Results 21 to 30 of about 17,110 (224)

Target Selection and Validation of DESI Quasars

The Astrophysical Journal, 2023
The Dark Energy Spectroscopic Instrument (DESI) survey will measure large-scale structures using quasars as direct tracers of dark matter in the redshift range 0.9 < z < 2.1 and using Ly α forests in quasar spectra at z > 2.1.
Edmond Chaussidon, Christophe Yèche, Nathalie Palanque-Delabrouille, David M. Alexander, Jinyi Yang, Steven Ahlen, Stephen Bailey, David Brooks, Zheng Cai, Solène Chabanier, Tamara M. Davis, Kyle Dawson, Axel de laMacorra, Arjun Dey, Biprateep Dey, Sarah Eftekharzadeh, Daniel J. Eisenstein, Kevin Fanning, Andreu Font-Ribera, Enrique Gaztañaga, Satya Gontcho A Gontcho, Alma X. Gonzalez-Morales, Julien Guy, Hiram K. Herrera-Alcantar, Klaus Honscheid, Mustapha Ishak, Linhua Jiang, Stephanie Juneau, Robert Kehoe, Theodore Kisner, Andras Kovács, Anthony Kremin, Ting-Wen Lan, Martin Landriau, Laurent Le Guillou, Michael E. Levi, Christophe Magneville, Paul Martini, Aaron M. Meisner, John Moustakas, Andrea Muñoz-Gutiérrez, Adam D. Myers, Jeffrey A. Newman, Jundan Nie, Will J. Percival, Claire Poppett, Francisco Prada, Anand Raichoor, Corentin Ravoux, Ashley J. Ross, Edward Schlafly, David Schlegel, Ting Tan, Gregory Tarlé, Rongpu Zhou, Zhimin Zhou, Hu Zou   +56 more
doaj   +1 more source

Do Quasars Lens Quasars? [PDF]

The Astrophysical Journal, 1997
If the unexpectedly high frequency of quasar pairs with very different component redshifts is due to the lensing of a population of background quasars by the foreground quasar, typical lens masses must be $\sim10^{12}M_{\sun}$ and the sum of all such quasar lenses would have to contain $\sim0.005$ times the closure density of the Universe.
openaire   +2 more sources

Modelling accretion disk winds in quasars

, 2014
Outflows are ubiquitous in active galactic nuclei (AGN). They can take the form of either dramatic radio jets, which extend vast distances into the inter-galactic medium, or of much smaller scale winds - whose existence can be inferred only indirectly ...
Nick Higginbottom, Higginbottom, Nicholas   +1 more
core   +2 more sources

Highly accreting quasars at high redshift [PDF]

, 2017
The first results of a spectroscopic analysis for a sample of type I highly accreting quasars (L/LEdd ~ 1) at redshift z~2-3 observed with the OSIRIS spectrograph on the GTC 10.4 m ...
Marziani, Paola, Negrete, Alenka, C., Martínez-Aldama, Mary Loli, Sulentic, Jack, Dultzin, Deborah, Negrete, Alenka C., Del Olmo, Ascensión, Negrete, Alenka C. (5202820), Martínez-Aldama, Mary Loli (5202817), Sulentic, Jack (5202814), Marziani, Paola (5202811), Dultzin, Deborah (5202823), Del Olmo, Ascensión (5202826)   +12 more
core   +1 more source

Subaru High-z Exploration of Low-luminosity Quasars (SHELLQs). XVIII. The Dark Matter Halo Mass of Quasars at z ∼ 6

The Astrophysical Journal, 2023
We present, for the first time, dark matter halo (DMH) mass measurement of quasars at z ∼ 6 based on a clustering analysis of 107 quasars. Spectroscopically identified quasars are homogeneously extracted from the Hyper Suprime-Cam Strategic Survey ...
Junya Arita, Nobunari Kashikawa, Yoshiki Matsuoka, Wanqiu He, Kei Ito, Yongming Liang, Rikako Ishimoto, Takehiro Yoshioka, Yoshihiro Takeda, Kazushi Iwasawa, Masafusa Onoue, Yoshiki Toba, Masatoshi Imanishi   +12 more
doaj   +1 more source

Quasars as Cosmological Standard Candles [PDF]

, 2017
We propose the use of quasars with accretion rate near the Eddington ratio (extreme quasars) as standard candles. The selection criteria are based on the Eigenvector 1 (E1) formalism. Our first sample is a selection of 334 optical quasar spectra from the
Martínez-Aldama, Mary L., C. Alenka Negrete, Negrete, Alenka, Sulentic, Jack W., Sulentic, Jack, Ascensión Del Olmo, Esparza, Donají, Jack W. Sulentic, Donají Esparza-Arredondo, Mary L. Martínez-Aldama, Dultzin, Deborah, Martinez-Aldama, Mary Loli, Esparza-Arredondo, Donají, Del Olmo, Ascensión, Negrete, C. Alenka, MARZIANI, Paola, Deborah Dultzin, Paola Marziani   +17 more
core   +1 more source

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

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, Jason Dexter, W. N. Brandt, Luis C. Ho, Y. Homayouni, Donald P. Schneider, Yue Shen, Jonathan R. Trump   +7 more
doaj   +1 more source

Some Constraints on Quasar Progenitors and Quasar Evolution [PDF]

Symposium - International Astronomical Union, 1986
There is strong evidence that quasars are powered by the gravitational energy released by in fall of matter into a compact supermassive object which is most likely a black hole with mass M>106 to 109MO. The question then arises as to how such massive black holes came to be formed. What sort of objects were the progenitors?
openaire   +1 more source

The relative growth of optical and radio quasars in SDSS [PDF]

, 2010
We cross-correlate the Sloan Digital Sky Survey Data Release 3 quasar sample with Faint Images of the Radio Sky at Twenty centimetres (FIRST) and the Vestergaard et al.
Shankar, Francesco, Sivakoff, Gregory Robert, Vestergaard, Marianne, Dai, Xinyu   +3 more
core   +1 more source

Exploring galaxy mass profiles in strongly lensed quasars with upcoming Roman Space Telescope observations [PDF]

EPJ Web of Conferences
Strong gravitational lensing of quasars is a powerful tool for probing cosmological parameters, tracing galaxy evolution, and investigating the internal structure of quasars.
Guliqani Esmeralda, Hamolli Lindita, Hafizi Mimoza   +2 more
doaj   +1 more source