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Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.EP

The atmospheric vertical structure of Uranus and Neptune from thermochemical models: the impact of model assumptions

Thomas Douçot, Ravit Helled, Daniel Kitzmann, Ricardo Hueso, Audrey Vorburger

The composition and temperature-pressure profile of the atmospheres of Uranus and Neptune are not well-determined. As observational data are limited, we often rely on chemical equilibrium computations to infer atmospheric abundances and cloud formation. The inferred atmospheric structures, however, strongly depend on several fundamental assumptions such as the elemental abundances and ratios, the condensation properties of the assumed species, or a reference temperature for the adiabatic structu…

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astro-ph.HE

Complex Energy-Dependent Behaviour of Quasi-Periodic Oscillation Observed in GRS 1915+105

Vaibhav Sharma, Ranjeev Misra, V. Jithesh, Shivani Chaudhary, Khushi Jirawala, J S Yadav, Pankaj Jain, N J Juris et al.

We present complex energy-resolved properties of quasi-periodic oscillations (QPOs) in the black hole X-ray binary GRS 1915+105 using an observation from the LAXPC instrument onboard AstroSat. Power density spectra (PDSs) are constructed in multiple energy bands and modeled with multi-Lorentzian components to investigate the energy dependence of QPO properties. The QPO frequency shows a modest increase with energy. Dynamic PDS analysis does not reveal clear evidence for time-dependent evolution…

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astro-ph.EPastro-ph.GAastro-ph.SR

Revisiting gravitational instability in protostellar discs with improved radiative cooling models

Alison K. Young, Ken Rice, Richard Booth, Farzana Meru

Young discs are expected to be significantly more massive than those observed at $>1$ Myr and it is at this earliest stage that planet formation likely begins. Such massive discs may be susceptible to the gravitational instability (GI), therefore we need to determine the disc and stellar properties for which the GI is active to understand its role in early disc evolution and planet formation. Prior work has been limited by model assumptions and inaccuracies due to the complex nature of the therm…

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astro-ph.SR

TIC 433545934: The first 2+2 type doubly eclipsing binary with extra, mutual eclipses

Tamás Borkovits, Saul A. Rappaport, Petr Zasche, M. Mašek, H. Kučáková, T. Mitnyan, V. B. Kostov, B. P. Powell et al.

In this work we identify and photodynamically analyze TIC 433545934, the very first doubly eclipsing 2+2-type quadruple stellar system, which shows outer eclipses, too. One such outer eclipse was discovered with TESS, which triggered a special interest in this system. Most of the data for this study come from TESS observations, but we also obtained supplemental ground-based photometric measurements for this quadruple system. The eclipse timing variation curves extracted from the TESS and ground-…

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astro-ph.HE

AT 2024qfm: a luminous fast blue optical transient at a redshift of z = 0.2267 identified by Lasair-ZTF

M. Fulton, S. J. Smartt, S. Srivastav, J. H. Gillanders, J. W. Tweddle, M. E. Huber, M. Nicholl, C. R. Angus et al.

Luminous fast blue optical transients (LFBOTs) emit from x-ray to radio wavelengths, epitomised by the discovery of AT 2018cow in a host galaxy at 65 Mpc. In the following eight years eleven more have been found, at redshifts $0.075 \lesssim z \lesssim0.34$, plus one identified retrospectively from 2016. Here we present the discovery of AT 2024qfm, classified as an LFBOT in a host galaxy at $z = 0.2267 \pm 0.0002$. Its ultraviolet-to-optical luminosity and rapid 13 day fade closely match AT 2018…

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astro-ph.IM

SNIFFLES I: Intended Emission, Unwanted Emission, and Unintended Radiation from Low-Earth Orbiting Satellites Impacting Radio Astronomy from 1-26 GHz

Balthasar Indermuehle, Liroy Lourenco

We present the first results of SNIFFLES, an ongoing observational programme to characterise intended emission, unwanted emission, and unintended radiation from NGSO systems across common radio astronomy receiver bands from 1-26 GHz (L, S, C, X, and K bands). Using the Australian 22 metre Mopra radio telescope near Coonabarabran, New South Wales, with followup observations from a single dish of the ATCA interferometer and its new BIGCAT backend, we conducted 4629 tracked observations of satellit…

