An excess of damped Lyman   galaxies near quasi-stellar objects

Russell, D. M.; Ellison, Sara L.; Benn, Chris

doi:10.1111/j.1365-2966.2005.09964.x

Cited by 34 publications

(44 citation statements)

References 61 publications

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“…Although the line density of proximate super-LLSs near quasar has yet to be mea- sured (but see Prochter, , it is incontrovertible that 15 − 50% percent of quasars do not show a super-LLS within ∆v < 3000 km s −1 along the line of sight. Russell et al (2006) recently measured the line density of proximate DLAs (log N HI > 20.3) with ∆v < 3000 km s −1 from 731 SDSS quasars. The median redshift of their quasar sample was z = 3.335 and they found dN/dz = 0.38 +0.18 −0.08 .…”

Section: Anisotropic Clustering Of Absorbers Around Quasarsmentioning

confidence: 99%

“…Møller et al 1998). Recently, Russell et al (2006) (see also Ellison et al 2002), compared the number density of proximate DLAs per unit redshift to the average number density of DLAs in the the Universe (Prochaska et al 2005). They found that the abundance of DLAs is enhanced by a factor of ∼ 2 near quasars, which they attributed to the clustering of DLA-galaxies around quasars.…”

Section: Introductionmentioning

confidence: 99%

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Quasars Probing Quasars. II. The Anisotropic Clustering of Optically Thick Absorbers around Quasars

Prochaska

2007

ApJ

137

180

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With close pairs of quasars at different redshifts, a background quasar sightline can be used to study a foreground quasar's environment in absorption. We used a sample of 17 Lyman limit systems with column density N HI > 10 19 cm −2 selected from 149 projected quasar pair sightlines, to investigate the clustering pattern of optically thick absorbers around luminous quasars at z ∼ 2.5. Specifically, we measured the quasar-absorber correlation function in the transverse direction, and found a comoving correlation length of r 0 = 9.2 +1.5 −1.7 h −1 Mpc (comoving) assuming a power law correlation function, ξ ∝ r −γ , with γ = 1.6. Applying this transverse clustering strength to the line-of-sight, would predict that ∼ 15 − 50% of all quasars should show a N HI > 10 19 cm −2 absorber within a velocity window of ∆v < 3000 km s −1 . This overpredicts the number of absorbers along the line-of-sight by a large factor, providing compelling evidence that the clustering pattern of optically thick absorbers around quasars is highly anisotropic. The most plausible explanation for the anisotropy is that the transverse direction is less likely to be illuminated by ionizing photons than the line-of-sight, and that absorbers along the line-of-sight are being photoevaporated. A simple model for the photoevaporation of absorbers subject to the ionizing flux of a quasar is presented, and it is shown that absorbers with volume densities n H 0.1 cm −3 will be photoevaporated if they lie within ∼ 1 Mpc (proper) of a luminous quasar. Using this simple model, we illustrate how comparisons of the transverse and line-of-sight clustering around quasars can ultimately be used to constrain the distribution of gas in optically thick absorption line systems.

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Section: Anisotropic Clustering Of Absorbers Around Quasarsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Quasars Probing Quasars. II. The Anisotropic Clustering of Optically Thick Absorbers around Quasars

Prochaska

2007

ApJ

137

180

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“…This δv was chosen to exclude 'proximate' DLAs, whose incidence rate is likely affected by a combination of ionizing radiation from the background QSO and the overdensity associated with the QSO host galaxy halo (e.g. Ellison et al 2002Ellison et al , 2010Russell, Ellison & Benn 2006;Prochaska, Hennawi & Herbert-Fort 2008). Table 3 lists the redshift path limits used for each QSO in the GGG sample.…”

Section: Procedures For Identifying Dlasmentioning

confidence: 99%

The neutral hydrogen cosmological mass density atz= 5

Crighton¹,

Murphy²,

Prochaska³

et al. 2015

Mon. Not. R. Astron. Soc.

171

158

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“…PDLAs are defined as those DLAs lying within 5000 km s −1 (or sometimes 3000 km s −1 ) of the redshift of the background QSO (Møller et al 1998;Ellison et al 2002Ellison et al , 2010Ellison et al , 2011Russell et al 2006;Rix et al 2007;Prochaska et al 2008). They are frequently excluded from studies of intervening DLAs, due to their potentially unusual ionization conditions and environmental effects (such as galaxy clustering near quasars).…”

Section: Introductionmentioning

confidence: 99%

High-ion absorption in the proximate damped Ly-αsystem toward Q0841+129

Ledoux¹,

Petitjean²,

Srianand³

et al. 2011

A&A

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We present VLT/UVES spectroscopy of the quasar Q0841+129, whose spectrum shows a proximate damped Ly-α (PDLA) absorber at z = 2.47621 and a proximate sub-DLA at z = 2.50620, both lying close in redshift to the QSO itself at z em = 2.49510 ± 0.00003. This fortuitous arrangement, with the sub-DLA acting as a filter that hardens the QSO's ionizing radiation field, allows us to model the ionization level in the foreground PDLA, and provides an interesting case-study on the origin of the high-ion absorption lines Si iv, C iv, and O vi in DLAs. The high ions in the PDLA show at least five components spanning a total velocity extent of ≈160 km s −1 , whereas the low ions exist predominantly in a single component spanning just 30 km s −1 . We examine various models for the origin of the high ions. Both photoionization and turbulent mixing layer models are fairly successful at reproducing the observed ionic ratios after correcting for the non-solar relative abundance pattern, though neither model can explain all five components. We show that the turbulent mixing layer model, in which the high ions trace the interfaces between the cool PDLA gas and a hotter phase of shock-heated plasma, can explain the average high-ion ratios measured in a larger sample of 12 DLAs.

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An excess of damped Lyman galaxies near quasi-stellar objects

Cited by 34 publications

References 61 publications

Quasars Probing Quasars. II. The Anisotropic Clustering of Optically Thick Absorbers around Quasars

Quasars Probing Quasars. II. The Anisotropic Clustering of Optically Thick Absorbers around Quasars

The neutral hydrogen cosmological mass density atz= 5

High-ion absorption in the proximate damped Ly-αsystem toward Q0841+129

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