLASS J0410$-$0139: Indication of a hidden population of weak radio jets at Cosmic Dawn

Silvia Belladitta, Eduardo Bañados, Anniek J. Gloudemans, Timothy W. Shimwell, Emmanuel Momjian, Huib Intema, Chiara Mazzucchelli, Christian Fendt et al.

Doppler boosting allows blazars to be detected out to high-$z$, making them promising probes of the intergalactic medium through the 21 cm forest. We report 0.144$-$11 GHz observations of the most distant known blazar, VLASS J041009.05$-$013919.88 at z$\sim$7, obtained with the upgraded Giant Metrewave Radio Telescope (uGMRT), the LOw Frequency ARray (LOFAR) and the Very Large Array (VLA). The first uGMRT epoch (300$-$820 MHz, April 2023) revealed an inverted radio spectrum which, combined with…

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astro-ph.GA

LOFAR radio properties of quasars hosting Extremely High Velocity Outflows

Amy L. Rankine, Paola Rodríguez Hidalgo

Quasar winds are a potential contributor to the radio emission observed in the so-called 'radio-quiet' quasars. Extremely High Velocity Outflows (EHVOs), with bulk velocities >0.1c, represent some of the most energetic of these winds. In this work, we investigate the radio properties of quasars hosting EHVOs in order to assess whether such high-velocity winds contribute to the observed radio emission. We cross-match the catalogue of EHVOs from the Sloan Digital Sky Survey with the high-sensitivi…

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astro-ph.SRastro-ph.EPastro-ph.GA

Deep H$α$ Imaging Survey of IC 348 with the Hubble Space Telescope: I. Accretion Properties of Stellar and Substellar Objects

Lillian Yushu Jiang, Brendan P. Bowler, Yifan Zhou, Adam L. Kraus, Sean M. Andrews, Lynne A. Hillenbrand, Michael J. Ireland, Zhaohuan Zhu et al.

Accretion governs the growth of young stars and the early evolution of their circumstellar disks, yet population-level measurements of accretion are often hampered by heterogeneous diagnostics and by samples preferentially selected toward disk-bearing or accreting objects. This can impact the mass accretion rate-stellar mass ($\dot{M}$-$M_\star$) relation, particularly at substellar masses. We present a uniform analysis of accretion in the $\sim$2 Myr-old star-forming cluster IC 348 based on dee…

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astro-ph.EPastro-ph.IM

Rotational broadening of exoplanet spectra in arbitrarily oriented systems: Application to reflected light

Sophia R. Vaughan, Laura Kreidberg

Exoplanet reflection spectra contain a wealth of information, which we are now beginning to access. At a high spectral resolution, the rotation of both the star and the planet affects the shape of the reflected spectral lines. This effect must be accounted for in high-resolution analyses and could be used to measure the orbital alignment of systems. In this work, we derive the rotational broadening kernels for arbitrarily aligned systems, both for the stellar spectrum viewed by the planet and fo…

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astro-ph.GAastro-ph.CO

Halo mass, star formation, and morphology in galaxies: A morphology-dependent connection between halo environment and star formation activity

G. Mountrichas, F. Shankar, F. J. Carrera, A. Georgakakis

Understanding the mechanisms responsible for quenching star formation in galaxies requires disentangling the roles of internal structure and large-scale environment. We investigate how galaxy morphology and specific star formation rate (sSFR) relate to the typical masses of host dark-matter halos (DMHs), and whether the halo--star formation connection depends on morphology. We analyse non-active galaxies in the VIPERS and Stripe 82 fields at $0.5 \leq z \leq 1.2$, combining DESI-based Sérsic cla…

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astro-ph.SRastro-ph.GAastro-ph.IM

Unresolved Binary Systems in the Rubin Era I: An Autoencoder Framework for Binary Identification Applied to 47 Tucanae

Tobias Géron, Alexander Laroche, Joshua S. Speagle, Maria R. Drout

Binary systems are extremely common and influence many areas of astrophysics, such as stellar evolution and cluster dynamics. In this work, we introduce flexAE, a framework that combines a classical autoencoder architecture with a dedicated classifier component. It is designed to distinguish between single stars and binary systems based on their broadband spectral energy distributions, using all available photometry simultaneously while accounting for observational uncertainties. We demonstrate…

