The X-ray Properties of z>4 Quasars [PDF]
, 2000 We report on a search for X-ray emission from quasars with redshifts greater than four using the ROSAT public database. Our search has doubled the number of z>4 quasars detected in X-rays from 6 to 12.
Blair A. J. +13 more
core +2 more sources
The Astrophysical Journal, 2023 We explore reprocessing models for a sample of 17 hypervariable quasars, taken from the Sloan Digital Sky Survey Reverberation Mapping project, which all show coordinated optical luminosity hypervariability with amplitudes of factors ≳2 between 2014 and ...
Tatsuya Akiba +7 more
doaj +1 more source
Redshift-weighted constraints on primordial non-Gaussianity from the clustering of the eBOSS DR14 quasars in Fourier space [PDF]
Journal of Cosmology and Astroparticle Physics, 2019 We present constraints on local primordial non-Gaussianity (PNG), parametrized through fNLloc, using the Sloan Digital Sky Survey IV extended Baryon Oscillation Spectroscopic Survey Data Release 14 quasar sample.
E. Castorina +15 more
semanticscholar +1 more source
Finding Multiply Lensed and Binary Quasars in the DESI Legacy Imaging Surveys
The Astrophysical Journal Supplement Series, 2023 The time delay between multiple images of strongly lensed quasars is a powerful tool for measuring the Hubble constant ( H _0 ). To achieve H _0 measurements with higher precision and accuracy using the time delay, it is crucial to expand the sample of ...
C. Dawes +6 more
doaj +1 more source
Determining Central Black Hole Masses in Distant Active Galaxies and Quasars. II. Improved Optical and UV Scaling Relationships [PDF]
, 2002 We present four improved empirical relationships useful for estimating the central black hole mass in nearby AGNs and distant luminous quasars alike using either optical or UV single-epoch spectroscopy.
M. Vestergaard, B. Peterson
semanticscholar +1 more source
On the link between associated MgII absorbers and star formation in quasar hosts
, 2012 A few percent of quasars show strong associated MgII absorption, with velocities (v_off) lying within a few thousand km/s from the quasar systemic redshift.
Bahcall +22 more
core +1 more source
Exploring galaxy mass profiles in strongly lensed quasars with upcoming Roman Space Telescope observations [PDF]
EPJ Web of ConferencesStrong gravitational lensing of quasars is a powerful tool for probing cosmological parameters, tracing galaxy evolution, and investigating the internal structure of quasars.
Guliqani Esmeralda +2 more
doaj +1 more source
Constraining the anisotropy of the Universe with the X-ray and UV fluxes of quasars
European Physical Journal C: Particles and Fields, 2021 We test the anisotropy in the Finslerian cosmological model with the X-ray and ultraviolet (UV) fluxes of quasars. The 2015 and 2020 compilations of quasars are used in the cosmological constraints.
Dong Zhao, Jun-Qing Xia
doaj +1 more source
A Unified, Merger-driven Model of the Origin of Starbursts, Quasars, the Cosmic X-Ray Background, Supermassive Black Holes, and Galaxy Spheroids [PDF]
, 2005 We present an evolutionary model for starbursts, quasars, and spheroidal galaxies in which mergers between gas-rich galaxies drive nuclear inflows of gas, producing starbursts and feeding the buried growth of supermassive black holes (BHs) until feedback
P. Hopkins +5 more
semanticscholar +1 more source
Subaru High-z Exploration of Low-luminosity Quasars (SHELLQs). V. Quasar Luminosity Function and Contribution to Cosmic Reionization at z = 6 [PDF]
Astrophysical Journal, 2018 We present new measurements of the quasar luminosity function (LF) at z ∼ 6 over an unprecedentedly wide range of the rest-frame ultraviolet luminosity M1450 from −30 to −22 mag.
Y. Matsuoka +46 more
semanticscholar +1 more source