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Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.HEhep-phnucl-th

Estimating amplitude of matter density fluctuations in solar and supernova models using neutrino flavor evolution

Caroline Laber-Smith, Hansen Torres, Lily Newkirk, Dhriti Rathod, A. Baha Balantekin, Amol V. Patwardhan

Neutrinos can undergo substantial flavor evolution between their production in astrophysical sources-such as the Sun and core-collapse supernovae-and their subsequent detection in terrestrial detectors. This flavor evolution is strongly influenced by the environment that the neutrinos interact with, making them useful astrophysical messengers capable of potentially carrying information about the properties of the source wherein they are produced. In this work, we apply the framework of statistic…

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astro-ph.IMastro-ph.EP

Segment-level thermal sensitivity analysis for exo-Earth coronagraphy with segmented space telescopes

Ananya Sahoo, Laurent Pueyo, Iva Laginja, Bryony F. Nickson, Leonid Pogorelyuk, Laura E. Coyle, Rémi Soummer, Matthew East et al.

Direct imaging and characterization of Earth-like planets require ultra-stable wavefronts to achieve a starlight suppression level of 100 parts per trillion (ppt) in the coronagraphic dark region of the host star. Thermal drifts in the telescope may affect the wavefront stability. In this context, we present a segment-level thermal stability error budget for segmented space telescopes crucial to Earth-like planet detection and specify requirements for an ultra-stable telescope. Our study utilize…

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astro-ph.EP

Kilometre-scale Jovian moon characterized for a potential JUICE flyby

Juan Luis Rizos, Jose Maria Gomez-Limon, Yucel Kilic, Altair R. Gomes-Junior, Jose Luis Ortiz, Nicolas Morales, Alvaro Alvarez-Candal, Pasquale Palumbo et al.

Jupiter's irregular satellites are thought to be relics of early Solar System planetesimals. However, their small sizes, large distances from Earth and close angular proximity to Jupiter make them difficult to characterize remotely. Here we report multi-instrument observations of kilometre-sized Kallichore, the only irregular moon of Jupiter amenable to a close flyby by ESA's Jupiter Icy Moons Explorer (JUICE), whose astrometric and physical properties were still poorly constrained. We used Hubb…

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astro-ph.COastro-ph.HEgr-qc

Understanding constraints on primordial mass black holes made of dark matter using fast radio bursts

Surajit Kalita, Shruti Bhatporia, Amanda Weltman

In recent decades, a multitude of modified gravity theories have been proposed to address a variety of cosmological and astrophysical problems. While many of these theories remain viable, observational constraints on their parameters are increasingly stringent. Fast Radio Bursts (FRBs), in particular, have emerged as powerful probes of cosmology and fundamental physics. This study investigates the implications of a generic modified gravity theory for gravitational lensing by FRBs. By analyzing t…

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astro-ph.GA

JWST's Constraints on the Substellar IMF in NGC 2024

K. L. Luhman

A recent study has reported the detection of a turnover in the initial mass function (IMF) below 12 Mjup and the possible detection of a minimum mass near 3 Mjup in the heavily embedded cluster NGC 2024 ( =2 Mjup for Ak>=1), so the minimum mass of the IMF has not been detected. It is not possible to measure a reliable substellar IMF from the NIRCam images because of the small number of brown dwarfs encompassed by them, a bias against objects at lower masses due to the high extinctions, and incom…

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gr-qcastro-ph.IM

Ab Initio Real-Time Gravitational-Wave Parameter Estimation

David Yallup, Metha Prathaban, James Alvey, Thomas C. K. Ng, Thibeau Wouters, Nikhil Sarin, Will Handley

We present a specialised GPU-native nested sampling kernel targeting rapid parameter estimation for gravitational wave inference problems. Building upon a Slice-within-Gibbs (SwiG) structure for rapid mixing, we investigate how far we can push baseline stochastic sampling techniques on modern GPU hardware. We demonstrate that for typical long-duration binary neutron star signals observed by the LIGO and Virgo detectors, we can achieve well calibrated posterior inference on the full uncompressed…

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astro-ph.IM

Exploring generative design AI tools for astronomical instrumentation: a CubeSat chassis case study

Younes Chahid, Tassos Aretos, Will Cochrane, Katherine Morris, David Isherwood, Zeshan Ali, Graham Wilks, Noah Schwartz et al.

