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Exploring Changes in Quasar Spectral Energy Distributions across C IV Parameter Space
Gallagher, Sarah C.; Richards, Gordon T.; Shemmer, Ohad +4 more
We examine the UV/X-ray properties of 1378 quasars in order to link empirical correlations to theoretical models of the physical mechanisms dominating quasars as a function of mass and accretion rate. The clarity of these correlations is improved when (1) using C IV broad emission line equivalent width (EQW) and blueshift (relative to systemic) va…
Spatially resolved gas flows around the Milky Way
Fox, Andrew J.; Bordoloi, Rongmon; Clark, Sean
We present spatially resolved measurements of cool gas flowing into and out of the Milky Way (MW), using archival ultraviolet spectra of background quasars from the Hubble Space Telescope/Cosmic Origins Spectrograph. We co-add spectra of different background sources at close projected angular separation on the sky. This novel stacking technique dr…
The Obscured Fraction of Quasars at Cosmic Noon
Sawicki, Marcin; Schramm, Malte; Gwyn, Stephen +6 more
Statistical studies of X-ray selected active galactic nuclei (AGN) indicate that the fraction of obscured AGN increases with increasing redshift, and the results suggest that a significant part of the accretion growth occurs behind obscuring material in the early universe. We investigate the obscured fraction of highly accreting X-ray AGN at aroun…
The Relation between the Mass Accretion Rate and the Disk Mass in Class I Protostars
Kóspál, Ágnes; Fiorellino, Eleonora; Cruz-Sáenz de Miera, Fernando +5 more
Evidence of a relation between the mass accretion rate and the disk mass is established for young, Class II pre-main-sequence stars. This observational result opened an avenue to test theoretical models and constrain the initial conditions of disk formation, fundamental in the understanding of the emergence of planetary systems. However, it is bec…
K2 Photometry on Oscillation Mode Variability: The New Pulsating Hot B Subdwarf Star EPIC 220422705
Ma, Xiao-Yu; Zong, Weikai; Fu, Jian-Ning +4 more
We present an analysis of oscillation mode variability in the hot B subdwarf star EPIC 220422705, a new pulsator discovered from ~78 days of K2 photometry. The high-quality light curves provide a detection of 66 significant independent frequencies, from which we identified nine incomplete potential triplets and three quintuplets. Those g- and p-mu…
Simultaneous Observations of Chromospheric Evaporation and Condensation during a C-class Flare
Li, Dong; Hong, Zhenxiang; Ning, Zongjun
We explored simultaneous observations of chromospheric evaporation and condensation during the impulsive phase of a C6.7 flare on 2019 May 9. The solar flare was simultaneously observed by multiple instruments, i.e., the New Vacuum Solar Telescope (NVST), the Interface Region Imaging Spectrograph, the Atmospheric Imaging Assembly (AIA), Fermi, the…
Gaia EDR3 bright star parallax zero-point using stellar clusters
Flynn, C.; Sekhri, R.; Venville, T. +4 more
We examine the zero-point of parallaxes in the Gaia EDR3 (Early Data Release 3, Gaia Collaboration (2021a)), using stars in open and globular clusters. Our aim is to check for zero-point systematics between bright stars G < 12 (which includes some important distance scale calibrators) and faint stars G > 14, for which the parallax scale has …
Radial and Local Time Variations in the Thickness of Jupiter's Magnetospheric Current Sheet
Hospodarsky, G. B.; Khurana, K. K.; Paranicas, C. P. +1 more
The magnetic field observations from the Galileo, Ulysses, Voyager 1 and 2, and Pioneer 10 and 11 spacecraft are analyzed to understand the structures and thickness of the Jovian magnetospheric current sheet. Using a new technique that can determine the motion of the spacecraft relative to the current sheet, we have built the first global map of t…
X-Ray Reverberation Mapping of Ark 564 Using Gaussian Process Regression
Ingram, Adam; Reynolds, Christopher S.; García, Javier A. +15 more
Ark 564 is an extreme high-Eddington narrow-line Seyfert 1 galaxy, known for being one of the brightest, most rapidly variable soft X-ray active galactic nuclei (AGN), and for having one of the lowest temperature coronae. Here, we present a 410 ks NuSTAR observation and two 115 ks XMM-Newton observations of this unique source, which reveal a very …
Blanco DECam Bulge Survey (BDBS). V. Cleaning the foreground populations from Galactic bulge colour-magnitude diagrams using Gaia EDR3
Rich, R. Michael; Kunder, Andrea; Johnson, Christian I. +8 more
Aims: The Blanco DECam Bulge Survey (BDBS) has imaged more than 200 square degrees of the southern Galactic bulge, providing photometry in the ugrizy filters for ∼250 million unique stars. The presence of a strong foreground disk population, along with complex reddening and extreme image crowding, has made it difficult to constrain the presen…