UchUchU

研究動向

宇宙工学・惑星科学・宇宙物理の最新プレプリント。

astro-ph.GA

Discovery of four Narrow-line Type-1 Quasars at z = 2.54 -- 6.06 with Subaru 'Onohi'ula PFS-SSP

Ayumi Takahashi, Yoshiki Matsuoka, Yoshiki Toba, Tohru Nagao, Toshihiro Kawaguchi, Hiroaki Sameshima, Alberto Rodríguez-Ardila, Andy D. Goulding et al.

We report the discovery of four narrow-line type-1 quasars (NLQ1s) from the Subaru 'Onohi'ula Prime Focus Spectrograph Subaru Strategic Program (PFS-SSP). To extend a comprehensive understanding of this population to the distant universe, we searched for broad-line AGNs (quasars) whose rest-UV spectral shapes resemble those of local NLS1 galaxies, utilizing the Ly$α$ line profile. We identified four NLQ1s, including one candidate, at $z=2.54$ -- $6.06$. The obtained spectra show a prominent Ly$α…

詳細を見る →
astro-ph.IMphysics.soc-ph

Which is the best day of the week to submit to arXiv:astro-ph?

Chirag Sharma, Shantanu Desai

We examine whether the citations received by refereed astronomy papers vary systematically with the day of the week of their arXiv preprint release. We use NASA ADS citation data for all refereed articles published in 2020--2023 in six journals (MNRAS, ApJ, ApJL, ApJS, A\&A and JCAP; 37,173 papers with astro-ph primary preprints), combined with version-1 submission timestamps from the arXiv API. We group papers both by submission weekday and by the day their announcement batch appears on arXiv,…

詳細を見る →
astro-ph.GA

A cosmic collision in the making: JWST/NIRISS reveals a merging and maturing protocluster core at z~3 around a red quasar

C. Bertemes, D. Wylezalek, G. Noirot, R. Hviding, D. S. N. Rupke, N. L. Zakamska, S. Veilleux, L. Gatto et al.

We report the discovery of ``The Step'', a dense protocluster at z=3 revealed by JWST/NIRISS Wide-Field Slitless Spectroscopy (WFSS) of the field around the luminous quasar and starburst SDSSJ165202.64+172852.3. The protocluster contains at least 18 member galaxies and exhibits two substructures in the 3D position-velocity space - notably a distinctive step-like distribution, from which the nickname derives. We propose that the Step may be undergoing a merger of two haloes, which could also expl…

詳細を見る →
astro-ph.GA

Unveiling and Characterising Ubiquitous Nitrogen Enhancement in $6 \leq z \leq 10$ Galaxies with JWST Spectroscopy

Raunaq Singh Rai, Guido Roberts-Borsani

The James Webb Space Telescope (JWST) has revealed a growing number of $z>6$ galaxies with enhanced N/O ratios that challenge standard chemical enrichment frameworks. We test whether this is exclusive to extreme systems or a generic feature of $6 \leq z \leq 10$ populations through a stacking analysis of 135 galaxies with JWST/NIRSpec $R\sim1000$ spectroscopy, probing the origin of N, C and O enrichment and its dependence on recent star formation. A full-sample composite reveals prominent C III]…

詳細を見る →
astro-ph.HE

Radiative Transfer Modeling of Stripped-envelope Supernovae II: Neural Network Emulation of Light Curves

S. Karthik Yadavalli, V. Ashley Villar, Maria R. Drout, Sebastian Gomez, Miranda Pikus, Yunyi Shen

We present the first neural-network emulator of stripped-envelope supernova (SESN) lightcurves, trained on a grid of 4499 light curves simulated with the radiative transfer (RT) code sedona. Using this emulator, we show that m_ni, m_ejecta, the ejecta velocity profile, and the degree of Ni-56 mixing can all be inferred from multiband lightcurves. We find that the degeneracy between ejecta mass and ejecta velocity is substantially weaker with this emulator than in traditional semianalytical model…

詳細を見る →
astro-ph.HEastro-ph.GA

Decoding the jet of BL Lacertae using relativistic magneto-hydrodynamics

G. F. Paraschos, J. A. Kramer, I. Liodakis, S. G. Jorstad, A. P. Marscher, I. Myserlis, I. Agudo

Blazars are a highly variable subclass of active galactic nuclei, whose relativistic jet is pointed towards our line of sight at a small angle. Their variability is often characterised by multi-band flares. BL Lacertae (BL Lac), the namesake of a blazar subclass recently exhibited the highest recorded linearly polarised optical flare. We investigate the origin of this flare via very-long-baseline interferometry observations. Our analysis shows that the sweeping, helical motion of the BL Lac jet,…

詳細を見る →
astro-ph.EPastro-ph.SR

A Sulfur-Rich Atmosphere for the Young Jupiter Analog AF Lep b Reveals Significant Solid Accretion

Jerry W. Xuan, William O. Balmer, Yayaati Chachan, Jean-Baptiste Ruffio, Kazumasa Ohno, Robert J. De Rosa, Aneesh Baburaj, Eric L. Nielsen et al.

