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Research Trends

Latest preprints in space engineering and astrophysics.

physics.space-ph

Unraveling the Generation Mechanism of a Mid-Latitude Plasma Blob and the Evidence of Its Rare Interaction with a MSTID Phase Front

D. Patgiri, R. Rathi, V. Yadav, D. Chakrabarty, M. V. Sunil Krishna, S. Kannaujiya, S. Sunda, Y. Otsuka et al.

We report observations of two distinct nighttime F-region irregularities, plasma blob (localized density enhancement) and medium-scale traveling ionospheric disturbance (MSTID), in O(1D) 630.0 nm all-sky airglow images from Hanle (32.7°N, 78.9°E; Mlat~24.1°N), Ladakh, India, during the geomagnetically quiet (Ap=6) night of 06 July 2021. Global vertical total electron content (VTEC) maps revealed that the plasma blob developed beyond the southern edge of imager's field-of-view before appearing in…

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astro-ph.HEhep-ph

Machine Learning Detection of Non-Axisymmetric Fast Flavor Instabilities in Compact Objects

Madhurima Chakraborty, Sajad Abbar, Meng-Ru Wu, Francois Foucart, Zewei Xiong

Neutrinos in dense astrophysical environments such as core-collapse supernovae (CCSNe) and neutron star mergers (NSMs) can undergo FFCs, which could develop on extremely small scales. A necessary condition for the occurrence of FFCs is the presence of a zero crossing in the electron lepton number (ELN) angular distribution of neutrinos. In this work, we explore machine learning (ML) approaches to detect non-axisymmetric ELN crossings in these environments, based on input features of the $ν_e$ an…

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astro-ph.HEastro-ph.SR

Photometric and Spectroscopic Studies of Type Ic Supernovae SN 2020akf and SN 2021mxx

Mulchand Kurre, K. R. Sahu, Shrutika Tiwari, Yogita Patel, N. K. Chakradhari, D. K. Sahu, Rishabh Singh Teja, G. C. Anupama et al.

We present a comprehensive analysis of optical photometry and medium-resolution spectroscopy for Type Ic supernovae (SNe) SN 2020akf and SN 2021mxx. Our study covers the evolution of SN 2020akf from -5 to 109 days and SN 2021mxx from -3 to 115 days relative to their B-band maximum. Their peak quasi-bolometric luminosities are estimated at logL_bol = 42.37 +- 0.02 and 42.21 +- 0.02 erg/s, respectively. The velocities of the ejecta, derived from the Fe II 5169 A line at maximum light, are approxim…

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astro-ph.IM

Estimation of the laser guide star uplink tip-tilt using aperture size diversity

Pierre Jouve, Thierry Fusco, Carlos M. Correia, Cédric Taissir Heritier, Jean-François Sauvage, Benoit Neichel

Laser guide star (LGS) adaptive optics cannot directly measure tip-tilt (TT), forcing reliance on natural guide stars and limiting sky coverage. We propose estimating the uplink TT from telemetry acquired at the laser launch telescope alone, operated in a monostatic configuration as both emitter and receiver. Extracting TT over concentric disks of different diameters within the receiving pupil yields signals mixing uplink and downlink contributions in different proportions; this aperture size di…

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astro-ph.EPphysics.geo-ph

Discrimination of Tectonic, Swarm and Impact-related Marsquakes using Spectral Characteristics

Simon C. Stähler, Savas Ceylan, Nikolaj Dahmen, John Clinton, Domenico Giardini

The NASA InSight mission observed over 2000 marsquakes in the course of its three year mission. These quakes varied in magnitude between 1.5 and 4.5, as well as in spectral content. We present a simple framework to describe the spectral characteristics of all observed marsquakes, based on source process; propagation through the mantle or crust; and local, receiver-side amplification. We assign to each quake an objective measure of its amplitude, as well as the spectral decay created by the durat…

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astro-ph.IM

Scaling laws for multi-object spectrographs: empirical relationships and the photonic advantage of CAWSMOS

Kalaga V. Madhav, Martin M. Roth

Conventional multi-object spectrographs (MOS) incur masses and costs that scale unfavourably with channel count~$N_\mathrm{ch}$ and resolving power~$\mathcal{R}$. A dataset of eight fibre-fed MOS-VIS instruments (1995--2024) is compiled and analysed. Ordinary least-squares fitting yields a mass function $M \propto N_\mathrm{ch}^{0.78\pm0.28}$; the resolving-power exponent is empirically consistent with zero ($γ= 0.20\pm0.37$) but is predicted analytically to lie in $\mathcal{R}^{0.8\text{--}2.0}…

