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Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.EP

Closing the Gap: A Test of the Streaming Instability Using Simulations and Observations of the Cold-Classical Kuiper Belt Size Distribution

Weston Hall, Jacob B. Simon, Jeonghoon Lim, Daniel Carrera, Matthew Small

How planetesimals form is a major open question in studies of planet formation, as the growth of smaller solids must overcome barriers such as radial drift, fragmentation, and bouncing. The leading model is that planetesimals form by the gravitational collapse of dense particle clumps that have been aerodynamically collected via a process known as the streaming instability (SI). While the SI has passed several observational tests, a critical test remains: a successful comparison with the size di…

astro-ph.IM

An Assessment of the Triangulation Capabilities of a Multi-Site All-Sky Infrared Camera Array

Abraham Loeb, Alex Delacroix, Ezra Kelderman, Eric Masson, Regina Sarmiento

The Galileo Project operates three autonomous multi-camera observing sites near Las Vegas, Nevada, separated by baselines of $2$ and $10\,$km, with the goal of characterizing the populations of natural and human-made objects that cross the sky and thereby isolating any event that fits none of them. Each site carries an array of eight long-wave infrared (LWIR) cameras arranged in a fixed dome-like structure, an IR-Dalek, providing $360^{\circ}$ azimuthal coverage. We report the commissioning of t…

astro-ph.EPastro-ph.IMcs.AI

AEGIS: Differentiable Mars Climate Model with Neural Closures

Sameera S Kashyap, Victor Cruz, Angel Yepez, Razvan Marinescu

General circulation models (GCMs) are the primary tool for simulating planetary atmospheres. They play a vital role in understanding Mars's atmosphere, as forecasting its unique weather is mission-critical for operations such as entry, descent, and landing. Mars poses unusual challenges for these models, as observations are sparse compared to Earth. In addition, a thin \co{} atmosphere alongside a radiatively active dust cycle creates a volatile atmosphere with large diurnal temperature swings a…

astro-ph.HE

Observed x-ray spectral indices support magnetic buoyancy sourced coronae in Seyfert active galactic nuclei

Ketevan Kotorashvili, Eric G. Blackman

Standard radiation spectra modeling of active galactic nuclei like Seyfert galaxies typically involves tuning the relative contributions from an optically thick disc, optically thin corona, dust torus, and outflow by hand to match observations. The physics that quantifies this relative partitioning is not precisely understood. Here we make progress toward improving this understanding by testing the implications of a conceptual paradigm that the corona is supplied from below only by magnetic fiel…

astro-ph.EPastro-ph.GAastro-ph.IM

Measuring the Age and Initial Composition of Interstellar Objects

Aster G. Barry-Taylor

Measuring the age and composition of interstellar objects is necessary to understand their origins. However, existing methods for measuring the age are either imprecise or require an unusually bright target, while the composition is confounded by the effects of Galactic cosmic rays, which drive chemical reactions in the cometary matrix. As the Vera C. Rubin Observatory expands the census of interstellar objects, measuring these properties will be critical to understanding the overall population.…

astro-ph.COastro-ph.GAastro-ph.SRgr-qchep-ph

Stars Would Remember a Recent Gravitational Transition: Testing G-step Resolutions of the Hubble Tension with Red Dwarfs

Jeremy Sakstein, Harry Desmond

We test the hypothesis that Newton's gravitational constant underwent a rapid transition approximately $73$-$130\,{\rm Myr}$ ago, as proposed in some resolutions of the Hubble tension. Fully convective red dwarf stars with masses below $\sim0.35\,M_\odot$ have thermal timescales comparable to the proposed transition look-back times, so an appreciable present-day memory can remain. We show that a rapid step in $G$ induces measurable changes in their radii and confront these predictions with mass-…

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

A concordance model of neutron star kicks

Cheyanne Shariat, Kareem El-Badry, Smadar Naoz

Neutron stars (NSs) receive natal kicks during supernovae that affect their survival in binaries and motion through the Galaxy. The global distribution of these kick velocities across the NS population remains uncertain. Here, we combine the orbital properties and birth rates of Gaia NS and Be+NS binaries with velocity constraints from young isolated pulsars to construct a concordance model of NS natal kicks. We find that all three populations can be jointly described by a shared bimodal kick di…

astro-ph.HEastro-ph.SR

A Unified Multi-Band Secular Framework for the Hierarchical Triple PSR J0435+3233 System

Achamveedu Gopakumar, Vidit Singh, Abhimanyu Susobhanan, Mauri J. Valtonen, Sayantan Bhattacharya, Di Li, Hong-Liang Yan, Jianping Yuan et al.