AF Lep b is one of the closest analogs to Jupiter in terms of mass ($3-4~M_{\rm{Jup}}$) and semi-major axis ($9$ AU) amenable to spectroscopic characterization. We present JWST/NIRSpec high-contrast spectroscopy of the planet from $2.85-5.3~μ$m at $R\sim3000$, which provide detections of CO$_2$, H$_2$S, CH$_4$, $^{12}$CO (and $^{13}$CO), and H$_2$O, as well as complementary JWST/NIRCam imaging that captures the planet's continuum flux from $4.0-4.7~μ$m. Combining the JWST observations with spect…

詳細を見る →
astro-ph.HE

Explaining the X-ray Precursor, Ultra-long Prompt Emission, and Week-long Decay of GRB250702B with a Jetted Micro-TDE

Fulya Kıroğlu, Taeho Ryu, Alexander Tchekhovskoy, Kyle Kremer, Daichi Tsuna, Brian D. Metzger

The longest detected gamma-ray burst, GRB250702B, exhibited seven hours of prompt $γ$-ray emission, preceded by a soft X-ray precursor ($\sim1$ day earlier) and followed by a weeks-long fading X-ray tail. Lacking an established progenitor for all three phases, we propose that this ultra-long GRB (ULGRB) is powered by a jetted micro-tidal disruption event (micro-TDE), in which a spinning stellar-mass black hole (BH) disrupts a Sun-like star and launches a relativistic jet via the Blandford-Znajek…

詳細を見る →
hep-phastro-ph.COastro-ph.EPphysics.ao-ph

Mysterious Transients in the Palomar Observatory Sky Survey (POSS-1) as profound manifestation of the Dark Matter physics

Ariel Zhitnitsky

Transient star-like objects of unknown origin have been identified in the first Palomar Observatory Sky Survey (POSS-1) as part of the Vanishing and Appearing Sources during a Century of Observations (VASCO) project. The source of the transients recorded by POSS-1 remains unknown, which is the warrant to coin the observed phenomena as Mysterious Transients (MT). We advocate an idea that the dark matter (DM) in form of the axion quark nuggets (AQN) made of standard model quarks (or antiquarks) an…

詳細を見る →
astro-ph.COastro-ph.GAastro-ph.HEgr-qc

Realization Variance of Gravitational Wave Background Anisotropies from Shot Noise for Pulsar Timing Arrays

Meng-Xiang Lin, Adam Lidz, Chung-Pei Ma

Shot-noise anisotropies in the nHz gravitational wave background (GWB) are a promising target for pulsar timing arrays (PTAs). If the nHz GWB is sourced by merging supermassive black hole binaries (SMBHBs), as current evidence suggests, the shot-noise signal is expected to be large, potentially of order unity at observing frequencies of $f \sim 1 \, \mathrm{yr}^{-1}$. In this regime, the signal is dominated by rare bright binaries, and Poisson fluctuations in the discrete SMBHB population produc…

詳細を見る →
astro-ph.SRastro-ph.EPastro-ph.GA

IPA: Morphology and Kinematics of Molecular Hydrogen Winds in Five Young Protostars across the Mass Spectrum Observed with JWST

Himanshu Tyagi, P. Manoj, Mayank Narang, S. Thomas Megeath, Robert Gutermuth, Lee Hartmann, Alessio Caratti o Garatti, Dan M. Watson et al.

Molecular winds may play a key role in governing angular momentum transport and accretion during the early evolution of protostars. We present the morphology and kinematic properties of the H$_2$ emission in five young, envelope-dominated, protostars across a broad bolometric luminosity range, from 0.2 to $10^4~L_{\odot}$, observed with the NIRSpec/IFU and MIRI/MRS onboard JWST as part of the Investigating Protostellar Accretion (IPA) program. A rich set of pure rotational lines of H$_2$, up to…

詳細を見る →
astro-ph.SRastro-ph.EP

Nascent Embedded-protostar Survey in Taurus (NEST) II: Measuring Dust Mass, Disk Size, and Gas Mass

Noshin Yesmin, Patrick Sheehan, John Tobin, Aislinn Coleman-Plante, Nicholas P. Ballering, Tyler L. Bourke, Josh Eisner, Hauyu Baobab Liu et al.

