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Research Trends

Latest preprints in space engineering and astrophysics.

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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astro-ph.GA

Ripples in the OCEANS: Broad Line Variability of Little Red Dots

Madisyn Brooks, Kelcey Davis, Jonathan R. Trump, Raymond C. Simons, Erini Lambrides, Pablo Arrabal Haro, Bren E. Backhaus, Nikko J. Cleri et al.

Little Red Dots (LRDs) are a unique class of compact, red sources discovered in the JWST extragalactic deep fields. Determining if they are indeed powered by accreting supermassive black holes (SMBHs) is one of the main drivers of the intense study of these objects. Evidence for variability in these objects provides a direct test for the active galactic nucleus (AGN) nature of their central engine. In this study, we present a variability analysis of 6 LRDs observed by the $R \sim 2700$ OCEANS su…

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astro-ph.GA

CLASSY. XV. Kinematics and Spatial Distributions of Outflows in Local Highly Star-Forming Galaxies

Mason S. Huberty, Cody A. Carr, Claudia Scarlata, Alaina Henry, Matthew Hayes, Xinfeng Xu, Timothy Heckman, Karla Z. Arellano-Cordova et al.

Star-forming galaxies drive massive outflows that play an important role in galaxy evolution by regulating feedback and influencing the dynamics of surrounding media. Measuring galactic outflow rates is essential for quantifying feedback efficiency and the amount of mass, momentum, and energy deposited into the circumgalactic medium. In this paper, we examine 17 galactic outflows from the CLASSY survey with radiative transfer modeling of UV absorption lines presented in M. Huberty et al. (2024),…

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astro-ph.SR

Astronomical Cardiology II: A Search For Heartbeat Stars Using APOGEE and TESS

Jowen Callahan, D. M. Rowan, C. S. Kochanek, M. M. Fausnaugh

Stellar binaries in short-period, highly eccentric systems with significant tidal deformations near pericenter, also known as heartbeat stars, are a laboratory for studying dynamical tides and oscillations in stars. We identify 50 heartbeat stars using TESS light curves of stars identified as binaries using SDSS APOGEE. We fit their phase-folded TESS light curves with an analytic model to measure their orbital periods, eccentricities, inclinations, and arguments of periastron. We measure the mas…

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astro-ph.GA

Trace the Self-Gravitating Gas Using CO Isotopologues

Linjing Feng, Jingwen Wu, Sihan Jiao, Zhi-Yu Zhang, Junzhi Wang, Chao-Wei Tsai, Di Li, Hauyu Baobab Liu et al.

Recent studies have shown that the star formation rate (SFR) correlates tightly and linearly with the mass of gravitationally bound gas, which can be delineated from the power-law tail of the column-density probability distribution function ($N$-PDF) derived from dust emission observations. This relationship holds across four orders of magnitude within the Milky Way--spanning low-mass to high-mass star-forming regions and encompassing the extreme environment of the Central Molecular Zone. Buildi…

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astro-ph.GA

FLAGS II: Constraining Galaxy Formation Models with Dimensionality Reduction of Direct Observables

Jack C. Turner, Stephen M. Wilkins, William J. Roper, Aswin P. Vijayan

Comparisons between observations of galaxies and theoretical predictions are regularly performed using physical properties, which are inferred by the often slow and biased process of SED fitting. Forward modelling facilitates a reliable alternative, whereby models are evaluated using direct observables alone. However, these datasets become high-dimensional when collating observations from multiple telescopes, leading to sparse sampling, memory intensity and visualisation difficulties. We show th…

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astro-ph.IMstat.ML

Don't Cut Corners: How Training Outside the Prior Makes Simulation-Based Inference More Robust

Chaipat Tirapongprasert, Matthew Ho

Large astrophysical simulation campaigns often generate training data by sampling parameters across a Uniform prior box. Due to the proposal's sharp edge, neural posterior estimators struggle to learn accurate approximations near the boundaries. We propose Tailed-Uniform, a family of hybrid proposal distributions for sampling training simulations for robust simulation-based inference. By padding the original hard-truncated training box with decaying tails, Tailed-Uniform-trained networks yield m…

