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Revealing the Accretion Physics of Supermassive Black Holes at Redshift z ∼ 7 with Chandra and Infrared Observations
Hennawi, Joseph F.; Fan, Xiaohui; Walter, Fabian +14 more
X-ray emission from quasars has been detected up to redshift z = 7.5, although only limited to a few objects at z > 6.5. In this work, we present new Chandra observations of five z > 6.5 quasars. By combining with archival Chandra observations of six additional z > 6.5 quasars, we perform a systematic analysis on the X-ray properties of t…
Testing the effect of H0 on fσ8 tension using a Gaussian process method
Xu, Lixin; Li, En-Kun; Du, Minghui +2 more
Using the fσ8(z) redshift space distortion (RSD) data, the $\sigma _8^0\!-\!\Omega _\mathrm{ m}^0$ tension is studied utilizing a parametrization of growth rate f(z) = Ωm(z)γ. Here, f(z) is derived from the expansion history H(z) which is reconstructed from the observational Hubble data applying the Gaussian proces…
The diffuse γ-ray background is dominated by star-forming galaxies
Krumholz, Mark R.; Crocker, Roland M.; Roth, Matt A. +1 more
The Fermi Gamma-ray Space Telescope has revealed a diffuse γ-ray background at energies from 0.1 gigaelectronvolt to 1 teraelectronvolt, which can be separated into emission from our Galaxy and an isotropic, extragalactic component1. Previous efforts to understand the latter have been hampered by the lack of physical models capable of p…
Two Young Planetary Systems around Field Stars with Ages between 20 and 320 Myr from TESS
Torres, Guillermo; Hellier, Coel; Bieryla, Allyson +46 more
Planets around young stars trace the early evolution of planetary systems. We report the discovery and validation of two planetary systems with ages ≲300 Myr from observations by the Transiting Exoplanet Survey Satellite (TESS). The $40\mbox{--}320$ Myr old G star TOI-251 hosts a ${2.74}_{-0.18}^{+0.18}\,{R}_{\oplus }$ mini-Neptune with a $4.94$ d…
Accretion Geometry in the Hard State of the Black Hole X-Ray Binary MAXI J1820+070
Zdziarski, Andrzej A.; Szanecki, Michał; Niedźwiecki, Andrzej +2 more
We study X-ray spectra from the outburst rise of the accreting black hole binary MAXI J1820+070. We find that models having the disk inclinations within those of either the binary or the jet imply significant changes of the accretion disk inner radius during the luminous part of the hard spectral state, with that radius changing from >100 to ∼1…
Black Hole Mass Measurements of Radio Galaxies NGC 315 and NGC 4261 Using ALMA CO Observations
Ho, Luis C.; Barth, Aaron J.; Buote, David A. +6 more
We present Atacama Large Millimeter/submillimeter Array (ALMA) Cycle 5 and Cycle 6 observations of CO (2-1) and CO (3-2) emission at 0"2-0"3 resolution in two radio-bright, brightest group/cluster early-type galaxies, NGC 315 and NGC 4261. The data resolve CO emission that extends within their black hole (BH) spheres of influence (rg), …
Stringent upper limit on Be star fractions produced by binary interaction
Wang, C.; Milone, A. P.; Schootemeijer, A. +2 more
Context. Binary evolution can result in fast-rotating stars through accretion of angular momentum during mass-transfer phases. These fast-rotating stars are predicted to be observable as Be stars. Current models struggle to produce a satisfactory description of Be star populations, even though numerous pieces of observational evidence indicate tha…
CON-quest. Searching for the most obscured galaxy nuclei
Greve, T. R.; Gallagher, J. S.; Onishi, K. +28 more
Context. Some luminous and ultraluminous infrared galaxies (LIRGs and ULIRGs) host extremely compact (r < 100 pc) and dusty nuclei. The high extinction associated with large column densities of gas and dust toward these objects render them hard to detect at many wavelengths. The intense infrared radiation arising from warm dust in these sources…
ACCESS and LRG-BEASTS: A Precise New Optical Transmission Spectrum of the Ultrahot Jupiter WASP-103b
Nikolov, Nikolay; Gibson, Neale P.; Wilson, Jamie +17 more
We present a new ground-based optical transmission spectrum of the ultrahot Jupiter WASP-103b ( ${T}_{\mathrm{eq}}=2484$ K). Our transmission spectrum is the result of combining five new transits from the ACCESS survey and two new transits from the LRG-BEASTS survey with a reanalysis of three archival Gemini/GMOS transits and one VLT/FORS2 transit…
A hidden population of high-redshift double quasars unveiled by astrometry
Shen, Yue; Oguri, Masamune; Lazio, Joseph +6 more
Galaxy mergers occur frequently in the early Universe1 and bring multiple supermassive black holes (SMBHs) into the nucleus, where they may eventually coalesce. Identifying post-merger-scale (that is, less than around a few kpc) dual SMBHs is a critical pathway to understanding their dynamical evolution and successive mergers2