Envelope-embedded protostellar disks represent the earliest stage of protoplanetary disk evolution, but their masses and sizes are difficult to measure because disk emission is entangled with the envelope. We analyze 26 protostellar disk systems in Taurus using ALMA Band 7 (345 GHz; ~0.3'') and VLA Ka-band (33 GHz; ~0.2'') continuum observations, together with molecular-line data to constrain disk gas masses. At 345 GHz, the median flux density, dust mass, and radius are 71 mJy, 5.5 M_Mearth, an…

詳細を見る →
astro-ph.HEastro-ph.SR

Peak 'Nebular' Emission and Early Flux Excesses in Ca-strong Supernovae

C. -G. Touchard-Paxton, K. Maguire, C. Frohmaier, W. V. Jacobson-Galán, M. Pursiainen, C. Angus, J. Sollerman, A. Polin et al.

Calcium-strong supernovae (Ca-strong SNe) are a class of thermonuclear transient characterised by rapid photometric evolution (rise times of <= 16 d) and nebular-phase spectra dominated by strong [Ca II]7291,7324 emission, in comparison to the strength of [O I]6300,6364 emission. Despite their distinctive spectra and association with remote environments, their origins remain uncertain. Using new discoveries from surveys such as the Zwicky Transient Facility, supplemented by archival data, we com…

詳細を見る →
astro-ph.SRcond-mat.mtrl-sci

Infrared Spectroscopy and Photochemistry of Aromatic Nitriles in Para-Hydrogen Matrices

Sam McGrath, Vincent J. Esposito, Linshan Zeng, Thomas H. Speak, Brendan Moore, Pavle Djuricanin, Jun Miyazaki, Takamasa Momose et al.

Motivated by recent detections of several aromatic nitriles in Taurus Molecular Cloud-1, we report laboratory and theoretical investigations of the vibrational spectroscopy and photochemistry of singly and doubly cyano-substituted benzene in solid para-hydrogen matrices. We compare the photochemistry of cyanobenzene (benzonitrile) and three dicyanobenzene isomers initiated by excitations at 193 nm. In addition, we report the photochemistry of deuterated cyanobenzene (d$_5$-cyanobenzene), enablin…

詳細を見る →
astro-ph.IM

A bestiary of low-level electrical artifacts in SPHEREx flight data

Candice M. Fazar, Michael Zemcov, C. Darren Dowell, Brendan P. Crill, Chi Nguyen, Howard Hui

SPHEREx, NASA's all-sky spectrophotometric survey mission, maps the sky in 102 spectral channels from 0.75 um to 5.0 um at 6.15'' resolution from low-Earth orbit using a custom readout of six HAWAII-2RG detectors. The SPHEREx instrument team and Science Data Center have built a robust science data pipeline that includes mitigating image-space artifacts arising from low-level optical and electronic effects. Analysis of first-survey flight data has confirmed predictions for some of these effects,…

詳細を見る →
astro-ph.HE

The Galactic Neutrino Sky: Predictions from Gamma-ray Source Populations

Leo Seen, Ke Fang

High-energy neutrino emission from the Galactic plane has been detected at a significance of $5.7σ$, with a prominent excess toward the inner Galaxy. We show that this excess can be naturally explained by the spatial distribution of Galactic neutrino sources. By combining $γ$-ray source catalogs spanning GeV-PeV energies and selecting candidate hadronic emitters, we construct ReGal-$γ$, a template of resolved Galactic $γ$-ray sources that may also produce high-energy neutrinos. Compared with mod…

詳細を見る →
astro-ph.IMastro-ph.HE

NASA ASTRA Initiative White Paper: Space-Based Mission for Ultrahigh Energy Particles

Mauricio Bustamante, Johannes Eser, Ke Fang, Claire Guépin, John Krizmanic, Eric Mayotte, Keith McBride, Kohta Murase et al.

Ultra-high-energy cosmic rays ($E_{\rm CR} \gtrsim 1$ EeV) are the highest-energy particles known, signaling extreme particle processes at work in the universe. However, many aspects of their nature remain largely unknown, even after more than a century of study. Very-high-energy ($E_ν\gtrsim 1$ PeV neutrinos associated with cosmic-ray interactions, both during the acceleration process and propagation, would provide new insight into these extreme particles, as we have seen at lower energies with…

詳細を見る →
astro-ph.GA

An emerging baryon cycle in a galaxy 500 million years after the Big Bang

Shengzhe Wang, Xin Wang, Hang Zhou, Zhijie Qu, Zhaozhou Li, Yuxuan Pang, Qianqiao Zhou, Shouyi Wang et al.

