Star formation rates in luminous quasars at 2 < z < 3

Kathryn Harris, Duncan Farrah, Bernhard Schulz, Evanthia Hatziminaoglou, Marco Viero, Nick Anderson, Matthieu Béthermin, Scott Chapman, David L. Clements, Asantha Cooray, Andreas Efstathiou, Anne Feltre, Peter Hurley, Eduardo Ibar, Mark Lacy, Sebastian Oliver, Mathew J. Page, Ismael Pérez-Fournon, Sara M. Petty, Lura K. PitchfordDimitra Rigopoulou, Douglas Scott, Myrto Symeonidis, Joaquin Vieira, Lingyu Wang

Research output: Contribution to journalArticlepeer-review

Abstract

We investigate the relation between star formation rates (M˙s) and AGN properties in optically selected type 1 quasars at 2 < z < 3 using data from Herschel and the SDSS. We find that M˙s remains approximately constant with redshift, at 300 ± 100M yr-1. Conversely, M˙s increases with AGN luminosity, up to a maximum of ~600M yr-1, and with CIV FWHM. In context with previous results, this is consistent with a relation between M˙s and black hole accretion rate (M˙bh) existing in only parts of the z - M˙s - M˙bh plane, dependent on the free gas fraction, the trigger for activity, and the processes that may quench star formation. The relations between M˙s and both AGN luminosity and C IV FWHM are consistent with star formation rates in quasars scaling with black hole mass, though we cannot rule out a separate relation with black hole accretion rate. Star formation rates are observed to decline with increasing CIV equivalent width. This decline can be partially explained via the Baldwin effect, but may have an additional contribution from one or more of three factors; Mi is not a linear tracer of L2500, the Baldwin effect changes form at high AGN luminosities, and high C IV EW values signpost a change in the relation between M˙s and M˙bh. Finally, there is no strong relation between M˙s and Eddington ratio, or the asymmetry of the C IV line. The former suggests that star formation rates do not scale with how efficiently the black hole is accreting, while the latter is consistent with C IV asymmetries arising from orientation effects.

Original languageEnglish (US)
Pages (from-to)4179-4194
Number of pages16
JournalMonthly Notices of the Royal Astronomical Society
Volume457
Issue number4
DOIs
StatePublished - Feb 10 2016

Keywords

  • Galaxies: evolution
  • Galaxies: star formation
  • Galaxies: starburst
  • Infrared: galaxies
  • Quasars: general

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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