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gr-qcastro-ph.SR

Temperature effects on white dwarfs in modified gravity

Sofía Vidal, Aneta Wojnar, Laur Järv

In this article we analyze the effects of a finite temperature equation of state on the equilibrium structure of white dwarfs in massive Brans-Dicke theory as well as the symmetron and dilaton screening mechanisms. We compute and present the numerically obtained mass-radius relation, effective gravitational constant as well as radial profiles of the scalar field, pressure and metric within the star. We show that assuming a non-zero temperature effectively results in a larger radius while leaving…

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astro-ph.HE

Cross-spectral Analysis of the Type-C Quasi-periodic Oscillation Shoulder Component in GX 339-4

Haifan Zhu, Mariano Méndez, Pengcheng Yang, Pei Jin, Candela Bellavita, Federico García, Wei Wang, Diego Altamirano et al.

We revisit Rossi X-ray Timing Explorer (RXTE) observations of GX~339$-$4 during the rising phase of its 2006/2007 outburst and apply a joint power-density-spectrum (PDS)--cross-spectrum (CS) decomposition to the type-C quasi-periodic oscillation (QPO) region. Within this framework, the QPO region is described by a narrow QPO fundamental and a neighboring high-frequency shoulder, whose amplitudes and phase lags can be measured separately. The shoulder is first detected at MJD~54142.04, mainly thr…

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astro-ph.GA

Gal3D: Superellipsoid Modeling of Radial 3D Galaxy Structure in IllustrisTNG and EAGLE Simulations

Shuai Lu, Min Du

Galaxy morphology and structure are key tracers of galaxy formation and evolution, making accurate measurements of intrinsic three-dimensional (3D) shape essential for linking morphology to galaxy assembly and for comparing numerical simulations. We present Gal3D, a framework that reconstructs smoothed density fields from particle data and quantifies the radial 3D structure of simulated galaxies by fitting superellipsoids to iso-density surfaces. The method recovers axis ratios, orientations, ce…

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astro-ph.EP

Chondrule formation in the outer disk from the primary three-dimensional chemical composition of CM chondrules

Poula Eyðbjørnsdóttir, Anders Johansen, Elishevah van Kooten

Chondrules and their associated fine-grained rims record key processes in the early protoplanetary disk, yet the links between chondrule chemistry, morphology, and matrix complementarity remain poorly constrained. We investigate the major, minor, and trace element compositions of 66 chondrules and FGRs from the relatively unaltered CM carbonaceous chondrites Asuka 12236, Paris, and Maribo, together with their 3D morphology, using LA-ICP-MS and X-ray tomography. CM chondrules record systematic me…

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astro-ph.SR

Elemental Composition Evolution during the 2024 September 30 Solar Eruption: A Comparison of Hot and Cool Plasma Components with Solar Orbiter/SPICE, Hinode/EIS, and Chandrayaan-2/XSM

Momchil Molnar, Joseph Plowman, Amir Caspi, Ritesh Patel, Arpit Shrivastav, Tania Varesano, Don Hassler, Ryan French et al.

Solar plasma composition differs between the photosphere and corona over a range of timescales, with preferential enhancement of elements with low first ionization potential (FIP). However, the physical origin of the FIP fractionation remains incompletely understood. Furthermore, during flares, the FIP bias also exhibits rapid changes, associated with fast transport of material with different FIP biases. We present novel observations from Solar Orbiter SPICE and EUI, Hinode/EIS, and Chandrayaan-…

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astro-ph.COastro-ph.GAgr-qchep-ph

X-ray signals converted from high-frequency gravitational waves emitted by spinning light primordial black hole dark matter

Asuka Ito, Kazunori Kohri

We investigate the detectability of high-frequency gravitational waves from the superradiance of light primordial black hole dark matter through photons converted in the Galactic magnetic field. We find that the signal is significantly enhanced in the X-ray frequency range around $10^{18}$Hz. For clustered initial conditions, future X-ray observations may detect the converted photons from primordial black holes in the mass range $10^{-15}M_{\odot} \sim 10^{-13}M_{\odot}$. Our results indicate th…

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astro-ph.IM

Tropospheric Ducting Prediction based on GFS Model Data at Inyarrimanha Ilgari Bundara, the CSIRO Murchison Radio-astronomy Observatory