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astro-ph.GA

Why is GN-z11 Bright, Compact, and Nitrogen Enhanced? Insights from UV Absorption and Emission Diagnostics

Minami Nakane, Masami Ouchi

We investigate the UV spectrum of GN-z11, a luminous, compact galaxy with strong nitrogen lines, at $z=10.60$, using deep JWST/NIRSpec high-resolution IFU and medium-resolution MSA spectra assembled from the JADES, SPURS, and GO programs. After optimized reduction and extraction of the IFU data including an evaluation of statistical and systematic uncertainties, we obtain mutually consistent spectra from the high- and medium-resolution observations. After carefully accounting for the data qualit…

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astro-ph.HE

Interacting Supernovae: a Radio and X-ray Strategy to Constrain the Structure of the Circumstellar Medium

Shunke Ai, Irene Tamborra, Leonardo Dinoi

The interaction of supernova (SN) ejecta with the dense circumstellar medium (CSM) converts shock kinetic energy into radiation across multiple wavebands. We investigate the dependence of the X-ray and radio emission on the CSM geometry, considering spherical, hourglass, and disk shapes for the CSM. We find that the spectral and light-curve properties, both in X-ray and radio, significantly differ for spherical and non-spherical CSM structures. For a non-spherical CSM, the radio light curve flat…

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astro-ph.GA

Why is GN-z11 Bright, Compact, and Nitrogen Enhanced? Insights from UV Absorption and Emission Diagnostics

Minami Nakane, Masami Ouchi

We investigate the UV spectrum of GN-z11, a luminous, compact galaxy with strong nitrogen lines, at $z=10.60$, using deep JWST/NIRSpec high-resolution IFU and medium-resolution MSA spectra assembled from the JADES, SPURS, and GO programs. After optimized reduction and extraction of the IFU data including an evaluation of statistical and systematic uncertainties, we obtain mutually consistent spectra from the high- and medium-resolution observations. After carefully accounting for the data qualit…

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astro-ph.GA

Recycled Gas Dominates the Metal-rich Fuel of Supermassive Black Holes

Dongyun Kwak, Ena Choi, Hannah Jhee, Rachel S. Somerville, Thorsten Naab, Michaela Hirschmann, Jaejin Shin, Jong-Hak Woo et al.

Understanding the origin and chemical properties of gas accreted by supermassive black holes (SMBHs) is essential for linking black hole growth to galaxy evolution. Using a suite of 30 high-resolution cosmological zoom-in simulations, we investigate the chemical properties of gas accreted onto SMBHs in massive galaxies with stellar masses of $10^{10.9-11.9}\,\rm M_\odot$ and black hole masses of $10^{8.5-9.7}\,\rm M_\odot$ at $z=0$. By tracing the full cosmological histories of individual gas pa…

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astro-ph.GA

The Ĝ Infrared Search for Extraterrestrial Civilizations with Large Energy Supplies. V. When Galaxies Glow with Industry

Olivia Curtis, Aidan J. Rowland, Jason T. Wright, Caryl Gronwall, Jakob M. Helton, Joel Leja

We present the most robust stellar population synthesis (SPS)-based search for galaxy-spanning technological waste heat to date, applied to 129 nearby galaxies spanning a wide range of spectral energy distribution (SED) types, including ultraluminous IR galaxies and MIR-luminous active galactic nuclei (AGN). We incorporate the AGENT Dyson sphere formalism into the Flexible Stellar Population Synthesis code at the stellar population level, so nebular and dust emission respond self-consistently to…

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astro-ph.EP

Climates of Gl 514 b

Héctor E. Delgado Díaz, Rory Barnes, Russell Deitrick, Mario Damasso, Nathaniel Brown

The continuous discovery of exoplanets, each with distinctive stellar and planetary properties, along with the development of higher resolution ground and space telescopes has positioned climate evolution as a fundamental component of the study of habitability. In particular, the planet Gl 514 b, located within the habitable zone of an M0.5 dwarf star 7.62 pc from Earth, is a candidate for direct observations with future ground and space-based telescopes and therefore worthy of climate modeling.…

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