Major mergers host the most-luminous red quasars at z ∼ 2: A Hubble Space Telescope WFC3/IR study
- Department of Physics, Middlebury College, Middlebury, VT 05753 (United States)
- Oxford Astrophysics, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom)
- Institute for Astronomy, Department of Physics, ETH Zurich, Wolfgang-Pauli-Strasse 27, CH-8093 Zurich (Switzerland)
- Department of Physics and Yale Center for Astronomy and Astrophysics, Yale University, P.O. Box 208121, New Haven, CT 06520-8121 (United States)
- National Radio Astronomy Observatory, Charlottesville, VA (United States)
We used the Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) near-infrared camera to image the host galaxies of a sample of 11 luminous, dust-reddened quasars at z∼2—the peak epoch of black hole growth and star formation in the universe—to test the merger-driven picture for the coevolution of galaxies and their nuclear black holes. The red quasars come from the FIRST+2MASS red quasar survey and a newer, deeper, UKIDSS+FIRST sample. These dust-reddened quasars are the most intrinsically luminous quasars in the universe at all redshifts, and they may represent the dust-clearing transitional phase in the merger-driven black hole growth scenario. Probing the host galaxies in rest-frame visible light, the HST images reveal that 8/10 of these quasars have actively merging hosts, whereas one source is reddened by an intervening lower-redshift galaxy along the line of sight. We study the morphological properties of the quasar hosts using parametric Sérsic fits, as well as nonparametric estimators (Gini coefficient, M{sub 20}, and asymmetry). Their properties are heterogeneous but broadly consistent with the most extreme morphologies of local merging systems such as ultraluminous infrared galaxies. The red quasars have a luminosity range of log(L{sub bol})=47.8−48.3 (erg s{sup −1}), and the merger fraction of their hosts is consistent with merger-driven models of luminous active galactic nuclei activity at z = 2, which supports the picture in which luminous quasars and galaxies coevolve through major mergers that trigger both star formation and black hole growth.
- OSTI ID:
- 22883030
- Journal Information:
- Astrophysical Journal, Vol. 806, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Since 2009, the country of publication for this journal is the UK.; ISSN 0004-637X
- Country of Publication:
- United Kingdom
- Language:
- English
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