The millisecond pulsar PSR J0435+3233, discovered by FAST, exhibits an unusually large apparent spin-down rate, potentially reflecting line-of-sight acceleration from a distant companion. Recent investigations reveal a hierarchical triple consisting of an inner pulsar-helium white dwarf binary with an orbital period of ~8 days, orbited by a G-type subgiant tertiary on an eccentric ~74 yr orbit. The current timing description admits two distinct geometrical solutions. We develop a singly averaged…

astro-ph.GA

The Merian Survey: A Statistical Census of Bright Satellites of Sub-Milky Way-Mass Galaxies

Lucas S. Mandacarú Guerra, Jiaxuan Li, Yue Pan, Jenny E. Greene, Shany Danieli, Joy Bhattacharyya, Alyson M. Brooks, Song Huang et al.

Satellite populations provide sensitive tests of the galaxy-halo connection, but studies have largely focused on Milky Way (MW)-mass host galaxies or a small number of nearby dwarf galaxy hosts. Here we present a statistical census of bright, star-forming satellite galaxies around sub-MW-mass hosts using the first data release of the Merian Survey. Our sample consists of 357 hosts with stellar mass $10^{9.5} 3$. Satellite abundance increases with host stellar mass across the sub-MW regime, exten…

astro-ph.EP

The Nearest, Brightest Debris Disk Host Stars: Updated Photosphere Models and Dust Properties for Stars with Saturated 2MASS Photometry

Inbok Yea, Sarah Dodson-Robinson, Cesar Julian Bustos Sanchez, John E. Gizis

To discover and characterize debris disks, one must obtain high-quality photometry in order to accurately fit photosphere models for the host stars. Since the $K$ band always falls on the Rayleigh-Jeans side of a star's spectral energy distribution (SED), its reliability is particularly important for uncovering mid-infrared excess emission from dust. While Two Micron All Sky Survey (2MASS) photometry is the near-infrared benchmark for most stars that host debris disks discovered by Spitzer and t…

astro-ph.COastro-ph.GA

Baryonic Imprints on DM Halos: characterizing the full concentration-mass probability distribution with CAMELS

Elisa J. Gao, Dhayaa Anbajagane

The halo concentration, which represents the distribution of matter within a halo, is a vital tool for modeling the matter distribution on scales ranging from megaparsecs to sub-kiloparsecs. While significant progress has been made on connecting the impact of astrophysics on the mean concentration as a function of halo mass, the same connection to higher moments of the concentration distribution remains far less explored. We employ the IllustrisTNG runs in the CAMELS simulation suite to simultan…

astro-ph.HE

Polarimetry of Black Hole Spin and Axisymmetric Emission Geometry

Vadim Bernshteyn, Daniel C. M. Palumbo, Dominic Chang, Tintin Nguyen

The Event Horizon Telescope array has measured the average polarimetric spiral morphology of black hole accretion disks using the so-called ``$β_2$'' coefficient. This measurement is dominated by the weakly lensed, direct ($n=0$, counting photon half-orbits) image of the disk, providing insight into magnetic field structure around the M87* black hole. The future space-based Black Hole Explorer mission is expected to extend these capabilities, allowing for $β_2$ measurement of the strongly lensed…

astro-ph.HE

Classification of X-ray Binaries in NGC 6946 with the use of Multiwavelength Data