Generative design artificial intelligence (AI) tools are currently used in multiple scientific fields, yet their adoption in mechanical engineering computer-aided design (CAD) remains limited due to a lack of disseminated case studies, limited availability of accessible tools, insufficient training in CAD data, the absence of universal editable file formats and more. Mechanical design for astronomical instrumentation faces increasing complexity in thermal, vibrational, and mechanical requirement…

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physics.geo-phastro-ph.EP

Calibrated uncertainty for wide-angle crustal models: how firmly is the Dharwar Craton Moho actually constrained?

Deepak Kumar, Laxmidhar Behera, Wojciech Czuba

Depth uncertainties for wide-angle crustal models are usually obtained by propagating an assumed picking error, yet picks from one shot gather are mutually dependent and velocity-depth trade-offs act at the level of the model class. We revisit the 210-km Perur-Chikmagalur profile across the Dharwar Craton using a permanently identified ledger of 2,000 primary P1-P2 first arrivals and 9,919 reflections from seven shots, with 852 later-turning P4 observations held aside for a conditional test. At…

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astro-ph.HE

Multiwavelength study of supernova remnants in the Circinus constellation with SRG/eROSITA

A. Khokhriakova, W. Becker

Supernova remnants (SNRs) are key tracers of stellar feedback and the chemical and dynamical evolution of the interstellar medium. However, identifying SNRs in complex regions remains challenging, particularly when only archival multi-wavelength data are available. We aim to search for previously unrecognized SNR candidates in the Circinus constellation by combining optical imaging, radio continuum data, and available SRG/eROSITA all-sky survey X-ray observations, to provide a prioritized list o…

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astro-ph.GA

Searching in HI for Massive Low Surface Brightness Galaxies: II. Completing the UGC Sample

Karen O'Neil, Wim van Driel, Stephan Schneider

Although Low Surface Brightness (LSB) galaxies are increasingly well studied, considerable uncertainty still exists as to both their range in properties and their evolutionary history. LSB galaxies provide a fascinating extreme in galaxy formation and evolution, allowing excellent tests of galaxy formation and evolution theories. Previously, our group successfully measured the HI gas and dynamical mass properties of 350 LSB galaxies, significantly increasing the number of known extreme LSB galax…

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astro-ph.GA

Bipolar HII regions Produced by Cloud-Cloud Collisions

Theotokis Georgatos, Anthony P. Whitworth, Richard Wünsch, Annie Zavagno

We use numerical experiments to explore two possibilities: (i) that Bipolar H II Regions are the result of Cloud-Cloud Collisions (CCCs), and (ii) that -- when allowance is made for the chaotic nature of such collisions, the short duration of the bipolar phase, and different viewing angles -- a large proportion of all H II Regions might be the aftermath of CCCs. To reduce the parameter space, our experiments only consider head-on collisions between two $500$ M$_\odot$ clouds, with three differen…

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astro-ph.SR

Detecting Solar-Like Oscillations in the Highest Mass TESS Giants

Noah J. Downing, Madeline Howell, Marc H. Pinsonneault, Rafael A. García, Dinil B. Palakkatharappil, Lina Borg, Savita Mathur

Red-giant asteroseismology yields precise stellar parameters, making it a powerful tool for studying stellar structure and evolution, as demonstrated by the Kepler mission. However, due to Kepler's limited field of view, it primarily sampled the more populous low-mass red giants found outside of the Galactic plane, leading to limited detections of red giants above $\rm 3\ M_{\odot}$. Here we use the all-sky TESS data to isolate 227 intermediate-mass candidates from large catalogs with a pre-sele…

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astro-ph.COastro-ph.GA

A study of the large-scale formation in the environment of A3266: Infalling groups, filaments, and a premerger cold front

