The association between gas and galaxies III: the cross-correlation of galaxies and Ly alpha absorbers at z similar to 1

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Title: The association between gas and galaxies III: the cross-correlation of galaxies and Ly alpha absorbers at z similar to 1
Author(s): Shone, Allen M.; Morris, Simon L.; Crighton, Neil; Wilman, Richard J.
Abstract: We have measured the two-dimensional two-point correlation function, ξAG , between low-column-density Lyα absorbers and galaxies at a redshift z∼ 1 . We measured Lyα absorbers between redshifts z= 0.68 and 1.51 over a total redshift path length of Δz= 1.08 from Hubble Space Telescope Space Telescope Imaging Spectrograph E230M absorption spectra towards the quasars HE 1122− 1648 (z= 2.4) and PKS 1127− 145 (z= 1.187) . The column density of the Lyα absorbers ranged from 13.2 ≤ log10 [NH I(cm−2)] ≤ 17.4 , with a median column density of log10 [NH I(cm−2)] = 14.0 . A total of 193 galaxy redshifts within the surrounding 6.8 × 5.7 arcmin2 field of view of both quasars were identified in a R -magnitude-limited survey (21.5 ≤RVega≤ 24.5) using the Focal Reducer and Low Dispersion Spectrograph (FORS2) at the Very Large Telescope, of which 95 were higher than the minimum redshift of z= 0.68 to be used in the correlation function. A 3σ upper limit of ξAG= 2.8 was found when 145 Lyα absorber–galaxy pairs were binned in redshift space, in a bin of size Δσ= 1.0, Δπ= 2.0 h−170 Mpc along the projected separation and line-of-sight distances, respectively. The upper limit in the cross-correlation was found to be 5.4σ lower than the central peak in the galaxy autocorrelation within the same redshift range, ξGG , which was in our data equal to 10.7 ± 1.4 . Thus, we have shown for the first time that the clustering between low-column-density absorbers and galaxies at a redshift of 1 is weaker than that between galaxies at the same redshift.
Publication type: Journal article
Research centre: Swinburne University of Technology. Faculty of Information and Communication Technologies. Centre for Astrophysics and Supercomputing
Source: Monthly Notices of the Royal Astronomical Society, Vol. 402, no. 4 (Mar 2010), pp. 2520-2538
Publication year: 2010
FOR Code(s): 0201 Astronomical and Space Sciences
Keyword(s): Absorption lines; Galaxy haloes; Intergalactic medium; Quasars
Publisher: Wiley-Blackwell Publishing
ISSN: 0035-8711
Publisher URL: http://dx.doi.org/10.1111/j.1365-2966.2009.16056.x
Peer reviewed