Host galaxies of z = 4 quasars

K. K. McLeod, Jill Bechtold

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

We have undertaken a project to investigate the host galaxies and environments of a sample of quasars at z 4. In this paper, we describe deep near-infrared imaging of 34 targets using the Magellan I and Gemini North telescopes. We discuss in detail special challenges of distortion and nonlinearity that must be addressed when performing point-spread function (PSF) subtraction with data from these telescopes and their IR cameras, especially in very good seeing. We derive black hole masses from emission-line spectroscopy, and we calculate accretion rates from our Ks -band photometry, which directly samples the rest frame B for these objects. We introduce a new isophotal diameter technique for estimating host galaxy luminosities. We report the detection of four host galaxies on our deepest, sharpest images, and present upper limits for the others. We find that if host galaxies passively evolve such that they brighten by 2 mag or more in the rest-frame B band between the present and z = 4, then high-z hosts are less massive at a given black hole mass than are their low-z counterparts. We argue that the most massive hosts plateau at ≲10 L*. We estimate the importance of selection effects on this survey and the subsequent limitations of our conclusions. These results are in broad agreement with recent semianalytical models for the formation of luminous quasars and their host spheroids by mergers of gas-rich galaxies, with significant dissipation, and self-regulation of black hole growth and star formation by the burst of merger-induced quasar activity.

Original languageEnglish (US)
Pages (from-to)415-438
Number of pages24
JournalAstrophysical Journal
Volume704
Issue number1
DOIs
StatePublished - 2009

Fingerprint

quasars
galaxies
merger
nonlinearity
telescopes
dissipation
near infrared
spectroscopy
accretion
plateau
spheroids
point spread functions
subtraction
photometry
star formation
plateaus
bursts
gas
estimating
cameras

Keywords

  • Galaxies: evolution
  • Galaxies: high-redshift
  • Quasars: general

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Host galaxies of z = 4 quasars. / McLeod, K. K.; Bechtold, Jill.

In: Astrophysical Journal, Vol. 704, No. 1, 2009, p. 415-438.

Research output: Contribution to journalArticle

McLeod, K. K. ; Bechtold, Jill. / Host galaxies of z = 4 quasars. In: Astrophysical Journal. 2009 ; Vol. 704, No. 1. pp. 415-438.
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