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astro-ph.GA

A direct measurement of the tilting rate of the Milky Way disc

Guillaume F. Thomas, Benoit Famaey, Alicia Rivero, Giuseppina Battaglia, Rodrigo Ibata

The Milky Way disc is typically described, at lowest order, as a flattened rotating stellar component with a fixed spin axis. However, interactions and mergers with smaller galaxies are expected to have an impact on the disc properties. Such interactions can leave long-lasting signatures within galactic discs, including warps and corrugation waves that have already been detected in the Milky Way, but also a slow reorientation of the disc known as tilting, which has never been directly measured u…

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astro-ph.GA

Discovery of Very Minor Merger-Induced Star-forming Clumps at $z=3.33$ with JWST

Alexander de la Vega, Bahram Mobasher

High-redshift galaxies often contain ''clumps:'' compact, $\sim$kpc-scale regions of intense star formation. These substructures make up significant fractions of the masses and star-formation rates of their host galaxies and are expected to affect the morphologies of their hosts, such as by building up bulges. Studying clumps can therefore inform theoretical models of galaxy evolution. Two main mechanisms have been proposed for their formation: gas fragmentation from disk instabilities and compr…

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astro-ph.IMastro-ph.CO

Fast Lensing And Sub-minute High-accuracy photometry (FLASH) with JWST: Pipeline and Primordial Black Hole Microlensing Constraints from M31

David Rubin, Istvan Szapudi

Minute- and sub-minute microlensing provides a direct probe of compact dark matter at asteroid-mass scales, where primordial black holes with MPBH <~ 10^-10 Msol would produce short-duration, finite-source-suppressed amplifications of stars in extragalactic fields. To enable these measurements, we present FLASH: Fast Lensing And Sub-minute High-accuracy photometry with JWST, a pipeline designed to recover such events from JWST/NIRCam imaging by preserving detector-ramp time information and perfo…

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astro-ph.SRastro-ph.GAastro-ph.HE

The youngest white dwarf companion to a millisecond pulsar: Insights from NGC 362D

Greta Ettorre, Emanuele Dalessandro, Mario Cadelano, Alessandro Ridolfi, Cristina Pallanca, Paulo C. C. Freire, Vivek Venkatraman Krishnan, Maurizio Salaris et al.

We report on the identification of the optical counterpart to the recently discovered millisecond pulsar (MSP) NGC362D in the Galactic globular cluster NGC362 based on deep, multi-band, and multi-epoch Hubble Space Telescope observations. Our analysis robustly shows that this object is a very low-mass ($\sim0.18 M_{\odot}$) He white dwarf (WD) still in the pre-cooling phase. Interestingly, a detailed comparison with updated binary evolution models indicates that this object completed the mass-tr…

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astro-ph.SR

Evidence for Enhanced Helium Enrichment from Asteroseismology

Miqaela K. Weller, Marc H. Pinsonneault, Jennifer A. Johnson, Charles Shunyu Yao

The helium abundance of a star has a dramatic effect on luminosity, internal structure, and evolutionary timescales, yet direct helium measurements are unavailable for most stars. In this work, we infer stellar helium abundances by comparing observed and predicted luminosities for a sample of subgiants with asteroseismic masses from the APOKASC sample and spectroscopic parameters from recent survey compilations. Stellar luminosities are predicted using grids of theoretical stellar evolution mode…

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gr-qcastro-ph.IM

A compact time-frequency representation for gravitational-wave data analysis

Noah Pearson, Mesut Çalışkan, Sophie Bini, Neil J. Cornish

Time-frequency (wavelet) domain analyses are seeing greater use for gravitational-wave data analysis due to the advantages they have in handling non-stationary noise. A popular choice is the Wilson-Daubechies-Meyer (WDM) wavelet transform, which uses a window function that is very compact in frequency, but more spread out in time. In this work, we consider an alternative window function that is built from a sum of phase-shifted Gaussians. This "Gaussian" window is more symmetric in time-frequenc…

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astro-ph.GAhep-ph

Baryon-Accelerated Core Collapse in SIDM Halos and its Imprint on Galactic Disks

Zeineb Mezghanni, Elliot Y. Davies, Adriana Dropulic, Gonzalo Herrera, Abdelaziz Hussein, Lina Necib

