Results 11 to 20 of about 2,405 (218)

New Constraints on Quasar Broad Absorption and Emission Line Regions from Gravitational Microlensing [PDF]

Frontiers in Astronomy and Space Sciences, 2017
Gravitational microlensing is a powerful tool allowing one to probe the structure of quasars on sub-parsec scale. We report recent results, focusing on the broad absorption and emission line regions.
Damien Hutsemékers, Lorraine Braibant, Dominique Sluse, Timo Anguita, René Goosmann   +4 more
doaj   +3 more sources

Extreme Variability in a Broad Absorption Line Quasar [PDF]

The Astrophysical Journal, 2017
Abstract CRTS J084133.15+200525.8 is an optically bright quasar at z = 2.345 that has shown extreme spectral variability over the past decade. Photometrically, the source had a visual magnitude of V ∼ 17.3 between 2002 and 2008. Then, over the following five years, the source slowly brightened by approximately one magnitude, to V ∼ 16.2.
Daniel Stern, Matthew J. Graham, Nahum Arav, S. G. Djorgovski, Carter Chamberlain, Aaron J. Barth, Ciro Donalek, Andrew J. Drake, Eilat Glikman, Hyunsung D. Jun, Ashish A. Mahabal, Charles. C. Steidel   +11 more
openaire   +5 more sources

Variability in Quasar Broad Absorption Line Outflows [PDF]

Proceedings of the International Astronomical Union, 2009
Broad absorption lines (BALs) in quasar spectra identify high-velocity outflows that likely exist in all quasars and could play a major role in feedback to galaxy evolution (e.g., Di Matteo et al. 2005). Studying the variability in these BALs can help us understand the structure, evolution, and basic physical properties of these outflows.
Daniel M. Capellupo, Fred Hamann, Joseph C. Shields, Tom A. Barlow, Paola Rodriguez   +4 more
openaire   +2 more sources

Gemini Near Infrared Spectrograph−Distant Quasar Survey: Rest-frame Ultraviolet−Optical Spectral Properties of Broad Absorption Line Quasars [PDF]

The Astrophysical Journal
We present the rest-frame ultraviolet−optical spectral properties of 65 broad absorption line (BAL) quasars from the Gemini Near Infrared Spectrograph−Distant Quasar Survey (GNIRS-DQS). These properties are compared with those of 195 non-BAL quasars from
Harum Ahmed, Ohad Shemmer, Brandon Matthews, Cooper Dix, Trung Ha, Gordon T. Richards, Michael S. Brotherton, Adam D. Myers, W. N. Brandt, Sarah C. Gallagher, Richard Green, Paulina Lira, Jacob N. McLane, Richard M. Plotkin, Donald P. Schneider   +14 more
doaj   +2 more sources

Balmer Absorption in Iron Low-ionization Broad Absorption Line Quasars [PDF]

The Astrophysical Journal
While C iv is the most common absorption line in broad absorption line quasar spectra, Balmer absorption lines (BALs) are among the rarest. We present analysis of Balmer absorption in a sample of 14 iron low-ionization BAL quasars (FeLoBALQs); eight are ...
Karen M. Leighly, Sarah C. Gallagher, Hyunseop Choi, Donald M. Terndrup, Julianna R. Voelker, Gordon T. Richards, Leah K. Morabito   +6 more
doaj   +2 more sources

The Discovery of a Luminous Broad Absorption Line Quasar at a Redshift of 7.02 [PDF]

The Astrophysical Journal Letters, 2018
Abstract Despite extensive efforts, to date only two quasars have been found at z > 7, due to a combination of low spatial density and high contamination from more ubiquitous Galactic cool dwarfs in quasar selection. This limits our current knowledge of the super-massive black hole growth mechanism and reionization history.
Feige Wang, Jinyi Yang, Xiaohui Fan, Minghao Yue, Xue-Bing Wu, Jan-Torge Schindler, Fuyan Bian, Jiang-Tao Li, Emanuele P. Farina, Eduardo Bañados, Frederick B. Davies, Roberto Decarli, Richard Green, Linhua Jiang, Joseph F. Hennawi, Yun-Hsin Huang, Chiara Mazzucchelli, Ian D. McGreer, Bram Venemans, Fabian Walter, Yuri Beletsky   +20 more
openaire   +6 more sources

Appearance versus disappearance of broad absorption line troughs in quasars [PDF]

Monthly Notices of the Royal Astronomical Society, 2021
ABSTRACT We present a new set of 84 broad absorption line (BAL) quasars (1.7 < zem < 4.4) exhibiting an appearance of C iv BAL troughs over 0.3–4.8 rest-frame years by comparing the Sloan Digital Sky Survey Data Release (SDSSDR)-7, SDSSDR-12, and SDSSDR-14 quasar catalogues. We contrast the nature of BAL variability in this
Mishra, Sapna, Vivek, M., Chand, Hum, Joshi, Ravi   +3 more
openaire   +2 more sources

Submillimeter Observations of a Sample of Broad Absorption Line Quasars [PDF]

The Astrophysical Journal, 2003
The broad absorption line (BAL) features seen in a small fraction of quasar optical/UV spectra are attributed to bulk outflows away from the quasar core. Observational evidence suggests that dust plays a key role in these systems, although whether the inferred dust properties are a signature of orientation effects or whether they are indicative of an ...
Lewis, Geraint F., Chapman, Scott C., Kuncic, Zdenka   +2 more
openaire   +2 more sources

Emergence and Variability of Broad Absorption Line Quasar Outflows [PDF]

The Astrophysical Journal, 2018
Abstract We isolate a set of quasars that exhibit emergent C iv broad absorption lines (BALs) in their spectra by comparing spectra in the Sloan Digital Sky Survey (SDSS) Data Release 7 and the SDSS/BOSS Data Releases 9 and 10. After visually defining a set of emergent BALs, follow-up observations were obtained with the Gemini ...
J. A. Rogerson, P. B. Hall, N. S. Ahmed, P. Rodríguez Hidalgo, W. N. Brandt, N. Filiz Ak   +5 more
openaire   +4 more sources

Broad absorption line variability in radio-loud quasars [PDF]

Monthly Notices of the Royal Astronomical Society, 2014
We investigate C IV broad absorption line (BAL) variability within a sample of 46 radio-loud quasars (RLQs), selected from SDSS/FIRST data to include both core-dominated (39) and lobe-dominated (7) objects. The sample consists primarily of high-ionization BAL quasars, and a substantial fraction have large BAL velocities or equivalent widths; their ...
Welling, C. A., Miller, B. P., Brandt, W. N., Capellupo, D. M., Gibson, R. R.   +4 more
openaire   +2 more sources