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

A Fast Concentric-disk Contour Integration Method For Microlensing Limb-darkening Effect

Suwei Wang

Incorporating limb darkening is a computationally demanding step in contour-integration-based microlensing modeling. Conventional concentric-ring integration is incompatible with high-order quadrature schemes, limiting efficiency. We develop a new concentric-disk method, which reformulates the limb-darkening integral and enables the application of high-order adaptive quadrature, significantly accelerating the computation. While mainly demonstrated using a linear limb-darkening profile, the metho…

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astro-ph.GAastro-ph.HE

Accretion-disk formation around orbiting stellar black holes in gaseous star clusters

Zacharias Roupas

We consider low-mass black holes (BHs) moving in regular orbits in the cores of non-rotating gaseous star clusters, representative of proto-stellar clusters or the centers of protogalaxies. We argue that as the BH's sphere of influence -- the Bondi sphere -- is advected along the BH trajectory, the transverse velocity shear between the inner and outer hemispheres injects angular momentum, driving the formation of an accretion disk. Coriolis forces oppose angular momentum injection, delaying disk…

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astro-ph.GA

Bridging the mass gap: Diffuse radio emission in GAMA galaxy groups using EMU and DINGO survey data

Sai Wagh, Tessa Vernstrom, Luke J. M. Davies, Lister Staveley-Smith, Stefan Duchesne, Christopher J. Riseley, Timothy J. Galvin, Franco Vazza et al.

Diffuse radio emission provides a powerful probe of non-thermal processes in the large-scale structure, yet its properties in galaxy groups remain poorly constrained. Using deep 943 MHz radio continuum data from the Evolutionary Map of the Universe (EMU) and 1.37 GHz data from the Deep Investigations of Neutral Gas Origins (DINGO) survey, we investigate diffuse radio emission in 400 galaxy groups selected from the GAMA survey at $z < 0.1$. We employ a multi-resolution filtering technique to supp…

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astro-ph.HEastro-ph.GA

Astrophysical Population Coordinates for Supermassive Black Hole Binaries in Pulsar Timing Array Inference

Yikun Li, Muhammad Ahmad, Shaoguang Guo, Lang Cui

Pulsar timing arrays can probe the population physics of supermassive black-hole binaries through the nanohertz gravitational-wave background. We construct a phenomenological forward model that follows source abundance, binary residence time, the high-mass population, finite-source strain moments, and the pulsar timing response. The simulated observables constrain three standardized population coordinates: $β$, which controls the residence-time and spectral response; $φ_{eff}$, which describes s…

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astro-ph.IM

The Lightspeed project: high-speed, ultra-low read noise imaging and polarimetry for the Magellan telescopes

Christopher Layden, Kevin Burdge, John J. Piotrowski, Gabor Furesz, Juliana Garcia-Mejia, Jack Dinsmore, Roger W. Romani, David Osip et al.

Lightspeed will be an ultra-fast (> kHz), ultra-low read noise, multicolor (ugriz + IR) imager for the 6.5 meter Magellan Clay telescope. In a single-channel configuration, Lightspeed will also enable single-shot linear polarimetry, narrowband imaging, or white-light imaging. Lightspeed is designed around groundbreaking single-photon-resolving detector technologies: deep sub-electron read noise CMOS image sensors from Fairchild Imaging and a HgCdTe avalanche photodiode array from Leonardo. Here…

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astro-ph.IMastro-ph.GAastro-ph.SRphysics.data-an

Demystifying image-recovery from radio interferometers: toward a multiscale predictive model

Dan Miao, Guang-Xing Li

Radio interferometers suffer from the missing short-spacing problem, losing large-scale diffuse emission. This missing flux underestimates gas mass and biases key metrics like star formation efficiency. Quantifying this scale-dependent loss currently relies on computationally intensive mock observations, lacking an analytical image-domain framework. We introduce the Constrained Diffusion Decomposition (CDD) method to decompose an input image ($I_{\mathrm{in}}$) into $n$ continuous scale-space co…

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astro-ph.GA

A FLASH HI absorption search in compact sources in the pilot ASKAP interplanetary scintillation field

Paris E. Gordon-Hall, Emily F. Kerrison, Elizabeth K. Mahony, Elaine M. Sadler, Hyein Yoon, J. N. H. S. Aditya, James R. Allison, Rajan Chhetri et al.