The emergence of stellar feedback as a regulator of galaxy growth marks a fundamental transition in cosmic history. At early times, rapid gas accretion and collapse may induce intense star formation before feedback becomes effective, producing feedback-free starbursts. When and how such bursts subsequently develop into self-regulated baryon cycles remain observationally unknown. Here we show that Gz9p3, a merging galaxy at $z=9.311$, is caught in this transition only 500 million years after the…

詳細を見る →
gr-qcastro-ph.HEhep-ph

Probing ultralight bosons with LISA observations of spinning black hole mergers and follow-up searches of merger remnants

Ifigeneia Giannakoudi, Maxence Corman, William E. East

Ultralight bosons can trigger superradiant instabilities around rotating black holes, extracting angular momentum and leading in some cases to observable gravitational signatures. When the associated spin-down timescale is shorter than the black hole lifetimes and the spin-up timescales due to, e.g. accretion, this process imposes an upper limit on black hole spins. In addition, the formation and subsequent dissipation of boson clouds generates quasi-continuous gravitational wave emission. In th…

詳細を見る →
astro-ph.IM

SGNAX: a unified matched-filter and excess-power pipeline for gravitational-wave detector characterization

Zach Yarbrough, Olivia Godwin, Derek Davis, Gabriela González

We present SGNAX, an open-source pipeline for gravitational-wave detector characterization that delivers matched-filter and excess-power transient triggers from a single streaming dataflow graph. Built on the Stream Graph Navigator (sgn) framework, SGNAX unifies the multi-rate sine-Gaussian matched-filter search of snax and the multi-resolution Q-transform search of omicron in one Python-native package. Auxiliary channels from an interferometer are analyzed as parallel branches sharing data-read…

詳細を見る →
astro-ph.IM

Quasi-automatic software support for Gaia ground based optical tracking

S. Bouquillon, C. Barache, T. Carlucci, F. Taris, M. Altmann, A. H. Andrei, R. Smart, I. A. Steele et al.

The ESA Gaia satellite mission will create a catalog of 1 billion stars with unprecedented astrometric precision. To achieve its aim in terms of astrometric precision, a ground based optical tracking campaign (GBOT) of the satellite itself is necessary during the five years of the mission. We present an overview of the GBOT project as a whole in another contribution (Altmann et al. in SPIE category "observatory operations"). The present paper will focus more specifically on the software solution…

詳細を見る →
astro-ph.IMastro-ph.HE

Pulsar Timing Array Sensitivity to Anisotropy: Empirical Sensitivity Curves, Scaling Relations, and the Multi-Resolution Pixel Basis

Taha T. Moursy, Nihan S. Pol, Gabriella Agazie, Nikita Agarwal, Akash Anumarlapudi, Anne M. Archibald, Zaven Arzoumanian, Anjana Ashok et al.

We quantify pulsar timing array (PTA) sensitivity to anisotropy in the gravitational wave background using the cross-correlation based Fisher information matrix in the pixel and spherical harmonic bases. We use a set of simulations to empirically determine scaling relations of a PTA's sensitivity to anisotropy with the number of pulsars $N_\mathrm{psr}$ in the array, the error $δt$ on the times of arrival, the frequency $f_\mathrm{GW}$ of the gravitational waves, and the angular scale $ΔΩ$ of th…

詳細を見る →
astro-ph.HE

Exploring the multi-wavelength properties of the high energetic event ZTF20abbiixp/GRB 200524A: from prompt emission to afterglow

A. Ghosh, Dimple, K. Misra, P. Yu. Minaev, Y. Yao, D. A. Kann, M. Blazek, A. S. Pozanenko et al.

We conducted a comprehensive multi-wavelength analysis of a high energetic long-duration ZTF20abbiixp / GRB~200524A detected by \textit{Fermi} Gamma Ray Burst Monitor (GBM). Our study combines extended high-energy observations from multiple space-based observatories including \textit{Fermi} with broadband afterglow data spanning X-ray to radio wavelengths, complemented by extensive photometric and spectroscopic follow-up from several ground-based optical facilities worldwide like 3.6-m Devasthal…

詳細を見る →
astro-ph.COastro-ph.HEgr-qc

Cross-frequency SGWB anisotropy from compact topology: CMB B-mode covariance as a transfer probe

