HOST GALAXIES OF LUMINOUS TYPE 2 QUASARS AT z {approx} 0.5

Journal Article · Thu Sep 10 04:00:00 EDT 2009 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/702/2/1098; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21336048

Xin, Liu; Greene, Jenny E; Strauss, Michael A ^[1]; Zakamska, Nadia L ^[2]; Krolik, Julian H; Heckman, Timothy M ^[3]

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1. Department of Astrophysical Sciences, Princeton University, Peyton Hall, Ivy Lane, Princeton, NJ 08544 (United States)
2. Institute for Advanced Study, Einstein Dr., Princeton, NJ 08540 (United States)
3. Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States)

We present deep Gemini GMOS optical spectroscopy of nine luminous quasars at redshifts z {approx} 0.5, drawn from the Sloan Digital Sky Survey type 2 quasar sample. Our targets were selected to have high intrinsic luminosities (M{sub V} < -26 mag) as indicated by the [O III] {lambda}5007 A emission-line luminosity (L[{sub OIII}]). Our sample has a median black hole mass of {approx}10{sup 8.8} M{sub sun} inferred assuming the local M {sub BH}-{sigma}{sub *} relation and a median Eddington ratio of {approx}0.7, using stellar velocity dispersions {sigma}{sub *} measured from the G band. We estimate the contamination of the stellar continuum from scattered quasar light based on the strength of broad H{beta}, and provide an empirical calibration of the contamination as a function of L {sub [OIII]}; the scattered-light fraction is {approx}30% of L{sub 5100} for objects with L {sub [OIII]} = 10{sup 9.5} L{sub sun}. Population synthesis indicates that young poststarburst populations (<0.1 Gyr) are prevalent in luminous type 2 quasars, in addition to a relatively old population (>1 Gyr) which dominates the stellar mass. Broad emission complexes around He II {lambda}4686 A with luminosities up to 10{sup 8.3} L{sub sun} are unambiguously detected in three out of the nine targets, indicative of Wolf-Rayet (WR) populations. Population synthesis shows that {approx}5 Myr poststarburst populations contribute substantially to the luminosities (>50% of L{sub 5100}) of all three objects with WR detections. We find two objects with double cores and four with close companions. Our results may suggest that luminous type 2 quasars trace an early stage of galaxy interaction, perhaps responsible for both the quasar and the starburst activity.

• OSTI ID: 21336048
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 702; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
BLACK HOLES
CALIBRATION
EMISSION
GALACTIC EVOLUTION
GALAXIES
GALAXY NUCLEI
LUMINOSITY
QUASARS
RED SHIFT
SPECTROSCOPY
VISIBLE RADIATION