Senay Avdan, Hasan Avdan, Eda Sonbas, Kalvir S. Dhuga

We identified X-ray binary (XRB) candidates in the galaxy NGC 6946 using archival {\it Chandra} data. A total of 98 XRB candidates were detected within the 0.3$-$8 keV energy range, with luminosities between 10$^{36}$ and 10$^{40}$ erg~s$^{-1}$. X-ray color-color diagrams were constructed for these sources, classifying 57 as high-mass X-ray binaries (HMXBs) and 8 as low-mass X-ray binaries (LMXBs). The X-ray temporal variability of the sources was analyzed, revealing that 40 sources exhibit vari…

astro-ph.GA

The differences in the Narrow Line Region of nearby QSOs 1 and QSOs 2: II - Signatures of kinetic feedback

Gabriel R. Hauschild-Roier, Thaisa Storchi-Bergmann, Rogério Riffel, Vincenzo Mainieri, Lara Gatto

We compare the integrated kinematic properties of the Narrow-Line Region (NLR) of ~1500 type 1 and ~700 type 2 QSOs at 0.4 < z < 0.5 using emission-line profiles from SDSS-IV spectra. The NLR [OIII] 5007 and Hbeta emission lines are fitted using a two-component model comprising a narrow (v_n, sigma_n) and a broad component (v_b, sigma_b), while fainter lines are fitted with a single Gaussian component. Both QSO types exhibit similar median narrow-component velocities (v_n ~ 0) and velocity dispe…

astro-ph.HEastro-ph.GAgr-qcmath-ph

Relaxation of a Vlasov gas to an inhomogeneous state due to phase space mixing in an axisymmetric potential: A Newtonian analogy of the Kerr orbital motion

Ana Laura Garc\a'ia-Perciante, Merce Guerrero, Daraío Naúañez, Olivier Sarbach

We explore the dynamics of a Vlasov gas propagating in an external axisymmetric potential consisting of a central potential with an additional quadrupolar component which gives rise to two potential wells along the symmetry axis. Employing independently $N$-particle simulations and statistical methods, we show that an initially homogeneous and isotropic configuration evolves to an inhomogeneous final state with overdensities located at the wells. The quadrupolar component is chosen such that the…

astro-ph.HE

Blasts from the Past: UHECR Excesses from a Population of GRB 21009A-like Transients

Nestor Mirabal

The most prominent feature in the ultra-high-energy cosmic ray (UHECR) sky is a significant excess of events from the vicinity of Centaurus A (Cen A). In this paper we investigate whether the excess may be caused by a past GRB 221009A-like event rather than Cen A itself. If an extraordinary gamma-ray burst (GRB) went off in one of the dwarf galaxies within the Cen A/M83 group, intergalactic magnetic deflections would naturally spread out and delay its cosmic ray signal, making it visible for $\s…

astro-ph.IM

The Nancy Grace Roman Space Telescope Wide Field Instrument: Characterization of the Brighter-Fatter Effect in a Roman H4RG-10 Detector using the Talbot Effect

Jennie Paine, Ami Choi, Christopher Merchant, Timothy D. Brandt, Jeffrey Kruk, Joshua E. Schlieder, Edward J. Wollack, Analia Cillis et al.

The Nancy Grace Roman Space Telescope will conduct several community-driven surveys using its Wide Field Instrument (WFI), which contains 18 Teledyne H4RG-10 near-infrared detectors in the focal plane. Roman's wide area survey to measure weak gravitational lensing places particularly stringent requirements on point spread function (PSF) precision for the WFI. The brighter-fatter effect (BFE) is a nonlinear detector effect caused by the deflection of new charge away from pixels with previously ac…

astro-ph.HEastro-ph.COastro-ph.GA

The Virgo Cluster as a Case Study for Ancient Cosmic Ray Halos in Radio and X-rays

Philip F. Hopkins, Emily M. Silich, Jack Sayers, Sam B. Ponnada, Isabel S. Sands

Virgo is the nearest cool core (CC) galaxy cluster, and is archetypal of the class of X-ray weak CCs. Despite the X-ray continuum implying a large cooling rate ($\gtrsim 10\,{\rm M_{\odot}\,yr^{-1}}$), measurements of cooler gas phases, dust, and star formation show almost no cooling outside the M87 nucleus. It is also known that M87$^{\ast}$ is a prodigious source of cosmic ray (CR) leptons observed in radio and $γ$-rays, and recent radio observations have shown that the M87 radio halo is low-f…

astro-ph.GA

Internal Radiative Feedback Triggers Global Collapse and Direct-Collapse Black Hole Formation in Metal-free Atomic-Cooling Haloes