Li-E Qiang, Peng Xu

Compact spatial topology restricts the eigenmodes of primordial tensor perturbations, and the resulting discreteness can render the primordial stochastic gravitational-wave background (SGWB) anisotropic. Here we treat the CMB tensor $B$-mode covariance as a transfer-filtered measurement of that ultra-low-frequency anisotropy. Writing the normalized angular tensor-power measure as $F(k,\hat k)=1+Q(k,\hat k)$ and its nonmonopole moments as $q_{LM}(k)$, we obtain an explicit kernel that maps $q_{LM…

詳細を見る →
astro-ph.EP

TOI-7475 spectroscopic follow up - detection of a massive hot Jupiter on an eccentric orbit

Joanna Pietrucha, Jakub Jerzy Tokarek, Mateusz Witczak, Wojciech Dimitrov

We present the first spectroscopic follow-up for TOI-7475, and report the detection of a planetary-mass companion. Transits with a period of 3.25 days were observed by TESS. The dips in brightness are 0.006 mag and last approximately 4.5 hours. The host star is a spectral type F5 with a mass of approximately 1.48 M$_{\odot}$. We collected 24 high resolution echelle spectra using the PST1 telescope. Analysis of the TESS photometric data and our radial velocities was performed using the Wilson-Dev…

詳細を見る →
nucl-thastro-ph.SRnucl-ex

A Gaussian Process framework for constraining the nuclear equation of state from microscopic calculations with correlated uncertainties

Y. G. Lee, J. Kim, T. Zhao, C. Drischler

We present constraints on the nuclear equation of state (EOS) from microscopic asymmetric matter calculations at zero temperature based on chiral nucleon-nucleon and three-nucleon interactions. The constraints include the saturation point, the isospin dependence of the incompressibility, and the symmetry energy, as well as the crust-core transition density of neutron-star matter. To quantify and propagate correlated uncertainties from noisy many-body calculations to derived observables, we intro…

詳細を見る →
astro-ph.HEastro-ph.GA

Recoiling Black Holes I. Burst of Observables

Erwan Hochart, Simon Portegies Zwart

We aim to investigate the tidal disruption and gravitational wave events shortly after a massive black hole binary merges in the galactic centre and whose remnant black hole is ejected from the galaxy. Using computational methods, black holes of mass $M_{\bullet}=10^{5}$ M$_\odot$ and $4\times10^{5}$ M$_\odot$ embedded in a nuclear star cluster are kicked at velocities of $v_k=300$ and $600$ km s$^{-1}$. Systems are integrated for $0.1$ Myr using a $4$th-order Hermite scheme. The kick instantane…

詳細を見る →
astro-ph.IM

Wigner interferometry

Vladimir Lenok

Aims. This work aims to introduce a new method of interferometric measurements based on correlation of Wigner functions constructed for the fields from a distant source. Methods. This work presents theoretical studies of correlation of the Wigner functions. Numerical simulations support the findings. Results. It is shown that in comparison to the correlation of the fields, a correlation of their Wigner functions samples twice higher spatial frequencies of the source intensity distribution and ha…

詳細を見る →
astro-ph.SRastro-ph.IM

Reconstruction of ASO-S/HXI Solar Flare Hard X-ray Source Images with Physics-Constrained Deep Networks

Zou SiZhong, Liu Hui, Su Yang, Hong JunChao, Chen Wei

The Hard X-ray Imager (HXI) on board the Advanced Space-based Solar Observatory (ASO-S/Kuafu-1) reconstructs solar flare hard X-ray images from the modulated counts of 91 bi-grid sub-collimators---an underdetermined problem of recovering a high-dimensional spatial distribution from low-dimensional measurements. The conventional CLEAN algorithm relies on a point-source assumption and fragments extended flare morphologies, while existing deep-learning methods learn a data-driven mapping from count…

詳細を見る →
astro-ph.SRastro-ph.IM

Reconstruction of ASO-S/HXI Solar Flare Hard X-ray Source Images with Physics-Constrained Deep Networks

Zou SiZhong, Liu Hui, Su Yang, Hong JunChao, Chen Wei

Solar flare hard X-ray (HXR) imaging by the ASO-S/HXI instrument reconstructs source images from modulated counts of 91 bi-grid sub-collimators---an underdetermined inverse problem of recovering a high-dimensional spatial distribution from low-dimensional measurements. The conventional CLEAN algorithm relies on a point-source prior, fragments extended morphologies, and requires manual parameter tuning, while existing deep-learning methods learn a data-driven counts-to-image mapping without guara…

詳細を見る →