Size estimates for intervening C IV absorbers from high resolution spectroscopy of APM 0827+5255

Abstract

A new analysis of Keck/HIRES observations of the broad absorption line QSO APM 0827+5255 indicates that a number of intervening C IV absorbers give rise to absorption lines for which the observed optical depths for 1548, 1550 A doublet components are not in the expected 2:1 ratio. To compensate for the effect, a local adjustment of the zero-level is required. We model this effect as coverage of one line of sight to this gravitationally lensed QSO and perform a set of simulations to select a sample of lines for which our model provides an explanation for the effect. We use lines in this sample to obtain estimates for minimum C IV absorber sizes from total coverage and the separations of the lines of sight for a range of lens redshifts, z_l, and two cosmologies. We also obtain best estimates for overall sizes from a statistical `hit and miss' approach. For z_l=0.7 our results set a lower limit to sizes of C IV absorbers of ~0.3 h_72^{-1} kpc (~0.5 h_72^{-1} kpc) for Omega_M=1, Omega_Lambda=0 (Omega_M=0.3, Omega_Lambda=0.7), in agreement with other results from similar work but are limited by sample size and the uncertainty in z_l. Our method can be used to detect lensed QSOs and to probe absorber sizes when separate spectra cannot be obtained for each line of sight.

14 pages, 10 figures, accepted for publication in MNRAS

References in corpus (3)

• Galactic winds in the intergalactic medium
• Spatially resolved STIS spectra of the gravitationally lensed BAL quasar APM08279+5255: the nature of component C and evidence for microlensing
• MgII Absorption Lines in z=2.974 Damped Lyman-alpha System toward Gravitationally Lensed QSO APM 08279+5255: Detection of Small-scale Structure in MgII Absorbing Clouds

Cited by in corpus (8)

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• Large-Scale Correlations in the Lyman-alpha Forest at z = 3-4
• The Origins of a Rich Absorption Line Complex in a Quasar at Redshift 3.45
• Clustering of galaxies at z=3 around the probable Damped Ly-alpha absorber towards QSO APM 08279+5255
• Transverse clues on the kpc-scale structure of the circumgalactic medium as traced by C IV absorption
• Constraining the Size of the Circumgalactic Medium Using the Transverse Autocorrelation Function of C IV Absorbers in Paired Quasar Spectra