The gravitational coupling between dark matter (DM) halos and the baryonic structures they host is one of the most powerful windows into the particle nature of DM. Self-interacting dark matter (SIDM) presents a minimal, well-motivated extension to the dark sector with dramatic consequences for the structure of galaxies and their halos. However, the impact of baryons on SIDM halo evolution and the resulting galactic structure has been underexplored in Milky Way (MW)-size galaxies. In this paper,…

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astro-ph.IM

The information content of optical intensity interferometry

Neal Dalal, Biwei Dai, Matthew K. Browning

Optical intensity interferometry (II) can in principle resolve structure on angular scales $θ\sim λ/B$, but it measures only the squared visibility $|{\cal V}|^2$, discarding Fourier phase. We quantify what information can actually be recovered from phase-less $|{\cal V}|^2$ measurements as a function of the aggregate signal-to-noise ratio and array configuration, using score-based diffusion models as non-parametric image priors. We construct an image reconstruction pipeline, and validate it by…

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astro-ph.EPastro-ph.IMastro-ph.SR

POSTELLAR: Posterior Stellar Spectrum Sampling - An Alternative to Approximate Stellar Spectra for Exoplanetary Analysis

Dhvani Doshi, Nicolas B. Cowan, Yashar Hezaveh, Gabriel Missael Barco, Étienne Artigau

We present a novel approach to perform posterior sampling of the underlying stellar spectrum in high-resolution spectroscopic observations. Our method, postellar, coherently combines information from empirical observations and physics-based models, enabling more accurate spectral recovery while providing uncertainties that can be propagated into downstream analyses. This is accomplished by treating the intrinsic stellar spectrum as a latent variable and performing posterior sampling under a Gaus…

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astro-ph.COastro-ph.GA

Exploring the dark sector through galaxy dynamics in clusters

Andrea Biviano, Lorenzo Pizzuti, Antonaldo Diaferio

Galaxy clusters are among the most powerful laboratories to probe fundamental physics, from the formation of cosmic structures to the nature of dark matter, dark energy, and gravity. Realizing their full potential requires accurate and unbiased determinations of their mass profiles, a longstanding challenge in cluster cosmology. In this context, the kinematics of member galaxies in clusters has become a key tool to reconstruct the mass distribution and to investigate the dynamical properties of…

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astro-ph.EP

Two extremely irradiated volatile-rich sub-Neptunes with companions in the TOI-426 and TOI-1839 systems: Insights into arrival and survival near the lower edge of the Neptunian desert

A. Castro-González, O. Barragán, D. J. Armstrong, A. Aguichine, V. Bourrier, D. Ehrenreich, E. X. Tao, J. Lillo-Box et al.

Using TESS photometry and 147 HARPS radial velocities, we confirm two extremely irradiated, volatile-rich sub-Neptunes near the lower edge of the Neptunian desert: TOI-426 b and TOI-1839 b, orbiting the solar-type stars HD 34390 and TYC 304-865-1. We modelled stellar activity with shared-timescale and multidimensional Gaussian processes. The planets have orbital periods of approximately 1.32 and 1.42 days, radii of $2.19\pm0.09$ and $2.27\pm0.10$ Earth radii, and masses of $6.7\pm1.8$ and $7.10\…

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astro-ph.COastro-ph.IM

Tracing the Cosmic Origins: Machine Learning Reconstruction of the Primordial Density Field from EoR Observations

Anchal Saxena, P. Daniel Meerburg, Guochao Sun, Tzu-Ching Chang, Lluís Mas-Ribas

Reconstructing the initial conditions of the Universe from late-time tracers would unlock cosmological information buried by non-linear structure formation and astrophysics. We reconstruct the initial density field at $z\sim300$ from simulated 21-cm and CO(1-0) line-intensity maps at $z\sim8$ generated with LIMFAST. Using a three-dimensional U-Net, we reconstruct the initial conditions and evaluate its impact on cosmological parameter constraints. The two tracers probe complementary environments…

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astro-ph.SRastro-ph.GA

Metallicity dependence of Wolf-Rayet binaries using detailed binary models: An absence of long-period systems at low metallicity

Max M. Briel, Eirini Kasdagli, Tassos Fragos, Tomer Shenar, Jeff J. Andrews, Denzel Goh, Abhishek Chattaraj, Seth Gossage et al.

