Radio-quiet quasar environments at 0.5 &lt;= z &lt;= 0.8

Wold, M.; Lacy, Mark; Lilje, P. B.; Serjeant, S.

doi:10.1046/j.1365-8711.2001.04229.x

Cited by 50 publications

(44 citation statements)

References 119 publications

(268 reference statements)

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“…There is an abundance of circumstantial evidence in the literature connecting QSO activity at low redshifts with mergers and interactions (e.g., Heckman et al 1984;Hutchings et al 1988;Canalizo & Stockton 2001;Urrutia et al 2008). Not only do a number of low-redshift QSOs show signs of interactions and mergers, but there is also a tendency for QSO host galaxies to exist in only moderately rich environments (e.g., Dressler et al 1985;Ellingson et al 1991;Wold et al 2001;see, however, Martini et al 2007 for a counterexample), consistent with the results of quasar clustering studies, which suggests that quasars exist in halos of mass $10 12 -10 13 M ( Hopkins et al 2007a;da Angela et al 2008). In such environments, velocity dispersions are moderate, and interactions have their greatest effect.…”

Section: Introductionmentioning

confidence: 99%

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

Bennert

Canalizo

Jungwiert

et al. 2008

ApJ

167

206

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We present results from a pilot HST ACS deep imaging study in broadband Vof five low-redshift QSO host galaxies classified in the literature as ellipticals. The aim of our study is to determine whether these early-type hosts formed at high redshift and have since evolved passively, or whether they have undergone relatively recent mergers that may be related to the triggering of the nuclear activity. We perform two-dimensional modeling of the light distributions to analyze the host galaxies' morphology. We find that, while each host galaxy is reasonably well fitted by a de Vaucouleurs profile, the majority of them (4/5) reveal significant fine structure such as shells and tidal tails. These structures contribute between $5% and 10% to the total V-band luminosity of each host galaxy within a region of r $ 3r eA and are indicative of merger events that occurred between a few hundred Myr and a Gyr ago. These timescales are comparable to starburst ages in the QSO hosts previously inferred from Keck spectroscopy. Our results thus support a consistent scenario in which most of the QSO host galaxies suffered mergers with accompanying starbursts that likely also triggered the QSO activity in some way, but we are also left with considerable uncertainty on physical mechanisms that might have delayed this triggering for several hundred Myr after the merger.

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Section: Introductionmentioning

confidence: 99%

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

Bennert

Canalizo

Jungwiert

et al. 2008

ApJ

167

206

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“…Radio galaxies, which are intimately connected with RLQs in unification models, also appear to reside in cluster environments at high redshift (Pentericci et al 2000). However, the dichotomy between radio-loud and radio-quiet properties is now being questioned by studies which have found that almost all QSO hosts are elliptical galaxies, regardless of radio-loudness (McLure et al 1999;Dunlop et al 2002), and that the environments of RLQs are statistically indistinguishable from those of RQQs, at least at z < ∼ 1 (Hutchings et al 1995;McLure & Dunlop 2001;Wold et al 2001;Finn et al 2001). At higher redshifts, there is evidence that galaxy density maybe higher around RLQs, although a milder overdensity is seen towards RQQs (see review by Hutchings 2001).…”

Section: Introductionmentioning

confidence: 99%

The CORALS survey

Ellison

Yan²,

Hook³

et al. 2002

A&A

121

160

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Abstract. We present a list of z abs ∼ zem (∆v < 3000 km s −1 ) DLAs discovered during the CORALS survey for absorbers in a radio-selected QSO sample. On the assumption that z abs ∼ zem DLAs are neither ejecta from the QSO, nor part of the host galaxy itself, we use the number density statistics of these DLAs to investigate galaxy clustering near the QSO redshift. We find that n(z) of z abs ∼ zem DLAs in our radio-selected QSO sample is ∼4 times larger than the number density of intervening DLAs, implying an excess of galaxies near the QSO. This result is further supported with the inclusion of the radio-loud QSOs in the FIRST survey, although the total number of DLAs is still small (4) and the result is currently only significant at approximately the 2σ level. Since all of the z abs ∼ zem DLAs we identify in CORALS are found towards optically bright (B < 20) QSOs, there is no strong evidence (based on these limited statistics) that this population suffers from a severe dust bias. We compare our results with those from an optically-selected, radio-quiet QSO sample in order to determine whether there is evidence for an excess of galaxies around radio-loud versus radio-quiet QSOs. We find that the n(z) of z abs ∼ zem DLAs towards radio-quiet QSOs is in agreement with the number density of intervening absorbers. This result, although currently limited by the small number statistics of our survey, supports the conclusion that radio-loud quasars are found preferentially in rich galaxy environments at high redshift. Finally, we report that one of the new z abs ∼ zem DLAs discovered by CORALS has some residual flux in the base of the Lyman α trough which may be due to Lyman α emission, either from star formation in the DLA galaxy or from gas photoionised by the QSO.

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“…• Ditto for both radio-loud and radio-quiet AGNs, including presence in a full range of environments, from groups to rich clusters, at moderate redshift (McLure & Dunlop 2001;Wold et al 2001, though with a contrary vote in favor of dense environments from Finn et al 2001). …”

Section: Half Of All Three-sigma Results Are Wrongmentioning

confidence: 99%

Astrophysics in 2001

Trimble¹,

Aschwanden²

2002

PUBL ASTRON SOC PAC

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ABSTRACT. During the year, astronomers provided explanations for solar topics ranging from the multiple personality disorder of neutrinos to cannibalism of CMEs (coronal mass ejections) and extrasolar topics including quivering stars, out-of-phase gaseous media, black holes of all sizes (too large, too small, and too medium), and the existence of the universe. Some of these explanations are probably probably true, though the authors are not betting large sums on any one. The data ought to remain true forever, though this requires a careful definition of "data" (think of the Martian canals).

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Radio-quiet quasar environments at 0.5 <= z <= 0.8

Cited by 50 publications

References 119 publications

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

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

The CORALS survey

Astrophysics in 2001

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