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Title: SDSS 0956+5128: A BROAD-LINE QUASAR WITH EXTREME VELOCITY OFFSETS

Abstract

We report on the discovery of a Type 1 quasar, SDSS 0956+5128, with a surprising combination of extreme velocity offsets. SDSS 0956+5128 is a broad-lined quasar exhibiting emission lines at three substantially different redshifts: a systemic redshift of z {approx} 0.714 based on narrow emission lines, a broad Mg II emission line centered 1200 km s{sup -1} bluer than the systemic velocity, at z {approx} 0.707, and broad H{alpha} and H{beta} emission lines centered at z {approx} 0.690. The Balmer line peaks are 4100 km s{sup -1} bluer than the systemic redshift. There are no previously known objects with such an extreme difference between broad Mg II and broad Balmer emission. The two most promising explanations are either an extreme disk emitter or a high-velocity black hole recoil. However, neither explanation appears able to explain all of the observed features of SDSS 0956+5128, so the object may provide a challenge to our general understanding of quasar physics.

Authors:
; ;  [1]; ; ;  [2];  [3]; ;  [4]; ;  [5]
  1. Kavli IPMU, University of Tokyo, Kashiwanoha 5-1-5, Kashiwa-shi, Chiba (Japan)
  2. Department of Astrophysical Sciences, Princeton University, Ivy Lane, Princeton, NJ 08544 (United States)
  3. California Institute of Technology, MC 249-17, 1200 East California Boulevard, Pasadena, CA 91125 (United States)
  4. Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States)
  5. Department of Physics and Astronomy, University of California, Riverside, CA 92508 (United States)
Publication Date:
OSTI Identifier:
22086492
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 759; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCRETION DISKS; ASTROPHYSICS; BALMER LINES; BLACK HOLES; COSMOLOGY; GALACTIC EVOLUTION; GALAXIES; GALAXY NUCLEI; MAGNESIUM IONS; PHOTON EMISSION; QUASARS; RECOILS; RED SHIFT; VELOCITY

Citation Formats

Steinhardt, Charles L., Schramm, Malte, Silverman, John D., Alexandroff, Rachael, Pattarakijwanich, Petchara, Strauss, Michael A., Capak, Peter, Civano, Francesca, Elvis, Martin, Masters, Dan, and Mobasher, Bahram. SDSS 0956+5128: A BROAD-LINE QUASAR WITH EXTREME VELOCITY OFFSETS. United States: N. p., 2012. Web. doi:10.1088/0004-637X/759/1/24.
Steinhardt, Charles L., Schramm, Malte, Silverman, John D., Alexandroff, Rachael, Pattarakijwanich, Petchara, Strauss, Michael A., Capak, Peter, Civano, Francesca, Elvis, Martin, Masters, Dan, & Mobasher, Bahram. SDSS 0956+5128: A BROAD-LINE QUASAR WITH EXTREME VELOCITY OFFSETS. United States. doi:10.1088/0004-637X/759/1/24.
Steinhardt, Charles L., Schramm, Malte, Silverman, John D., Alexandroff, Rachael, Pattarakijwanich, Petchara, Strauss, Michael A., Capak, Peter, Civano, Francesca, Elvis, Martin, Masters, Dan, and Mobasher, Bahram. Thu . "SDSS 0956+5128: A BROAD-LINE QUASAR WITH EXTREME VELOCITY OFFSETS". United States. doi:10.1088/0004-637X/759/1/24.
@article{osti_22086492,
title = {SDSS 0956+5128: A BROAD-LINE QUASAR WITH EXTREME VELOCITY OFFSETS},
author = {Steinhardt, Charles L. and Schramm, Malte and Silverman, John D. and Alexandroff, Rachael and Pattarakijwanich, Petchara and Strauss, Michael A. and Capak, Peter and Civano, Francesca and Elvis, Martin and Masters, Dan and Mobasher, Bahram},
abstractNote = {We report on the discovery of a Type 1 quasar, SDSS 0956+5128, with a surprising combination of extreme velocity offsets. SDSS 0956+5128 is a broad-lined quasar exhibiting emission lines at three substantially different redshifts: a systemic redshift of z {approx} 0.714 based on narrow emission lines, a broad Mg II emission line centered 1200 km s{sup -1} bluer than the systemic velocity, at z {approx} 0.707, and broad H{alpha} and H{beta} emission lines centered at z {approx} 0.690. The Balmer line peaks are 4100 km s{sup -1} bluer than the systemic redshift. There are no previously known objects with such an extreme difference between broad Mg II and broad Balmer emission. The two most promising explanations are either an extreme disk emitter or a high-velocity black hole recoil. However, neither explanation appears able to explain all of the observed features of SDSS 0956+5128, so the object may provide a challenge to our general understanding of quasar physics.},
doi = {10.1088/0004-637X/759/1/24},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 759,
place = {United States},
year = {2012},
month = {11}
}