Measuring the halo mass of MgII absorbers from their cross-correlation with luminous red galaxies
N. Bouché¹, M. T. Murphy², C. Péroux³, I. Csabai^4
1 Max Planck Institute fur extraterrestrische Physik, Garching, Germany
² Institute for Astronomy, Cambridge, UK ³ European Southern Observatory
⁴ Eötvös Loránd University, Budapest, Hungary

In order to measure the mass of MgII quasar absorption systems, we measured the cross-correlation between ~ 1800 MgII systems and ~ 250,000 Luminous Red Galaxies (LRGs) selected from the Sloan Digital Sky Survey (SDSS) Data Release 3 in the redshift range 0.4 £ z £ 0.8. Over comoving scales 0.05-13h^-1 Mpc, the MgII-LRG cross-correlation has an amplitude 0.75 times that of the LRG-LRG auto-correlation. Since LRGs have halo masses around 10¹³ M\odot, our results imply that the MgII absorber host-galaxies have halo masses 1-2 ~ 10¹². Our results are consistent with those of Steidel, Dickinson & Persson (1994) who found that MgII absorbers with W _r^MgII ³ 0.3 Å are associated with ~ 0.7L_B^* galaxies. Surprinsingly, subsamples divided according to their MgII equivalent widths show that equivalent width is anticorrelated with halo mass.

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On 20 Oct 2005, 15:49.