Balthasar Indermuehle, Hajime Suzuki

Tropospheric ducting transports terrestrial RFI over hundreds of kilometres into the ARQZWA at Inyarrimanha Ilgari Bundara, the CSIRO Murchison Radio-astronomy Observatory. We present a ducting prediction method based on vertical refractivity profiles derived from GFS data, validated against seven years of continuous spectrum monitoring between 88 MHz and 2.68 GHz. Per-transmitter basic transmission loss to the site is computed with Rec ITU-R P.452-16 above 100 MHz and Rec ITU-R P.1812-6 below i…

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astro-ph.SRphysics.space-ph

Photospheric Kelvin--Helmholtz Vortices as Possible Drivers of Coronal Heating: Implications of the DKIST Observations

Katariina Nykyri

The Daniel K. Inouye Solar Telescope (DKIST) has resolved Kelvin--Helmholtz (KH) vortices at photospheric magnetic-flux boundaries with a characteristic wavelength of 65 km. I estimate whether these vortices can supply the photospheric driver for cross-scale plasma heating through reconnection across different heights from photosphere to low-corona. Using the simulated MURaM shear, density contrast, and 500 km vertical extent, together with a representative photospheric density, gives a shear-en…

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

Are Hot Jupiters Tidally Disrupted During Stellar Main Sequence?

Qingru Hu, Wei Zhu, Yang Huang, Bowen Zhang

Once hot Jupiters (HJs) reach their very close orbits, they are expected to experience orbital decay due to tidal interactions with their host star. However, the strength of tidal dissipation is highly uncertain, and it remains an open question whether HJs are tidally disrupted during the stellar main sequence. A previous study found that HJ hosts have a smaller Galactic total velocity dispersion than their field star counterparts, which they interpreted as evidence of tidal disruption. We revis…

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astro-ph.EPastro-ph.GA

Are Near Resonant Multiple-planet Systems from Kepler Young?

Wei Zhu, Qingru Hu

Recent studies have claimed that Kepler multi-planet systems hosting near-resonant planet pairs---particularly those near second-order mean-motion resonances (MMRs)---exhibit smaller stellar velocity dispersions than the general population of Kepler planet hosts. Interpreting velocity dispersion as an age indicator, these works concluded that near-resonant systems are systematically younger. We revisit this claim, but we explicitly account for contamination by thick disk stars, which are kinemat…

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physics.space-phcs.ROmath.OC

Genetic Fuzzy System-based Control for Final Approach of Spacecraft Rendezvous and Proximity Operations

Daegyun Choi, Donghoon Kim, Henzeh Leeghim

In-space servicing has been receiving great attention to extend the operation of spacecraft with defective components. This requires rendezvous and proximity operations for a chaser to provide service to a target. This work constructs a fuzzy inference system-based controller for the chaser to reach the cooperative target on a circular orbit in the final approach phase while minimizing the energy consumption of the chaser. The offline training process performed by a genetic algorithm deals with…

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astro-ph.GA

ALMA observations of pre-JWST z ~ 10 galaxy candidates: A CO(J = 9-8) line from a ULIRG at z = 2.54 and revisit of the photometric redshifts with JWST photometry

Suzuka Arai, Yuma Sugahara, Akio K. Inoue, Takuya Hashimoto, Ken Mawatari, Yi W. Ren, Steven L. Finkelstein, John R. Weaver et al.

We present Atacama Large Millimetre/submillimetre Array (ALMA) observations targeting the [OIII]$88\,μ$m line for six $z\sim10$ galaxy candidates selected with the Hubble Space Telescope and the Spitzer Space Telescope. We detect a line ($4.5σ$) and dust continuum emission ($30σ$) in UDS_18697, while detecting neither robust line nor continuum emission in the remaining five objects. The detected line in UDS_18697 is identified as CO($J=9-8$), because follow-up James Webb Space Telescope (JWST) N…

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astro-ph.GA

SPURS: Massive Stars, Dense Gas, and Ly$α$ Escape in GN-z11 at $z = 10.6$

Zuyi Chen, Daniel P. Stark, Charlotte A. Mason, Peter Senchyna, Mengtao Tang, Keerthi Vasan G. C., Lily Whitler, Adele Plat et al.