In this pilot study, we use data from the First Large Absorption Survey in HI (FLASH) to search for redshifted HI 21cm absorption at $0.4<z<1$ towards 157 bright radio sources with Interplanetary Scintillation (IPS) measurements at 820MHz in a single field observed with the Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope. The ASKAP IPS measurements, which use only 2.5 minutes of observing time in total, allow us to estimate the compactness of these radio sources on sub-arcse…

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astro-ph.GA

Environmental Imprints on the Assembly of the Cool Gas around Bright Cluster Galaxies

Runyu Zhu, Hu Zou, Taotao Fang, Enci Wang, Zeyu Chen, Zhaobin Chen, Weiyu Ding, Jinfu Gou et al.

Galaxy clusters represent extreme cosmic laboratories where environmental processes dramatically reshape their constituent galaxies, yet their effect on the gaseous halos of central galaxies remains poorly constrained. Here we present the first statistical mapping of cool gas around massive brightest cluster galaxies (BCGs) at $z\approx0.55$. Using Mg II absorption in stacked sight-line spectra from over a million background quasars observed by the Dark Energy Spectroscopic Instrument, we compar…

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astro-ph.SR

Pulsation harmonics reveal the origin of the century-old Blazhko effect

Jia-Shu Niu

The Blazhko effect -- a quasi-periodic modulation of pulsation amplitude and phase observed in all subtypes of RR Lyrae stars -- has defied physical explanation for over a century. Here we show that pulsation harmonics of the Blazhko RRab star V783 Cyg, traditionally regarded as passive replicas of the fundamental mode, encode a direct observational signature of the effect's origin. Using Kepler short-cadence photometry, we identify a subset of harmonics -- here termed ``disharmonized harmonics'…

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astro-ph.HE

Pulsar anti-glitches: starquakes driven by magnetism?

Hanyuan Long, Ruipeng Lu, Weiyang Wang, Shunshun Cao, Hao Tong, Han Yue, Renxin Xu

In the conventional starquake model of pulsar glitches, it is usually assumed that such events arise from fault slip induced by the self-gravity of compact objects. This inevitably decreases the moment of inertia, producing a glitch with an amplitude of only $Δν/ν> 0$. However, an increasing number of anti-glitches ($Δν/ν< 0$) have been observed in extremely magnetized pulsars, the magnetars, and this cannot be explained by that framework. In the present study, we hypothesis that magnetic stress…

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astro-ph.GA

Testing the recovery of the NGC 6505 Einstein ring in deep OSN 1.5-m imaging

Homer Dávila Gutiérrez, Julio Carlos Bertua Marasca, Alejandro Heredia Teva, Irene Naranjo Arroyo, Fernando Núñez Martínez, Miguel Ruiz Travesí, Eugenio Grande Sáez

The discovery of a complete Einstein ring around the nearby elliptical galaxy NGC 6505 (z = 0.042) by the Euclid mission provides a rare, precisely characterised low-redshift strong lens. Its Einstein radius of 2.500 arcsec is comparable to the angular resolution attainable from typical mid-aperture ground-based facilities, which makes the recoverability of the ring from the ground an open practical question. We test whether the ring can be recovered in deep Cousins-R imaging of NGC 6505 obtaine…

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physics.plasm-phphysics.space-ph

Exact Solution of the Direct and Inverse Dynamo Problem in the Expanding Plasma Ball

Yurii V. Dumin

It was found that the differential equation of dynamo effect (i.e., generation of the electric fields and currents) in a uniformly-expanding plasma ball with strongly anisotropic conductivity possesses the unique mathematical property: namely, the spectrum of its eigenvalues is universal and independent of physical parameters of the medium. As a result, it becomes possible to introduce a special set of eigenfunctions - which we called the generalized spherical functions - that can be used to sol…

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physics.ao-phastro-ph.EPnlin.AO

Modeling the response of the marine carbon cycle to extreme CO$_2$ injection events

Punit Gandhi, Rowan Lockwood, Corinne Myers, Parimita Roy, Ivan Sudakow, James Witts, Hao Helen Zhang

