Results 171 to 180 of about 111,891 (295)

A Surprising Excess of Radio Emission in Extremely Stable Quasars: A Unique Clue to Jet Launching?

The Astrophysical Journal
Quasars are generally divided into jetted radio-loud and nonjetted radio-quiet ones, but why only 10% of quasars are radio-loud has been puzzling for decades.
Wen-Yong Kang, Jun-Xian Wang, Zhen-Yi Cai, Hao-Chen Wang, Wen-Ke Ren, Mai Liao, Feng Yuan, Andrzej Zdziarski, Xinwu Cao   +8 more
doaj   +1 more source

A search for quasar protoclusters at z greater than 4 [PDF]

In the CDM and many other hierarchical scenarios for the origins of large scale structure, the existence of luminous quasars at very high redshifts (z greater than 3 or 4) is difficult to understand, unless such objects form at the very highest peaks of ...
Djorgovski, S., Smith, J. D., Thompson, D.   +2 more
core   +1 more source

A Multi-Colour Survey for High-Redshift Quasars [PDF]

, 1987
S. J. Warren, P. C. Hewett, M. J. Irwin
openalex   +1 more source

EVN + MERLIN Observations of Radio-intermediate Quasars: Evidence for Boosted Radio-weak Quasars [PDF]

, 1996
Heino Falcke, Alok R. Patnaik, William Sherwood   +2 more
openalex   +1 more source

Subaru High-z Exploration of Low-luminosity Quasars (SHELLQs). XVII. Black Hole Mass Distribution at z ∼ 6 Estimated via Spectral Comparison with Low-z Quasars

The Astrophysical Journal
We report the distribution of black hole (BH) masses and Eddingont ratios estimated for a sample of 131 low luminosity quasars in the early cosmic epoch (5.6 < z < 7.0).
Ayumi Takahashi, Yoshiki Matsuoka, Masafusa Onoue, Michael A. Strauss, Nobunari Kashikawa, Yoshiki Toba, Kazushi Iwasawa, Masatoshi Imanishi, Masayuki Akiyama, Toshihiro Kawaguchi, Akatoki Noboriguchi, Chien-Hsiu Lee   +11 more
doaj   +1 more source

The PAH 7.7 μm/850 μm ratio as new diagnostics for high extinction in ULIRGs -increasing evidence for a hidden quasar in Arp 220 [PDF]

, 2001
Martin Haas, U. Klaas, S. Müller, R. Chini, I. M. Coulson   +4 more
openalex   +1 more source

Environments around Quasars at z ∼ 3 Revealed by Wide-field Imaging with Subaru HSC and CFHT

The Astrophysical Journal
We examine the local density environments around 67 quasars at z ∼ 3 by combining the imaging data of Hyper Suprime-Cam Subaru Strategic Program and Canada–France–Hawaii Telescope Large Area U -band Deep Survey over about 20 deg ^2 .
Yuta Suzuki, Hisakazu Uchiyama, Yoshiki Matsuoka, Jun Toshikawa, Stephen Gwyn, Masatoshi Imanishi, Chengze Liu, Akatoki Noboriguchi, Marcin Sawicki, Yoshiki Toba   +9 more
doaj   +1 more source

Quasar Lifetime Measurements from Extended Lyα Nebulae at z ∼ 6

The Astrophysical Journal
The existence of billion-solar-mass black holes hosted in luminous quasars within the first gigayear of cosmic history poses a challenge to our understanding of supermassive black hole (SMBH) growth.
Dominika Ďurovčíková, Anna-Christina Eilers, Romain A. Meyer, Emanuele Paolo Farina, Eduardo Bañados, Frederick B. Davies, Joseph F. Hennawi, Chiara Mazzucchelli, Robert A. Simcoe, Fabian Walter   +9 more
doaj   +1 more source

The Spectral Energy Distributions of Quasars and AGN [PDF]

, 2003
B. J. Wilkes
openalex   +1 more source

Changing-look Active Galactic Nuclei from the Dark Energy Spectroscopic Instrument. V. Dramatic Variability in High-ionization Broad Emission Lines

The Astrophysical Journal Supplement Series
We present a systematic search for changing-look (CL) quasars at high redshift z  > 0.9 by crossmatching the spectroscopic data sets from the Dark Energy Spectroscopic Instrument Data Release 1 and Sloan Digital Sky Survey Data Release 18. We identify 97
Zhi-Qiang Chen, Jun-Jie Jin, Wei-Jian Guo, Sheng-Xiu Sun, Zhi-Wei Pan, Chen-Xu Liu, Hua-Qing Cheng, Jing-Wei Hu, Zhen-Feng Sheng, Hu Zou, Zhao-Bin Chen, Qi Zheng, Qi-Rong Yuan   +12 more
doaj   +1 more source