We present ultra-deep {\it JWST} spectroscopy of GN-z11 ($z=10.6$) obtained through the SPURS Cycle 4 Large Program, providing the deepest rest-UV view yet obtained of a galaxy at $z>10$. GN-z11 was previously found to be nitrogen-enhanced with detectable Ly$α$. The SPURS spectrum reveals P-Cygni stellar wind features and broad He II emission that are jointly reproduced by stellar population models incorporating very massive stars (VMS; $>100\,M_\odot$) at low metallicity and young ages ($\lesss…

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astro-ph.GA

SPURS: Massive Stars, Dense Gas, and Ly$α$ Escape in GN-z11 at $z = 10.6$

Zuyi Chen, Daniel P. Stark, Charlotte A. Mason, Peter Senchyna, Mengtao Tang, Keerthi Vasan G. C., Lily Whitler, Adele Plat et al.

We present ultra-deep {\it JWST} spectroscopy of GN-z11 ($z=10.6$) obtained through the SPURS Cycle 4 Large Program, providing the deepest rest-UV view yet obtained of a galaxy at $z>10$. GN-z11 was previously found to be nitrogen-enhanced with detectable Ly$α$. The SPURS spectrum reveals P-Cygni stellar wind features and broad He II emission that are jointly reproduced by stellar population models incorporating very massive stars (VMS; $>100\,M_\odot$) at low metallicity and young ages ($\lesss…

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astro-ph.HEastro-ph.GA

An Evolving Leptonic Jet Model for Delayed Radio Flares in Neutrino Blazars

Alina Kochocki, Xavier Rodrigues, Nathan Whitehorn

The jets of blazar active galactic nuclei (AGN) are promising sites of hadron acceleration and subsequent neutrino production, owing to their extreme intrinsic power and high radiation density. Potential associations of IceCube neutrinos with blazars displaying delayed radio flares, such as TXS~0506+056 and PKS~1424+240, may support this scenario. However, the mechanisms and location of particle acceleration in the jet remain unclear. The 2017 IceCube event associated with TXS 0506+056 was concu…

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astro-ph.SR

Titanium Oxide Absorption as a Proxy to Detect Long term Variation and Activity Cycle in Proxima Centauri

Fatemeh Azizi, Mohammad Taghi Mirtorabi, Rahimeh Foroughi

Stellar activity cycles on magnetically active stars can be estimated by molecular absorption bands. We have previously introduced a molecular index which compares absorptional line strength of the TiO567nm with its nearby continuum has previously been introduced. In this work we use this indicator to evaluation long-term activity variations for Proxima Centauri star, using spectroscopic data from HARPS. The results indicate periodicity with an activity period of 2873(+47.4-53.9) days, which is…

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hep-phastro-ph.HEgr-qcnucl-th

Massive cold hybrid stars in a modified Polyakov-Nambu-Jona-Lasinio model

Sk Md Adil Imam, Pedro Costa, Mariana Dutra, Odilon Lourenço, Renan Pereira, Constança Providência

We propose a modified Polyakov-loop Nambu--Jona-Lasinio (mPNJL) model in which the Polyakov potential is given by an explicit dependence on the quark chemical potential, allowing it to remain finite at zero temperature and thus to describe the confinement-deconfinement transition in cold dense matter. Combining this modified quark sector with hadronic equations of state via a Maxwell construction, we find that, depending on the model parameters, the equation of state can exhibit either two phase…

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astro-ph.HEhep-phnucl-exnucl-th

How Neutron Star Radii Encode the Dense-Matter Equation of State and Hadron-Quark Transition

Bao-An Li, Xavier Grundler

We investigate how future high-precision neutron star (NS) radius measurements encode microscopic information about the dense-matter equation of state (EOS), focusing on a possible first-order hadron--quark phase transition and the resulting mass--radius topology. Within a Bayesian framework using meta-model EOSs with nine microscopic parameters, we analyze mock radius measurements $R_{1.4}=11.9\pmσ_R$ km with $σ_R=0.9$ and $0.1$ km for canonical NSs. We introduce inverse EOS--radius mappings th…

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astro-ph.GAastro-ph.COastro-ph.SR

Gaia parallax bias via spherical harmonics: A Python tool and discussion of possible causes