We explore how the response of a conceptual model of the marine carbon cycle depends on the way in which carbon is injected from the atmosphere. We find that, for single-injection pulses, the threshold amount required for a large response of the excitable system depends on pulse duration but not on its specific form. We do, however, see differences in the number of large transient responses in carbon and, correspondingly, the duration of the response for different pulse shapes. These differences…

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astro-ph.GA

A differentiable hydrodynamical approach to the Milky Way bar pattern speed with CO longitude--velocity data

Junichi Baba, Kohei Hattori

We present a differentiable hydrodynamical framework for modeling barred gas flow in the Milky Way and constraining broad low-loss regions in bar-pattern-speed parameter space from Galactic longitude--velocity data. The method evolves a neutral-gas disk in a fixed barred potential, projects it into longitude--velocity ($\ell$--$v$) space, and compares predicted and target maps using a cosine-distance loss applied to processed and masked maps. This emphasizes large-scale morphology rather than th…

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astro-ph.GA

Discovery of a gravitational arc candidate at photometric redshift 4.4 in MACS J0308.9+2645 from a catalogue-based search of JWST imaging

Homer Dávila Gutiérrez

We report a strong gravitational arc (A1) in the massive Reionization Lensing Cluster Survey (RELICS) cluster MACS J0308.9+2645 (z_l = 0.356), identified in public JWST/NIRCam imaging from programme GO-5293. A1 is an extended, curved, tangentially aligned source (axis ratio a/b = 6.5, catalogue length 3.9 arcsec) located 50.9 arcsec from the cluster X-ray centre. Its six-band (1.15-4.10 micron) photometry yields a photometric redshift of z_phot = 4.4 (+0.1/-0.3), with P(z > 3) = 0.99. Using the…

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astro-ph.IM

The Interstellar Laser Beacons Hypothesis and the Cosmic Lighthouses Project

Daniel Apai, Chia-Lung Lin, Kevin Wagner

In this paper, we argue that in a realistic, resource-limited scenario senders whose intent is to maximize successful communication at the lowest cost will utilize very long-lived, pulsed beacons. Further, we argue that mass-producible laser beacons with simpler technology ($μ$s or ms pulses instead of ultrashort fs pulses) are more optimal if placed on interstellar orbits. Our extensive, existing surveys are mostly blind to the $μ$s/ms-second universe and to such beacons. We show, however, that…

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astro-ph.EP

TESS Photometry and Radial Velocity Analysis of the sub-Neptune Exoplanet π Mensae c and the Wider π Mensae Planetary System

Skylar S. Larsen, Jake D. Turner, Nikole K. Lewis, Maryame El Moutamid, Diana Solano-Oropeza, Lili Alderson, V. Abby Boehm, Daniel A. Yahalomi et al.

Exoplanet characterization relies on precise measurements of planetary orbital and physical parameters. This is particularly important for planetary dynamics and atmospheric evolution, as orbital parameters help constrain system evolution, resolve ambiguities, and gauge atmospheric retention. The first exoplanet discovered by the Transiting Exoplanet Survey Satellite (TESS), $π$ Men c, is a warm sub-Neptune orbiting a bright Sun-like star in a system containing (at least) one other planet with a…

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astro-ph.GAastro-ph.HE

Illuminating M82: Simulating X-ray Emission from Galactic Winds in a Starburst Galaxy

Allison Lin, Lachlan Lancaster, Viraj Pandya, Drummond B. Fielding, Greg L. Bryan, John A. ZuHone, Sebastian Lopez, Laura A. Lopez et al.

We generate mock X-ray observations from a suite of idealized high-resolution ($\sim 4$ pc), tall-box ($\sim 2 \times 2 \times 8$ kpc$^3$) simulations of star formation driven galactic winds in an M82-like system, varying the spatial resolution as well as the strength and distribution of supernova (SN) energy injection. We compare our mock X-ray observations with deep Chandra observations of the hot plasma around M82. While the simulated total X-ray luminosity, $L_X$, increases with resolution a…

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astro-ph.EPastro-ph.GA

MOA-2020-BLG-108Lb: A Giant Planet Beyond the Snow Line of a Low-Mass Lens Near the Lower Boundary of the Mass-Ratio Desert

Yuki K. Satoh, David P. Bennett, Takahiro Sumi, Ian A. Bond, Nicholas J. Rattenbury, Daisuke Suzuki, Naoki Koshimoto, Shota Miyazaki et al.

