Abstract
We have performed an analysis of over 34,000 MgII doublets at 0.36 < z < 2.29
in Sloan Digital Sky Survey (SDSS) Data-Release 7 quasar spectra; the catalog,
advanced data products, and tools for analysis are publicly available. The
catalog was divided into 14 small redshift bins with roughly 2,500 doublets in
each, and from Monte-Carlo simulations, we estimate 50% completeness at rest
equivalent width W_r ~ 0.8 \AA. The equivalent-width frequency distribution is
described well by an exponential model at all redshifts, and the distribution
becomes flatter with increasing redshift, i.e., there are more strong systems
relative to weak ones. Direct comparison with previous SDSS MgII surveys reveal
that we recover at least 70% of the doublets in these other catalogs, in
addition to detecting thousands of new systems. We discuss how these surveys
come by their different results, which qualitatively agree but, due to the very
small uncertainties, differ by a statistically significant amount. The
estimated physical cross-section of MgII-absorbing galaxy halos increased
three-fold, approximately, from z = 0.4 --> 2.3, while the W_r >= 1 \AA
absorber line density grew, dN_MgII/dX, by roughly 45%. Finally, we explore the
different evolution of various absorber populations---damped Lyman-alpha
absorbers, Lyman-limit systems, strong CIV absorbers, and strong and weaker
MgII systems---across cosmic time (0 < z < 6).
Description
[1308.5971] Precious Metals in SDSS Quasar Spectra II: Tracking the Evolution of Strong, 0.4 < z < 2.3 MgII Absorbers with Thousands of Systems
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