Close companions to two high-redshift quasars

Ian D. McGreer, Xiaohui Fan, Michael A. Strauss, Zoltàn Haiman, Gordon T. Richards, Linhua Jiang, Fuyan Bian, Donald P. Schneider

Research output: Contribution to journalArticle

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Abstract

We report the serendipitous discoveries of companion galaxies to two high-redshift quasars. SDSS J025617.7+001904 is a z = 4.79 quasar included in our recent survey of faint quasars in the SDSS Stripe 82 region. The initial MMT slit spectroscopy shows excess Lyα emission extending well beyond the quasar's light profile. Further imaging and spectroscopy with LBT/MODS1 confirms the presence of a bright galaxy (i AB= 23.6) located 2″ (12 kpc projected) from the quasar with strong Lyα emission (EW0≈ 100 A˚) at the redshift of the quasar, as well as faint continuum. The second quasar, CFHQS J005006.6+344522 (z = 6.25), is included in our recent HST SNAP survey of z ∼ 6 quasars searching for evidence of gravitational lensing. Deep imaging with ACS and WFC3 confirms an optical dropout ∼4.5 mag fainter than the quasar (YAB= 25) at a separation of 0.″9. The red i775- Y105 color of the galaxy and its proximity to the quasar (5 kpc projected if at the quasar redshift) strongly favor an association with the quasar. Although it is much fainter than the quasar, it is remarkably bright when compared to field galaxies at this redshift, while showing no evidence for lensing. Both systems may represent late-stage mergers of two massive galaxies, with the observed light for one dominated by powerful ongoing star formation and for the other by rapid black hole growth. Observations of close companions are rare; if major mergers are primarily responsible for high-redshift quasar fueling then the phase when progenitor galaxies can be observed as bright companions is relatively short.

Original languageEnglish (US)
Article number73
JournalAstronomical Journal
Volume148
Issue number4
DOIs
StatePublished - Oct 1 2014

Fingerprint

merger
quasars
spectroscopy
galaxies
SNAP
dropouts
refueling
slits
proximity
star formation
continuums
color

Keywords

  • galaxies: high-redshift
  • quasars: general
  • quasars: individual (SDSS J025617.7+001904, CFHQSJ005006.6+344522)

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

McGreer, I. D., Fan, X., Strauss, M. A., Haiman, Z., Richards, G. T., Jiang, L., ... Schneider, D. P. (2014). Close companions to two high-redshift quasars. Astronomical Journal, 148(4), [73]. https://doi.org/10.1088/0004-6256/148/4/73

Close companions to two high-redshift quasars. / McGreer, Ian D.; Fan, Xiaohui; Strauss, Michael A.; Haiman, Zoltàn; Richards, Gordon T.; Jiang, Linhua; Bian, Fuyan; Schneider, Donald P.

In: Astronomical Journal, Vol. 148, No. 4, 73, 01.10.2014.

Research output: Contribution to journalArticle

McGreer, ID, Fan, X, Strauss, MA, Haiman, Z, Richards, GT, Jiang, L, Bian, F & Schneider, DP 2014, 'Close companions to two high-redshift quasars', Astronomical Journal, vol. 148, no. 4, 73. https://doi.org/10.1088/0004-6256/148/4/73
McGreer ID, Fan X, Strauss MA, Haiman Z, Richards GT, Jiang L et al. Close companions to two high-redshift quasars. Astronomical Journal. 2014 Oct 1;148(4). 73. https://doi.org/10.1088/0004-6256/148/4/73
McGreer, Ian D. ; Fan, Xiaohui ; Strauss, Michael A. ; Haiman, Zoltàn ; Richards, Gordon T. ; Jiang, Linhua ; Bian, Fuyan ; Schneider, Donald P. / Close companions to two high-redshift quasars. In: Astronomical Journal. 2014 ; Vol. 148, No. 4.
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