J. Dietl, A. Veronica, T. H. Reiprich, F. Pacaud, Y. Zhao, J. S. Sanders, B. Seidel, M. C. H. Yeung et al.

Abell 3266 (A3266) is a dynamically active galaxy cluster embedded in a dense environment of galaxy groups and clusters at similar redshift. Data from the Spektrum Roentgen Gamma (SRG)/eROSITA all-sky survey enable the study of faint X-ray emission in cluster outskirts. We investigate the previously unexplored outskirts of A3266 out to $3R_{100}$, characterize its nearest neighboring galaxy group, and search for connecting filaments using X-ray emission and galaxy number density. We performed X-…

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astro-ph.HE

The First Measurement of Jet Collimation Profiles in an X-ray Binary: the Case of SS 433

Xi Yan, Lang Cui, Zsolt Paragi, Sándor Frey

While significant progress has been achieved in active galactic nuclei (AGN), jet collimation profiles in X-ray binaries (XRBs) have not been directly measured. Here we report the first measurement of jet collimation profiles in an XRB using very long baseline interferometry data from SS 433. The approaching jet exhibits a well-constrained quasi-parabolic profile in the 1995 and 1998 data, whereas the prominent local oscillations present in the 2000 jet-width measurements preclude a robust chara…

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astro-ph.HE

The First Measurement of Jet Collimation Profiles in an X-ray Binary: the Case of SS 433

Xi Yan, Lang Cui, Zsolt Paragi, Sándor Frey

While significant progress has been achieved in active galactic nuclei (AGN), jet collimation profiles in X-ray binaries (XRBs) have not been directly measured. Here we report the first measurement of jet collimation profiles in an XRB using very long baseline interferometry data from SS 433. The approaching jet exhibits a well-constrained quasi-parabolic profile in the 1995 and 1998 data, whereas the prominent local oscillations present in the 2000 jet-width measurements preclude a robust chara…

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astro-ph.EP

Characterizing the oxidation state of rocky exoplanets with the Large Interferometer for Exoplanets (LIFE)

Lorenzo Cesario, Tim Lichtenberg, Michiel Min, Lena Noack, Caroline Brachmann, Eleonora Alei, Sascha P. Quanz, LIFE Collaboration et al.

The oxidation state of rocky exoplanets is expected to play a fundamental role in shaping the chemical composition of their secondary atmospheres by influencing the chemical composition of volcanically released gasses. Distinguishing planetary redox states through direct atmospheric characterization would offer insight into the formation and evolution of secondary atmospheres on exoplanets and inform the background chemistry of putative biosignatures. The Large Interferometer For Exoplanets (LIF…

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astro-ph.HEastro-ph.GAastro-ph.SRnucl-th

Impact of Kaon Condensation on the Thermal Evolution of the CCO in HESS J1731--347 Supernova Remnant

D. G. Nanopoulos, P. S. Koliogiannis, V. Petousis, M. Veselsky, Ch. C. Moustakidis

Recent analyses of the central compact object in the HESS J1731--347 supernova remnant suggest an unusual combination of a low mass and small radius, while its thermal emission indicates a relatively high surface temperature at its estimated age. Reconciling these structural and thermal properties within a unified theoretical framework may provide important constraints on the equation of state and composition of dense matter. In this work, we investigate the thermal consequences of negatively ch…

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astro-ph.SR

Magnetic Field Stratification in Active-Region Plage from Ca II K and Ca II 8542 Å Spectropolarimetry

Iñigo Juanikorena Berasategi, Ernest Alsina Ballester, Javier Trujillo Bueno, Francisco A. Iglesias, Yusuke Kawabata, Juan Sebastián Castellanos Durán, Masahito Kubo, Alex Feller et al.

We investigate the height variation of the line-of-sight (LOS) magnetic field in solar active-region (AR) plage from the upper photosphere to the upper chromosphere using co-spatial ultraviolet (UV) and infrared (IR) spectropolarimetric observations from the Sunrise III stratospheric balloon flight. The Ca II K and Ca II 8542 Å lines provide complementary chromospheric diagnostics, while nearby Fe I lines sample photospheric layers. The LOS magnetic field is inferred from the intensity and circu…

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astro-ph.IM

Focal-Plane Diagnostics of Atmospheric and Dome-Induced Turbulence: Exploring techniques and applications

Begoña García-Lorenzo, Seifeldin Abouelella, Kabir Baig, Zenaida García Rodríguez, Kshitij Ghimire, Moisés Pulido Torres, Alejandro Trujillo Ramos, Jose A. Acosta-Pulido et al.

