Evidence for Merger Remnants in Early‐Type Host Galaxies of Low‐Redshift QSOs1

Bennert, Nicola; Canalizo, Gabriela; Jungwiert, Bruno; Stockton, Alan; Schweizer, F.; Peng, Chien Y.; Lacy, Mark

doi:10.1086/529068

Cited by 167 publications

(227 citation statements)

References 85 publications

(159 reference statements)

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“…Canalizo et al (2007) and Bennert et al (2008) estimate that the contribution of light in fine structure (disturbance features) for luminous quasars is between 6 and 13%. Similarly, we find that the PSQ disturbance features account for 3-28% of the total light with a mean of ∼10%.…”

Section: Morphologymentioning

confidence: 99%

Post-starburst quasars: bridging the gap between post-starburst galaxies and quasars

Cales

Brotherton

2015

Monthly Notices of the Royal Astronomical Society

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In order to better understand the nature of post-starburst quasars (PSQs) in the context of galaxy evolution, we compare their properties to those of post-starburst galaxies and quasars from appropriately selected samples possessing similar redshift (z ∼ 0.3), luminosity (M r ∼ −23), and data quality. We consider morphologies, spectral features, and derived physical properties of the stellar populations and central supermassive black hole. PSQs themselves come in two types: the more luminous AGNs with more luminous post-starburst stellar populations hosted by elliptical galaxies, some which are clearly merger products, and the less luminous systems existing within relatively undisturbed spiral galaxies and possessing signs of a more extended period of star formation. Post-starburst galaxies (PSQs) have elliptical and disturbed/postmerger morphologies similar to those of the more luminous PSQs, display similar spectral properties, but also can have younger stellar populations for a given starburst mass. Quasars at similar redshifts and luminosities around the Seyfert/quasar transition possess similar AGN characteristics, in terms of black hole mass and accretion rate, compared with those of PSQs, but do not appear to be hosted by galaxies with significant post-starburst populations. Recent studies of more luminous quasars find hosts consistent with those of our luminous PSQs, suggesting that these PSQs may be in transition between post-starburst galaxies and a more luminous quasar stage when the post-starburst stellar population remains dominant. The lower luminosity PSQs appear to differ from lower luminosity quasars (Seyfert galaxies) in terms of more significant star formation in their past.

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Section: Morphologymentioning

confidence: 99%

Post-starburst quasars: bridging the gap between post-starburst galaxies and quasars

Cales

Brotherton

2015

Monthly Notices of the Royal Astronomical Society

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“…Star formation (SF) in QSO host galaxies has been extensively studied using high-resolution imaging in the optical (e.g., Bahcall et al 1997;Dunlop et al 2003;Jahnke et al 2004) and near-infared (e.g., Kukula et al 2001;Guyon et al 2006;Veilleux et al 2009); emission line tracers such as the [O II] line (Hes et al 1993;Ho 2005;Silverman et al 2009;Kalfountzou et al 2012); mid-infrared emission lines and PAH features (Netzer et al 2007;Lutz et al 2008;Shi et al 2009); and farinfrared (FIR) and sub-mm photometry (e.g., Priddey et al 2003;Omont et al 2003;Lutz et al 2010;Serjeant & Hatziminaoglou 2009;Serjeant et al 2010;Bonfield et al 2011). In general, QSO hosts are in massive, spheroidally-dominated galaxies, which frequently show signs of on-going star-formation (e.g., Jahnke et al 2004;Trump et al 2013), though signatures of early stage mergers or strong disturbances are not particularly frequent (Dunlop et al 2003;Guyon et al 2006;Bennert et al 2008;Veilleux et al 2009). Very powerful starbursts are known to exist among high redshift QSOs, with ∼30% of very optically luminous systems showing star formation rates (SFRs) at the level of thousands of M /yr at z ∼ 2 (e.g., Omont et al 2003;Wang et al 2008).…”