Masaki Kiyuna, Sunmyon Chon, Kazuyuki Omukai, Raffaella Schneider

The formation of heavy seed black holes from the collapse of supermassive stars (SMSs) is a promising pathway to the supermassive black holes (SMBHs). In the conventional direct-collapse scenario, however, SMS formation requires an extremely strong external far-ultraviolet (FUV) field to suppress H$_2$ cooling and fragmentation. Here, we use cosmological radiation-hydrodynamic simulations to show that SMSs can form in metal-free atomic-cooling haloes even under subcritical FUV backgrounds with $…

astro-ph.SR

Spectroscopic monitoring of long secondary period variables. The case of J-type carbon stars

L. Planquart, A. Jorissen, H. Van Winckel

Long-secondary-period (LSP) variables are a subclass of long-period variables whose origin is a matter of debate. J-type carbon stars are a subclass of carbon stars enriched in 13C, and the origin of this chemical peculiarity is unclear. In this paper, we report on the discovery of a LSP in two J-type carbon stars: VZ Per and UV Cam. Methods. A decade-long spectroscopic monitoring was used to obtain a long-term radial-velocity curve for the two stars. From a frequency analysis, we isolated a LSP…

astro-ph.GA

SCALES. II. The Internal Composition of Giant Star-Forming Clumps at $z = 1 - 4$

Boris S. Kalita, Adélaïde Claeyssens, Luis C. Ho, Miroslava Dessauges-Zavadsky, Natascha M. Förster Schreiber, Emanuele Daddi, John D. Silverman, Naval Kishor Bhadari et al.

Star-forming structures of scale $\sim0.5-1\,\mathrm{kpc}$, dubbed 'giant' star-forming clumps, are routinely detected in unlensed surveys of $z > 1$ galaxies. Two scenarios are usually invoked to explain their existence -- genuine physical structures or resolution-driven artifacts -- yet distinguishing between them requires characterizing their internal structure. In this work, part of the Star-Forming Clumps As Layered Emergent Structures (SCALES) series, we hence ask: What is inside a giant c…

astro-ph.GA

SCALES. I. Bridging Lensed Clump - Giant Clump Scales in Lensed Galaxies at $z=1-4$

Boris S. Kalita, Adélaïde Claeyssens, Luis C. Ho, Miroslava Dessauges-Zavadsky, Natascha M. Förster Schreiber, Emanuele Daddi, John D. Silverman, Naval Kishor Bhadari et al.

Dense star-forming regions in $z>1$ galaxies, often termed 'clumps', have been studied across two distinct regimes of telescope resolution, each motivating interpretations in tension with the other. In the SCALES series (Star-Forming Clumps As Layered Emergent Structures), we aim to connect star-forming structures across scales, from the $\sim100\,\mathrm{pc}$ clumps in lensed studies to the $\sim\mathrm{kpc}$-scale ''giant'' clumps in unlensed surveys. In this first paper, we present a differen…

astro-ph.EP

Temporal Variability of Titan's Middle-Atmospheric Zonal Winds from Southern Fall to Late Winter (2016-2023)

Martin A. Cordiner, Yuan Lian, Juan M. Lora, Nicholas A. Lombardo, Lucy Wright, Jonathon Nosowitz, Richard Cosentino, Nicholas A. Teanby et al.

Previous ALMA observations have revealed unexpectedly strong and rapid variations in Titan's high-altitude equatorial zonal winds, which present a challenge to our understanding of this moon's atmospheric dynamics. Here we report further measurements of Titan's zonal wind field at middle atmospheric altitudes $\approx200$-490 km, based on ALMA observations of spatially and spectrally resolved CH$_3$CN emission between 2016-2023 (corresponding to a solar longitude $L_s=81.6^{\circ}$-$156.4^{\circ…

astro-ph.IM

Tracing the evolution of galaxy environments with manifold learning

Ana Sofía M. Uzsoy, Claire Lamman, Peixin Zhu, Melanie Weber

We present SONDE (SOrted Neighbor Distance Embedding): a scalable manifold learning approach to create a nuanced, continuous, low-dimensional representation of the geometry of galaxies' local environments. SONDE is a variation on Isomap that uses similarity distances between galaxy neighborhoods to create an embedding space, within which galaxies cluster according to their neighborhood geometries. We additionally present a novel method to project different datasets into the same embedding space,…

astro-ph.GA

Searching for Green Pea Galaxies in the SFACT Survey

Kristin N. Baker, John J. Salzer, Brooke Kimsey-Miller, Samantha W. Brunker, David J. Carr, Jennifer Sieben, Steven Janowiecki, Samir Salim et al.