Atmospheric turbulence remains the dominant source of image degradation in ground-based astronomy. Its impact depends not only on the integrated turbulence strength but also on the wavefront spatial-coherence outer scale (\LO) and on turbulence generated within the telescope enclosure (dome seeing). While seeing, coherence time, and related parameters are routinely monitored at major observatories, measurements of \LO\ and dome-induced turbulence remain sparse, limiting our ability to predict im…

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astro-ph.SR

Back Reaction of the Untwisting Solar Corona Scars Sunspots

Chen Xing, Xin Cheng, Guillaume Aulanier, Mingde Ding

The evolution of magnetic fields in the tenuous solar corona is predominantly governed by the motions of the underlying dense photosphere. Despite, coronal magnetic restructuring driven by magnetic reconnection between interacting coronal fields can sometimes react backwards to change photospheric magnetic fields. However, the mechanism of reactions remains undetermined. Here, we report the discovery of a back-reaction phenomenon: the untwisting of coronal loops that become twisted during reconn…

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astro-ph.EP

Statistical Constraints on Albedo Structure in Asteroid Families from NEOWISE Measurements

Murat Kaplan

Interpreting asteroid family albedo distributions as compositional signatures requires distinguishing intrinsic structure from measurement artifacts, rarely quantified. We analyze 102 families using NEOWISE data with AKARI cross-validation and SDSS-based photometric checks, establishing detection limits for bimodality and quantifying selection bias in size-albedo correlations. We work primarily in logarithmic albedo space (log10 pV), which more accurately resolves the asymmetric dark/bright mixt…

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astro-ph.SR

Cataclysmic variables from SRG/eROSITA: new systems from eRASS1

A. D. Schwope, J. Brink, D. A. H. Buckley, V. A. Cúneo, S. Friedrich, S. Hernández-Díaz, K. Knauff, J. Kurpas et al.

(abridged) Aims. We aim to generate large samples of CVs selected from the SRG/eROSITA surveys to address fundamental questions about binary evolution, the role of magnetic fields in CV evolution and their contribution to the Galactic Ridge X-ray Emission (GRXE). Methods. We have trained a Random Forest (RF) classifier based on combined X-ray and optical properties to select CV candidates from the first eROSITA X-ray all-sky survey (eRASS1). Follow-up spectroscopy to securly identify the objects…

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astro-ph.GA

Angular Momentum Evolution from Core to Disk Scales in the Early Phase of Star Formation: Constraints from HH 212, HH 211, and B335

Chin-Fei Lee

I investigate the angular momentum evolution from core to disk scales in the early phase of star formation using three protostellar systems: HH 212, HH 211, and B335. Observations show that the specific angular momentum follows a power-law dependence at core scales and transitions to an approximately constant value at smaller radii, indicating dynamical collapse in the inner envelope. I model this behavior using the inside-out collapse solution of Shu (1977) and its rotating extension, the Tereb…

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

The physical origin of the maximum stellar size

Gautham N. Sabhahit, Jorick S. Vink

One might expect the most massive stars to also be the largest by size, yet they are not, and this has puzzled astronomers for decades. The Eddington limit sets an upper bound to stellar mass through the balance between radiation pressure and gravity, but a second empirical boundary on stellar radius has equally far-reaching consequences for modern Astrophysics: it affects the black-hole masses and merger rates inferred by LIGO and Virgo, determines whether a star remains a hot, compact ionising…

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

Hydrodynamical mass-loss rates for very massive stars II. New theoretical mass-loss predictions at solar metallicity (Z = 0.02)

Gautham N. Sabhahit, Jorick S. Vink, Andreas A. C. Sander

The evolutionary pathways and ultimate fates of very massive stars are governed primarily by mass loss through radiatively-driven winds. We present a new theoretical mass-loss prescription for (very) massive stars, capturing the complex dependence on the Eddington parameter $Γ_e$, luminosity, temperature, and hydrogen abundance. We calculated an extensive grid of 178 hydrodynamically consistent wind-atmosphere models in non-local thermodynamic equilibrium using the PoWR-HD code, predicting wind…

