Results 41 to 50 of about 111,891 (295)

A Unified, Merger-driven Model of the Origin of Starbursts, Quasars, the Cosmic X-Ray Background, Supermassive Black Holes, and Galaxy Spheroids [PDF]

open access: yes, 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]

open access: yesAstrophysical 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

Reprocessing Models for the Optical Light Curves of Hypervariable Quasars from the Sloan Digital Sky Survey Reverberation Mapping Project

open access: yesThe 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

Subaru High-z Exploration of Low-luminosity Quasars (SHELLQs). VI. Black Hole Mass Measurements of Six Quasars at 6.1 ≤ z ≤ 6.7 [PDF]

open access: yesAstrophysical Journal, 2019
We present deep near-infrared spectroscopy of six quasars at 6.1 ≤ z ≤ 6.7 with Very Large Telescope/X-Shooter and Gemini-N/GNIRS. Our objects, originally discovered through a wide-field optical survey with the Hyper Suprime-Cam (HSC) Subaru Strategic ...
M. Onoue   +16 more
semanticscholar   +1 more source

Gaia Space Mission and Quasars

open access: yesFrontiers in Astronomy and Space Sciences, 2017
Quasars are often considered to be point-like objects. This is largely true and allows for an excellent alignment of the optical positional reference frame of the ongoing ESA mission Gaia with the International Celestial Reference Frame.
Tomaž Zwitter
doaj   +1 more source

Shedding New Light on Weak Emission-line Quasars in the C iv–Hβ Parameter Space

open access: yesThe Astrophysical Journal, 2023
Weak emission-line quasars (WLQs) are a subset of type 1 quasars that exhibit extremely weak Ly α + N v λ 1240 and/or C iv λ 1549 emission lines. We investigate the relationship between emission-line properties and accretion rate for a sample of 230 ...
Trung Ha   +22 more
doaj   +1 more source

Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs). VIII. A less biased view of the early co-evolution of black holes and host galaxies [PDF]

open access: yesNippon Tenmon Gakkai obun kenkyu hokoku, 2019
We present ALMA [C ii] line and far-infrared (FIR) continuum observations of three $z \gt 6$ low-luminosity quasars ($M_{\rm 1450} \gt -25$ mag) discovered by our Subaru Hyper Suprime-Cam (HSC) survey.
T. Izumi   +26 more
semanticscholar   +1 more source

Quasar Luminosity Function at z = 7

open access: yesThe Astrophysical Journal Letters, 2023
We present the quasar luminosity function (LF) at z = 7, measured with 35 spectroscopically confirmed quasars at 6.55 < z < 7.15. The sample of 22 quasars from the Subaru High- z Exploration of Low-Luminosity Quasars (SHELLQs) project, combined with 13 ...
Yoshiki Matsuoka   +43 more
doaj   +1 more source

The Final SDSS High-Redshift Quasar Sample of 52 Quasars at z>5.7

open access: yes, 2016
We present the discovery of nine quasars at $z\sim6$ identified in the Sloan Digital Sky Survey (SDSS) imaging data. This completes our survey of $z\sim6$ quasars in the SDSS footprint.
Banados, Eduardo   +16 more
core   +1 more source

Detecting and Characterizing Young Quasars. I. Systemic Redshifts and Proximity Zone Measurements

open access: yesAstrophysical Journal, 2020
In a multiwavelength survey of 13 quasars at 5.8 ≲ z ≲ 6.5, which were preselected to be potentially young, we find five objects with extremely small proximity zone sizes that may imply UV-luminous quasar lifetimes of ≲100,000 yr.
A. Eilers   +14 more
semanticscholar   +1 more source

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