Valeri V. Makarov, Ciprian T. Berghea

Parallaxes in Gaia DR3 are known to suffer from a complex set of sky-correlated and magnitude-dependent offsets or biases at the level of a few tens of $μ$as. Estimated from a sample of one million distant quasars and AGNs from the CRF catalog, the average offset is negative, but the actual distribution of this important parameter shows significant variations on the sky. We propose a practical method to evaluate the parallax correction as a function of sky position and, optionally, of $G$ magnit…

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astro-ph.SRphysics.plasm-phphysics.space-ph

The Wave-Regulated Precursor of a Near-Parallel Interplanetary Shock Observed by Parker Solar Probe

Immanuel Christopher Jebaraj, Lucas Colomban, Oleksiy Agapitov, Michael Gedalin, Mikhail Malkov, Athanasios Kouloumvakos, Edin Husidic, Shiladittya Mondal et al.

Diffusive shock acceleration, at shocks from coronal mass ejections to supernova-remnant blast waves, presupposes a scattering wave field that the accelerated particles themselves maintain. This self-regulation has not been resolved in situ. We report Parker Solar Probe observations of a fast (~2800 km/s), near-parallel interplanetary shock at 0.24 AU on 2023 March 13 and separate its upstream wave field into four families, a classification not made before at a fast shock near the Sun. Right-han…

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astro-ph.IMphysics.optics

Laser-micromachined silicon-platelet feedhorns for large-scale submillimeter and millimeter-wave focal planes

Jason E. Austermann, James Beall, Andrew Forsman, Haibo Huang, Johannes Hubmayr, Matthew A. Koc, Jeff van Lanen, Pavel Lapa et al.

We present the fabrication and characterization of the first silicon-platelet feedhorn arrays produced using laser micromachining. First, we present a demonstration of the technology for the millimeter-wave band of 80~GHz to 170~GHz, i.e. covering the 90/150~GHz bands typical of CMB experiments. Next, we expand the technology to large-scale production on 150~mm wafers and demonstrate operation at submillimeter wavelengths. This feedhorn array is optimized for operation in a band centered at 350~…

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astro-ph.GA

Observing Co-Located Neutral and Ionized Gas-Phase Iron Depletion in the Magellanic Clouds

Yun Qi Li, Jessica K. Werk, Caleb R. Choban, Julia Roman-Duval, Kirill Tchernyshyov, J. Xavier Prochaska, Doyeon A. Kim, Arianna S. Long et al.

Depletion is the observed phenomenon where gas-phase elemental abundances are reduced through accretion onto dust grains. We measure neutral gas-phase elemental abundances (S, Fe) in the Magellanic Clouds along 33 sightlines using high-resolution UV spectroscopy (HST/COS and HST/STIS), and compare them to ionized gas-phase abundances (S, Fe) adopted from the literature for six co-located H\,\textsc{ii} regions (with the furthest separation of $\lesssim3'$, 50 pc). Comparing S abundances show tha…

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astro-ph.SRastro-ph.HEphysics.flu-dynphysics.plasm-phphysics.space-ph

Large-Scale Dynamos Driven by Shear-Flow-Induced Jets

B. Tripathi, A. E. Fraser, P. W. Terry, E. G. Zweibel, M. J. Pueschel, R. Fan

At every scale they occupy, magnetic fields affect various phenomena, including star formation, cosmic ray transport, charged particle acceleration, space weather, transport in planetary atmospheres, and laboratory plasmas. These fields are often generated and sustained by turbulent flows in a process called the dynamo. In 1955, E. N. Parker parameterized the effects of small-scale turbulence to propose a mean-field dynamo theory. The widely used theory reproduces observed large-scale fields but…

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astro-ph.HE

3D Radiative Transfer of Lyman-series Lines with SKIRT

N. Sameshima, A. Lauwers, B. Vander Meulen, M. Tsujimoto, L. -Y. Gu, M. Baes, P. Camps

Context. High-resolution X-ray spectroscopy and polarimetry provided by XRISM and IXPE offer new diagnostics of the geometry and kinematics of photo-ionised plasmas around compact objects. Interpreting reprocessed X-ray emission in such systems requires full three-dimensional radiative transfer (3D RT) including photon-ion interactions. Aims. We extend the Monte Carlo (MC) RT code SKIRT by implementing the Lyman-series lines of H-like ions, enabling self-consistent modelling of resonance scatter…

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