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We present near-IR, low resolution spectra of eight of the most distant quasars known, with redshifts in the range 4.9<z<6.4. Half of these quasars are characterized by deep, broad and blueshifted absorption features associated with both…

Astrophysics · Physics 2009-11-10 R. Maiolino , E. Oliva , F. Ghinassi , M. Pedani , F. Mannucci , R. Mujica , Y. Juarez

At low redshifts, dust-obscured quasars often have strong yet narrow permitted lines in the rest-frame optical and ultraviolet, excited by the central active nucleus, earning the designation Type II quasars. We present a sample of 145…

We present the first discovery of dust-reddened quasars (red quasars) in the high-z universe (z >5.6). This is a result from the Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs) project, which is based on the sensitive…

We have analysed a sample of 25 extremely red H-[4.5]>4 galaxies, selected using 4.5 micron data from the Spitzer SEDS survey and deep H-band data from the Hubble Space Telescope (HST) CANDELS survey, over ~180 square arcmin of the UKIDSS…

We use the deep NIR imaging of the FIRES survey to investigate trends with redshift of the properties of galaxies selected to have strong Balmer/4000A breaks at 2<z<4.5. Analagous to the J-K>1.3 (AB) color criterion designed to select red…

Astrophysics · Physics 2009-11-11 Gabriel B. Brammer , Pieter G. van Dokkum

The Chandra Deep Field South (CDF-S) 1Ms exposure produced a catalog of 346 X-ray sources, of which 59 were not visible on the VLT/FORS1 and the ESO-MPI/WFI deep R-band images to a limit of R_{vega}=26.1--26.7 mag. Using the first release…

We report the results of near-infrared spectroscopic observations of 37 quasars in the redshift range $6.3< z\le7.64$, including 32 quasars at $z>6.5$, forming the largest quasar near-infrared spectral sample at this redshift. The spectra,…

We present observed mid-infrared and optical colors and composite spectral energy distributions (SEDs) of type 1 (broad-line) and 2 (narrow-line) quasars selected from Sloan Digital Sky Survey (SDSS) spectroscopy. A significant fraction of…

Astrophysics of Galaxies · Physics 2017-11-08 Ryan C. Hickox , Adam D. Myers , Jenny E. Greene , Kevin N. Hainline , Nadia L. Zakamska , Michael A. DiPompeo

We present new data on several z=1.54 radio-loud quasar fields from a sample of 31 at z=1-2 in which we have previously identified an excess population of predominantly red galaxies. Narrow-band H-alpha observations detect five candidate…

Astrophysics · Physics 2007-05-23 Patrick Hall , Marcin Sawicki , C. J. Pritchet , F. D. A. Hartwick , Aaron Evans

The Parkes Half-Jansky Flat Spectrum Sample contains a large number of sources with unusually red optical-to-near-infrared continua. If this is to be interpreted as extinction by dust in the line-of-sight, then associated material might…

Astrophysics · Physics 2009-10-30 Frank J. Masci , Michael J. Drinkwater , Rachel L. Webster

We report the discovery of 27 quasars with redshifts between 3.58 and 4.49. The objects were identified as high-redshift candidates based on their colors in Sloan Digital Sky Survey commissioning data. The redshifts were confirmed with low…

We investigate the luminosity and redshift dependence of the quasar continuum by means of composite spectrum using a large non-BAL radio-quiet quasar sample drawn from the Sloan Digital Sky Survey. Quasar continuum slopes in the UV-Opt band…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-24 Xiaoyi Xie , Shiyin Shen , Zhengyi Shao , Jun Yin

The detection of powerful near-infrared emission in high redshift (z>5) quasars demonstrates that very hot dust is present close to the active nucleus also in the very early universe. A number of high-redshift objects even show significant…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 C. Leipski , K. Meisenheimer

We present, for the first time, a systematic study of quasar-associated 2175 \AA\ dust absorbers using spectroscopic data from the Sloan Digital Sky Survey (SDSS) Data Release 16 (DR16). By analyzing the optical spectra and multi-band…

Astrophysics of Galaxies · Physics 2025-05-28 Shaohua Zhang , Yuchong Luo , Shangchun Xie , Chao Gao , Zhijian Luo , Chenggang Shu , Hubing Xiao

X-ray absorption of high-redshift quasars is enigmatic, because it remains unclear where in the universe the absorbing gas is. If absorption occurs near the high-z host, it could help us understand early stages of galaxy formation. If it is…

High Energy Astrophysical Phenomena · Physics 2019-09-25 Sivan Ben Haim , Ehud Behar , Richard F. Mushotzky

The goal of this work is to study the obscuration properties of mid-infrared (mid-IR) selected AGN. For that purpose, we use {\it{WISE}} sources in the Stripe 82-XMM area to identify mid-IR AGN candidates, applying the Assef et al.…

Astrophysics of Galaxies · Physics 2020-01-08 G. Mountrichas , I. Georgantopoulos , A. Ruiz , G. Kampylis

The goal of the Complete Optical and Radio Absorption Line System (CORALS) survey is to quantify the potential impact on QSO absorber statistics from dust in intervening galaxies. Dust may introduce a selection bias in surveys which are…

Astrophysics · Physics 2009-11-10 Sara L. Ellison , Chris W. Churchill , Samantha A. Rix , Max Pettini

We report observations of a sample of high redshift sources (1.8<z<4.7), mainly radio-quiet quasars, at 350 microns using the SHARC bolometer camera at the Caltech Submillimeter Observatory. Nine sources were detected (>4-sigma) and upper…

We have conducted ultra-deep optical and deep near-infrared observations of a field around the z=1.226 radio-quiet quasar 104420.8+055739 from the Clowes-Campusano LQG of 18 quasars at z~1.3 in search of associated galaxy clustering.…

Astrophysics · Physics 2015-06-24 C. P. Haines , R. G. Clowes , L. E. Campusano , A. J. Adamson

We present a highly complete sample of broad-line (Type 1) QSOs out to z ~ 3 selected by their mid-infrared colors, a method that is minimally affected by dust reddening. We remove host galaxy emission from the spectra and fit for excess…

Astrophysics of Galaxies · Physics 2022-08-17 E. Glikman , M. Lacy , S. LaMassa , C. Bradley , S. G. Djorgovski , T. Urrutia , E. L. Gates , M. J. Graham , C. M. Urry , I. Yoon