Green Pea galaxies (GPs) are a class of rare, extreme star-forming galaxies whose physical properties closely resemble high-redshift Ly-α emitting galaxies. Their high equivalent width [O III] emission lines make them readily identifiable in surveys of emission-line galaxies like the on-going deep, narrowband Star Formation Across Cosmic Times (SFACT) survey. In this study, we use broadband gri colors and [O III] equivalent widths derived from narrowband images to select a new sample of ~120 GP…

astro-ph.COastro-ph.GA

Baryonic Imprints on DM Halos: the concentration-mass relation and its dependence on 28 model parameters in the CAMELS suite

Cami Delgado, Dhayaa Anbajagane

The evolution of baryons in halos, as well as their gravitational impact on the total-matter phase space, has a rich phenomenology and is vital in answering many questions in both cosmology and astrophysics. We use the CAMELS simulation suite to quantify the impact of twenty-three different galaxy formation parameters/processes (as well as five cosmological parameters) on the concentration--mass relation, $c_{\rm vir}$ - $M_{\rm vir}$, which characterizes the radial density distribution in halos…

astro-ph.IMphysics.optics

Design, Fabrication, and Free-Space Characterization of a Two-Photon-Polymerized Nano-printed Photonic Lantern

Kyra Watts, Natasha Popenoe, Benjamin Gerard, Paul Pax, Dominic Sanchez, David Feng, C. Cole Dunn, Cari Johnston et al.

Photonic lanterns provide an interface between multimode optical fields and arrays of single-mode waveguides, making them promising components for modal filtering, wavefront sensing, and high-contrast astronomical instrumentation. We present the design, simulation, two-photon-polymerization fabrication, and free-space characterization of a compact photonic lantern optimized for operation at $ 1050~\mathrm{nm} $. The device was designed to transform a multimode input into five nominally single-mo…

astro-ph.COastro-ph.IM

Map-based asymmetric beam treatment: application of real-space beam patterns in CMB data analysis

Artem Basyrov

Real telescope beams are asymmetric, breaking the simple $B_{\ell}$ factorisation in harmonic space and coupling modes across $\ell$ and $m$. We develop a map-domain treatment in which beam convolution is a local, scan-dependent operation applied directly to the time-ordered data (TOD), accommodating the full beam shape and giving a direct handle on intensity-to-polarisation ($I \rightarrow P$) leakage. A noiseless validation against spherical-harmonic convolution reproduces the input temperatur…

astro-ph.COastro-ph.IM

A novel, fast, and accurate code for cosmological loop calculations

Tjark Harder, Luca Amendola, Thiago S. Pereira, Miguel Quartin

We introduce neckar, a public code for the one-loop matter and galaxy power spectrum, as well as correlation function, in the Eulerian Effective Field Theory of Large-Scale Structure (EFTofLSS). It is based on the FFTLog expansion, and is designed for fast and accurate parameter inference from large-scale structure data, making it a powerful tool for high-dimensional Bayesian analyses of current and upcoming galaxy surveys. neckar combines several numerical and analytical improvements, including…

astro-ph.HEgr-qc

Forward Bayesian Inference for the Binary Black Hole Populations

Poulami Dutta Roy, Tanmaya Mishra, Achal Kumar, Sergey Klimenko

We present PopCWB, a Bayesian framework for the inference of the binary black hole (BBH) population based on the unmodeled search pipeline coherent WaveBurst (cWB). The standard population analysis takes an inverse approach by inferring the underlying population model parameters for a given set of detected events using the individual posterior samples. In PopCWB, we take a forward approach to population inference by varying population models to identify the most optimal one which describes the o…