We present an analysis of the microlensing event MOA-2020-BLG-108, which was discovered in June 2020 by the MOA collaboration toward the Galactic bulge. The observed light curve shows significant deviations from the standard single-lens single-source model. We find two degenerate binary-lens single-source solutions, corresponding to the wide and close configurations, with a companion-to-host mass ratio of $q\sim0.02$ and projected host--companion separations of $s=1.33\pm0.01$ and $s=0.76\pm0.01…

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astro-ph.GA

Tracing cosmic star formation history through radio continuum spectral energy distribution and non-thermal emission

Fangxia An, Fatemeh S. Tabatabaei, Nick Seymour, Maryam Khademi, Zunli Yuan, Wenjie Wang, Joe A. Grundy, Mark T. Sargent et al.

As a tracer of massive star formation unaffected by dust, the radio continuum emission provides a unique window into the formation of the first stars and galaxies in the Universe. Recent observations show that the integrated rest-frame mid-radio (~1-10 GHz) luminosity of galaxies serves as one of the most robust tracers of the star formation rate (SFR). These studies further demonstrate that the synchrotron spectral index and the shape of the radio spectral energy distribution (SED) evolves with…

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astro-ph.EPastro-ph.SR

I Can Do It With A Broken Planetesimal: Characterising the planetary debris in heavily polluted cool white dwarfs

Anna-Maria Cutolo, Boris T. Gänsicke, Andrew Swan, Andrew M. Buchan, Jamie T. Williams, Detlev Koester, Paula Izquierdo, Mark A. Hollands et al.

We present the analysis of four cool and strongly metal-polluted H-atmosphere white dwarfs observed with X-shooter. We compared their atmospheric parameters obtained from spectroscopy, photometry and a hybrid method, finding a difference of up to $\simeq160$ K in $T_\mathrm{eff}$, and $\simeq0.3$ dex in $\log g$, between the three analyses. We adopt the $T_\mathrm{eff}$ and $\log g$ from the photometric analysis, and subsequently measured the metal abundances of the photospheric elements from sp…

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astro-ph.GA

Determination of kinematic distances of WISE & SMGPS H II regions in the Galactic plane using SEDIGISM cloud association

Moses Langa, Mark Thompson, Andrew Rigby, Gwenllian Williams, Mubela Mutale, Cristobal Bordiu, Simone Riggi, Willice Obonyo et al.

One of the fundamental requirements for studying and understanding Galactic structure and massive star formation is accurate distances to H II regions. However, most distance assignments are hampered by kinematic distance ambiguity (KDA), sparse parallax measurements, and the large number of radio continuum sources lacking velocity and distance measurements. We present a kinematic distance determination method via cloud association, linking H II regions from the Wide-field Infrared Survey Explor…

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astro-ph.HEastro-ph.SR

Superlinear Type II Superluminous Supernovae 2017fck and 2019cmv: A Possible Origin from Interacting Thermonuclear Supernovae

Daichi Hiramatsu, Takashi J. Moriya, D. Andrew Howell, Iair Arcavi, Jamison Burke, Griffin Hosseinzadeh, Curtis McCully, Stefano Valenti et al.

Additional power sources to traditional supernovae (SNe) are necessary to account for the extreme luminosities of superluminous SNe (SLSNe). A main power source for hydrogen-rich SLSNe (SLSNe-II) is thought to be circumstellar material (CSM) interaction. However, the nature of underlying SNe and their progenitor systems remain elusive as they are hidden below strong CSM signatures. Here, we present optical photometry and spectroscopy of SLSNe-II 2017fck and 2019cmv. They are characterized by pos…

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astro-ph.HEastro-ph.IM

Mitigating the Timing Impact of Anomalous Pulse Profile Shape Variability in PSR J1713+0747 with Gaussian Component Modeling

Shania A. Nichols, Michael T. Lam, Gabriella Agazie, Anjana Ashok, Jeremy G. Baier, H. Thankful Cromartie, Kathryn Crowter, Megan E. DeCesar et al.

The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) achieves sub-microsecond timing precision for several millisecond pulsars in its pulsar timing array (PTA) with the objective of detecting and characterizing nanohertz gravitational waves. PSR J1713+0747 is one of the most precisely timed pulsars in the array, achieving sub-microsecond timing precision. However, in April 2021, PSR J1713+0747 underwent a sudden and unusual change in pulse shape that disrupted its timing s…

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