Search Publications
Chemical Mapping of Temperate Sub-Neptune Atmospheres: Constraining the Deep Interior H2O/H2 Ratio from the Atmospheric CO2/CH4 Ratio
Yang, Jeehyun; Hu, Renyu
Understanding the planetary envelope composition of sub-Neptune-type exoplanets is challenging due to the inherent degeneracy in their interior composition scenarios. Particularly, the planetary envelope's H2O/H2 ratio, which can also be expressed as the O/H ratio, provides crucial insights into its original location relative…
A Deep uGMRT View of the Ultra-steep Spectrum Radio Halo in A521
Brunetti, G.; Santra, R.; Kale, R. +8 more
We present the first detailed analysis of the ultra-steep spectrum radio halo in the merging galaxy cluster A521, based on upgraded Giant Metrewave Radio telescope observations. The combination of radio observations (300–850 MHz) and archival X-ray data provides a new window into the complex physics occurring in this system. When compared to all p…
Enrichment by extragalactic first stars in the Large Magellanic Cloud
Li, Ting S.; Frebel, Anna; Simon, Joshua D. +8 more
The Large Magellanic Cloud (LMC) is the Milky Way's most massive satellite galaxy, which only recently (~2 billion years ago) fell into our Galaxy. As stellar atmospheres preserve the composition of their natal cloud, the LMC's recent infall makes its most ancient, metal-deficient (`low-metallicity') stars unique windows into early star formation …
What Is the Black Hole Spin in Cyg X-1?
Zdziarski, Andrzej A.; Szanecki, Michał; Dewangan, Gulab +6 more
We perform a detailed study of the black hole spin of Cyg X-1, using accurate broadband X-ray data obtained in the soft spectral state by simultaneous NICER and NuSTAR observations, supplemented at high energies by INTEGRAL data. We use the relativistic disk model kerrbb together with different models of the Comptonization high-energy tail and the…
X-Shooting ULLYSES: Massive stars at low metallicity: IV. Spectral analysis methods and exemplary results for O stars
Bouret, J. -C.; Martins, F.; Hillier, D. J. +26 more
Context. The spectral analysis of hot, massive stars is a fundamental astrophysical method of determining their intrinsic properties and feedback. With their inherent, radiation-driven winds, the quantitative spectroscopy for hot, massive stars requires detailed numerical modeling of the atmosphere and an iterative treatment in order to obtain the…
Alfvénic fluctuations in the expanding solar wind: Formation and radial evolution of spherical polarization
Hellinger, P.; Matteini, L.; Horbury, T. S. +7 more
We investigate properties of large-scale solar wind Alfvénic fluctuations and their evolution during radial expansion. We assume a strictly radial background magnetic field B ∥ R, and we use two-dimensional hybrid (fluid electrons, kinetic ions) simulations of balanced Alfvénic turbulence in the plane orthogonal to B; the simulated plasma evolves …
Cosmic evolution early release science survey (CEERS): multiclassing galactic dwarf stars in the deep JWST/NIRCam
Papovich, Casey; Finkelstein, Steven L.; Burgarella, Denis +20 more
Low-mass (sub)stellar objects represent the low end of the initial mass function, the transition to free-floating planets and a prominent interloper population in the search for high-redshift galaxies. To what accuracy can photometry only classify these? JWST/NIRCam has several advantages over Hubble Space Telescope (HST)/WFC3 near-infrared (NIR):…
Impact of the cosmic neutrino background on long-range force searches
Chauhan, Garv; Xu, Xun-Jie
Light bosons can mediate long-range forces. We show that light bosonic mediators interacting with a background medium, in particular, with the cosmic neutrino background (CνB), may induce medium-dependent masses which could effectively screen long-range forces from detection. This leads to profound implications for long-range force searches in e.g…
Analysis of the public HARPS/ESO spectroscopic archive. Ca II H&K time series for the HARPS radial velocity database
Tal-Or, L.; Perdelwitz, V.; Trifonov, T. +2 more
Context. Magnetic activity is currently the primary limiting factor in radial velocity (RV) exoplanet searches. Even inactive stars, such as the Sun, exhibit RV jitter of the order of a few m s−1 due to active regions on their surfaces. Time series of chromospheric activity indicators, such as the Ca II H&K lines, can be utilized to…
The Galaxy Activity, Torus, and Outflow Survey (GATOS). IV. Exploring Ionized Gas Outflows in Central Kiloparsec Regions of GATOS Seyferts
Bunker, Andrew J.; Imanishi, Masatoshi; Gandhi, Poshak +33 more
Utilizing JWST MIRI/Medium Resolution Spectrograph integral field unit observations of the kiloparsec-scale central regions, we showcase the diversity of ionized gas distributions and kinematics in six nearby Seyfert galaxies included in the GATOS survey. Specifically, we present spatially resolved flux distribution and velocity field maps of six …