Results 1 to 10 of about 116,814 (325)
Target Selection and Validation of DESI Quasars [PDF]
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 +56 more
doaj +2 more sources
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.
Boyle B. J. +6 more
openaire +5 more sources
A Sample of Quasars with Strong Nitrogen Emission Lines from the Sloan Digital Sky Survey [PDF]
Astrophys.J.679:962-966,2008, 2008 We report on 293 quasars with strong NIV] lambda 1486 or NIII] lambda 1750 emission lines (rest-frame equivalent width > 3 \AA) at 1.7 < z < 4.0 selected from the Sloan Digital Sky Survey (SDSS) Fifth Data Release. These nitrogen-rich (N-rich) objects comprise ~1.1% of the SDSS quasars.
Fan, Xiaohui +2 more
arxiv +5 more sources
Energy input from quasars regulates the growth and activity of black holes and their host galaxies [PDF]
Nature, 2005 In the early Universe, while galaxies were still forming, black holes as massive as a billion solar masses powered quasars. Supermassive black holes are found at the centres of most galaxies today, where their masses are related to the velocity ...
Tiziana Di Matteo +2 more
exaly +2 more sources
On the link between associated MgII absorbers and star formation in quasar hosts [PDF]
, 2011 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. These associated absorption line systems (AALs) are usually interpreted as absorbers that are either intrinsic to the quasar and its host, or arising from external galaxies clustering around the ...
Bahcall +22 more
arxiv +3 more sources
Discovery of spectacular quasar-driven superbubbles in red quasars. [PDF]
Sci Adv, 2023 Quasar-driven outflows on galactic scales are a routinely invoked ingredient for galaxy formation models. We report the discovery of ionized gas nebulae surrounding three luminous red quasars at z ~ 0.4 from Gemini integral field unit observations.
Shen L +9 more
europepmc +4 more sources
Predicting the Yields of z > 6.5 Quasar Surveys in the Era of Roman and Rubin [PDF]
The Astrophysical Journal, 2023 About 70 luminous quasars discovered at z > 6.5 are strongly biased toward the bright end, thus not providing a comprehensive view of quasar abundance beyond the cosmic dawn. We present the predicted results of the Roman/Rubin high-redshift quasar survey,
Wei Leong Tee +5 more
doaj +2 more sources
A slitless spectroscopic survey for quasars near quasars [PDF]
Astronomy & Astrophysics, 2008 18 pages, 16 figures, accepted by A&A, includes Table 2 from online material, full paper with appendices containing additional figures and tables available at http://www.aip.de/People/gworseck/qnqpaper/qnqpaper_final ...
Lutz Wisotzki +2 more
openaire +6 more sources
Extreme Quasars as Distance Indicators in Cosmology
Frontiers in Astronomy and Space Sciences, 2020 Quasars accreting matter at very high rates (known as extreme Population A [xA] quasars, possibly associated with super-Eddington accreting massive black holes) may provide a new class of distance indicators covering cosmic epochs from present day up to ...
Paola Marziani +2 more
exaly +3 more sources
A Main Sequence for Quasars [PDF]
Frontiers in Astronomy and Space Sciences, 2018 The last 25 years saw a major step forward in the analysis of optical and UV spectroscopic data of large quasar samples. Multivariate statistical approaches have led to the definition of systematic trends in observational properties that are the basis of
P. Marziani +9 more
semanticscholar +9 more sources