Observations of Wolf-Rayet (WR) stars in binaries in the SMC and LMC suggest a preference for short period ($P\lesssim30$ days) orbits, with an apparent absence of WRs in long-period systems. The Galactic population does extend to longer periods but shows a deficit in long-period WR binaries compared to their progenitors, the O-star population. Across these populations a nearly constant binary fraction has been observed. We aim to characterize the population of WR binaries across a range of meta…

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astro-ph.EPastro-ph.GA

Ion abundances in the plasma tail of 3I/ATLAS show that it is N2-rich

Lea Ferellec, Cyrielle Opitom, Colin Snodgrass

Interstellar objects allow us to compare the early planetary formation process in the Solar System and around other stars. The second and third interstellar objects, 2I/Borisov and 3I/ATLAS, showed visible signs of activity, making it possible to assess their composition via spectroscopic analysis of their gas coma. While neutral volatiles surrounding comets are easily probed by common spectrographs, ion emissions emanate mostly from the tail, making them easier to detect with integral-field uni…

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gr-qcastro-ph.COastro-ph.IM

Fast Bayesian Inference for Long-Duration Gravitational-Wave Signals in 3G detectors

Anand S. Sengupta

Third-generation (3G) gravitational-wave detectors will observe binary-neutron-star inspirals for nearly a day, so Earth's rotation becomes part of the signal rather than a negligible correction. This destroys the usual separation between intrinsic and extrinsic parameters and creates a major computational bottleneck for Bayesian inference. We show that the exact five-harmonic Jaranowski-Krolak-Schutz (JKS) decomposition restores the separation of the rotating antenna amplitude response from the…

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gr-qcastro-ph.COastro-ph.IM

Fast Bayesian Inference for Long-Duration Gravitational-Wave Signals in 3G detectors

Anand S. Sengupta

Third-generation (3G) gravitational-wave detectors will observe binary-neutron-star inspirals for nearly a day, so Earth's rotation becomes part of the signal rather than a negligible correction. This destroys the usual separation between intrinsic and extrinsic parameters and creates a major computational bottleneck for Bayesian inference. We show that the exact five-harmonic Jaranowski-Krolak-Schutz (JKS) decomposition restores the separation of the rotating antenna amplitude response from the…

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astro-ph.EP

Dust Substructures and Line Perturbations driven by a Forming Planet in J16120

Anibal Sierra, Andrés F. Izquierdo, Paola Pinilla, Kan Chen, Myriam Benisty, Laura Pérez, Teresa Paneque-Carreño, Carolina Agurto-Gangas et al.

Hints of planet formation have been independently reported within the gap of the disc around 2MASS J16120668-301027 from millimetre continuum, infrared, and H-alpha observations. In this work, we present new evidence for ongoing planet formation based on Atacama Large Millimeter/submillimeter Array (ALMA) Band 7 observations, detecting 0.87 mm dust continuum emission together with 12CO (J=3-2) and 13CO (J=3-2) line emission. Visibility modelling of the continuum data reveals an inner disc and tw…

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astro-ph.HEgr-qc

Electromagnetic alignment and jet precession around supermassive black holes: Quasi-periodic oscillations in tidal disruption events

Pau Amaro-Seoane, Leif Lui, Alejandro Torres-Orjuela, Xian Chen

We evaluate quasi-periodic oscillations and jet formation in tidal disruption events using the covariant formulation of electromagnetic angular-momentum transfer. General-relativistic frame-dragging tears apart misaligned transient accretion flows, forming an isolated inner mini-disk. The accumulation of magnetic flux on the event horizon powers a relativistic jet via the Blandford-Znajek mechanism. Because the magnetic field anchors to the precessing mini-disk, the jet axis rotates, generating…

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astro-ph.EP

Contrasting C/O ratios in Uranus and Neptune from disequilibrium chemistry: A clue to distinct evolutionary pathways?

T. Briand, V. Hue, O. Mousis, T. Cavalié, T. Benest Couzinou, A. Schneeberger, M. D. Hofstadter

The formation of Uranus and Neptune remains poorly constrained largely due to uncertain deep elemental abundances. Carbon monoxide (CO), a disequilibrium species in the upper troposphere, provides an indirect constraint on the deep oxygen abundance. We investigate the deep O/H and C/O ratios of the ice giants and their formation history by accounting for meridional variations in atmospheric structure and uncertainties in chemical kinetics. We extended a 1D thermochemical and diffusion model into…

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