Nikole M. Nielsen, Christopher W. Churchill, Glenn G. Kacprzak
We fully characterize the MgII absorbing circumgalactic medium (CGM) using the "MgII Absorber-Galaxy Catalog" (MAGIICAT), a compilation comprising 169 intermediate redshift (0.1 < z < 1.1) galaxies within 200 kpc (projected) of background quasars. We examine the rest-frame equivalent widths, Wr(2796), and covering fractions, f_c, down to Wr(2796) ~ 0.003 Angstroms, against galaxy redshift, B- and K-band luminosity, B-K color, and impact parameter, D. We also present B- and K-band luminosity functions for different Wr(2796) and redshift regimes. The radial extent of the MgII absorbing CGM, R(L)=R*(L/L*)^beta, exhibits little dependency on Wr(2796) threshold in the B-band, but becomes less sensitive to luminosity in the K-band. In both the B- and K-bands, R(L) has a much steeper luminosity dependence for bluer galaxies than for redder galaxies, and for lower redshift galaxies compared to higher redshift galaxies. The covering fractions exhibit clear differential dependencies on Wr(2796) threshold, galaxy luminosity, and redshift as a function of impact parameter. Lower luminosity galaxies exhibit no MgII absorption beyond 100 kpc, whereas higher luminosity galaxies have 0.1 < f_c < 0.3 beyond 100 kpc, with f_c decreasing with increasing Wr(2796) threshold. Redshift evolution is found in the B-band luminosity function for galaxies associated with Wr(2796) < 0.3 Angstroms absorption. Many of our findings are in conflict with previously published works. We address these conflicts and discuss the implications of our results for the low-ionization, intermediate redshift CGM.
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http://arxiv.org/abs/1211.1380
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