The Dark Matter Haloes and Host Galaxies of MgII Absorbers at z~1
  Strong foreground absorption features from singly-ionized Magnesium (Mg II)
are commonly observed in the spectra of quasars and are presumed to probe a
wide range of galactic environments. To date, measurements of the average dark
matter halo masses of intervening Mg II absorbers by way of large-scale
cross-correlations with luminous galaxies have been limited to z<0.7. In this
work we cross-correlate 21 strong (W{\lambda}2796>0.6 {\deg}A) Mg II absorption
systems detected in quasar spectra from the Sloan Digital Sky Survey Data
Release 7 with ~32,000 spectroscopically confirmed galaxies at 0.7<z<1.45 from
the DEEP2 galaxy redshift survey. We measure dark matter (DM) halo biases of
b_G=1.44\pm0.02 and b_A=1.49\pm0.45 for the DEEP2 galaxies and Mg II absorbers,
respectively, indicating that their clustering amplitudes are roughly
consistent. Haloes with the bias we measure for the Mg II absorbers have a
corresponding mass of 1.8(+4.2/-1.6) \times 10^12h-1M_sun, although the actual
mean absorber halo mass will depend on the precise distribution of absorbers
within DM haloes. This mass estimate is consistent with observations at z=0.6,
suggesting that the halo masses of typical Mg II absorbers do not significantly
evolve from z~1. We additionally measure the average W{\lambda}2796>0.6 \AA gas
covering fraction to be f =0.5 within 60 h-1kpc around the DEEP2 galaxies, and
we find an absence of coincident strong Mg II absorption beyond a projected
separation of ~40 h-1kpc. Although the star-forming z>1 DEEP2 galaxies are
known to exhibit ubiquitous blueshifted Mg II absorption, we find no direct
evidence in our small sample linking W{\lambda}2796>0.6 \AA absorbers to
galaxies with ongoing star formation.