Section: Introductionmentioning

confidence: 99%

The mean star-forming properties of QSO host galaxies

Rosario

Trakhtenbrot

Lutz

et al. 2013

A&A

126

112

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Quasi-stellar objects (QSOs) occur in galaxies in which supermassive black holes (SMBHs) are growing substantially through rapid accretion of gas. Many popular models of the co-evolutionary growth of galaxies and black holes predict that QSOs are also sites of substantial recent star formation (SF), mediated by important processes, such as major mergers, which rapidly transform the nature of galaxies. A detailed study of the star-forming properties of QSOs is a critical test of these models. We present a far-infrared Herschel/PACS study of the mean star formation rate (SFR) of a sample of spectroscopically observed QSOs to z ∼ 2 from the COSMOS extragalactic survey. This is the largest sample to date of moderately luminous QSOs (with nuclear luminosities that lie around the knee of the luminosity function) studied using uniform, deep far-infrared photometry. We study trends of the mean SFR with redshift, black hole mass, nuclear bolometric luminosity, and specific accretion rate (Eddington ratio). To minimize systematics, we have undertaken a uniform determination of SMBH properties, as well as an analysis of important selection effects of spectroscopic QSO samples that influence the interpretation of SFR trends. We find that the mean SFRs of these QSOs are consistent with those of normal massive star-forming galaxies with a fixed scaling between SMBH and galaxy mass at all redshifts. No strong enhancement in SFR is found even among the most rapidly accreting systems, at odds with several co-evolutionary models. Finally, we consider the qualitative effects on mean SFR trends from different assumptions about the SF properties of QSO hosts and from redshift evolution of the SMBH-galaxy relationship. While currently limited by uncertainties, valuable constraints on AGN-galaxy co-evolution can emerge from our approach.

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“…And indeed, gas-rich galaxy mergers are observed to fuel at least a substantial fraction of bright quasars (see e.g. Guyon et al 2006;Dasyra et al 2007;Silverman et al 2008;Bennert et al 2008;Liu et al 2009;Veilleux et al 2009;Letawe et al 2010;Koss et al 2010Koss et al , 2012, and references therein). Such encounters also convert disks into spheroids and further grow the bulge via centrally concentrated gas inflows in a merger-induced starburst (Mihos & Hernquist 1994;Hibbard & Yun 1999;Robertson et al 2006b; Naab * E-mail:phopkins@caltech.edu Cox et al 2006;Hopkins et al 2008aHopkins et al ,b, 2009a.…”

Section: Introductionmentioning

confidence: 99%

Do we expect most AGN to live in discs?

Hopkins¹,

Kocevski²,

Bundy³

2014

Monthly Notices of the Royal Astronomical Society

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Recent observations have indicated that a large fraction of the low to intermediate luminosity AGN population lives in disk-dominated hosts, while the more luminous quasars live in bulge-dominated hosts (that may or may not be major merger remnants), in conflict with some previous model predictions. We therefore build and compare a semi-empirical model for AGN fueling which accounts for both merger and non-merger "triggering." In particular, we show that the "stochastic accretion" model -in which fueling in disk galaxies is essentially a random process arising whenever dense gas clouds reach the nucleusprovides a good match to the present observations at low/intermediate luminosities. However it falls short of the high-luminosity population. We combine this with models for major merger-induced AGN fueling, which lead to rarer but more luminous events, and predict the resulting abundance of disk-dominated and bulge-dominated AGN host galaxies as a function of luminosity and redshift. We compile and compare observational constraints from z ∼ 0 − 2. The models and observations generically show a transition from disk to bulge dominance in hosts near the Seyfert-quasar transition, at all redshifts. "Stochastic" fueling dominates AGN by number (dominant at low luminosity), and dominates BH growth below the "knee" in the present-day BH mass function ( 10 7 M ). However it accounts for just ∼ 10% of BH mass growth at masses 10 8 M . In total, fueling in disky hosts accounts for ∼ 30% of the total AGN luminosity density/BH mass density. The combined model also accurately predicts the AGN luminosity function and clustering/bias as a function of luminosity and redshift; however, we argue that these are not sensitive probes of BH fueling mechanisms.

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Evidence for Merger Remnants in Early‐Type Host Galaxies of Low‐Redshift QSOs1

Cited by 167 publications

References 85 publications

Post-starburst quasars: bridging the gap between post-starburst galaxies and quasars

Post-starburst quasars: bridging the gap between post-starburst galaxies and quasars

The mean star-forming properties of QSO host galaxies

Do we expect most AGN to live in discs?

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