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physics.plasm-phastro-ph.SRphysics.space-ph

The Second Quadratic Invariant of Astrophysical Gyrokinetics

Benjamin D. G. Chandran, Alfred Mallet, Romain Meyrand

We show that gyrokinetics in a spatially uniform equilibrium (or `astrophysical gyrokinetics') possesses a previously unknown quadratic invariant, which we call the gyrokinetic helicity. We derive the limiting forms of the gyrokinetic helicity in five subsidiary expansions of astrophysical gyrokinetics: the isothermal electron fluid (ITEF) approximation, kinetic reduced magnetohydrodynamics (KRMHD), electron reduced magnetohydrodynamics (ERMHD), finite-Larmor-radius magnetohydrodynamics (FLR-MHD…

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astro-ph.HEhep-ph

Comparative Periodogram Analysis of 22 Years of Super-Kamiokande Solar $^{8}\mathrm{B}$ Neutrino Data: Classical, Phase-Based, and Information Theoretic Methods

Liangliang Ren, Ze-Lin Zhang, Bing Xu, Tian-Cheng Huang, Ran Wang, Jia-Xin Dong, Yan-Ping Wang

Solar $^8\mathrm{B}$ neutrinos offer a unique probe of solar interior dynamics and neutrino electromagnetic properties. We present a systematic, multi-method periodogram analysis of the 22-year Super-Kamiokande solar neutrino dataset (1996--2018), comparing nine algorithms. Through hierarchical temporal segmentation, we disentangle astrophysical signals from detector systematics. The Generalized Lomb-Scargle (GLS) method provides the most statistically robust detections by correctly handling het…

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astro-ph.HEhep-ph

Comparative Periodogram Analysis of 22 Years of Super-Kamiokande Solar $^{8}\mathrm{B}$ Neutrino Data: Classical, Phase-Based, and Information Theoretic Methods

Liangliang Ren, Ze-Lin Zhang, Bing Xu, Tian-Cheng Huang, Ran Wang, Jia-Xin Dong, Yan-Ping Wang

Solar $^8\mathrm{B}$ neutrinos offer a unique probe of solar interior dynamics and neutrino electromagnetic properties. We present a systematic, multi-method periodogram analysis of the 22-year Super-Kamiokande solar neutrino dataset (1996--2018), comparing nine algorithms. Through hierarchical temporal segmentation, we disentangle astrophysical signals from detector systematics. The Generalized Lomb-Scargle (GLS) method provides the most statistically robust detections by correctly handling het…

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astro-ph.GA

A search for HI absorption in distant star-forming galaxies with ASKAP-FLASH - II. Direct observations and stacking of 21 cm line

Sophie L. Eden, Elaine M. Sadler, Kevin A. Pimbblet, Stephen J. Curran, Julia Healy, Filippo M. Maccagni, Elizabeth K. Mahony, Hyein Yoon et al.

We present results of a search for associated and intervening HI 21 cm absorption in star-forming galaxies and a control sample of radio galaxies at 0.4 < $z$ < 1.0, using ASKAP's FLASH HI 21 cm absorption survey. We report the detection of a new HI 21 cm absorption line in radio galaxy NVSS J214954-004657 at $z_{\mathrm{HI}}$ = 0.863. Additionally, we present results of HI 21 cm stacking for associated and intervening star-forming and radio galaxy catalogues. For the first time at these redshif…

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astro-ph.GA

Invariant manifolds in barred galaxy simulations. III. Self-regulated weakening of strong spiral arms

T. Soler-Terricabras, S. Roca-Fàbrega, M. Romero-Gómez

We investigated the origin of the weakening of strong spiral arms in barred galaxies, seeking the physical mechanism responsible for the decline in the fraction of manifold-trapped particles over time. We reconstructed the gravitational potential of a fully self-consistent N-body simulation of a barred galaxy using AGAMA, computed the Lagrangian points, and quantified how their spiral-induced angular displacement affects the geometry of the invariant manifolds and the associated orbital flows. W…

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