The Pittsburgh Sloan Digital Sky Survey MgII Quasar Absorption-Line Survey Catalog

TL;DR

This paper introduces a comprehensive catalog of over 17,000 MgII quasar absorption-line systems from SDSS DR4, enabling detailed studies of galaxy gas at various redshifts.

Contribution

The paper provides the first large, well-characterized catalog of MgII absorbers from SDSS DR4, including detailed data and detection thresholds for statistical analysis.

Findings

Catalog contains >17,000 MgII systems.

Includes data on ~44,600 spectra with redshift and magnitude info.

Estimated 1 in 100 MgII systems might be missed due to detection limits.

Abstract

We present a catalog of intervening MgII quasar absorption-line systems in the redshift interval 0.36 <= z <= 2.28. The catalog was built from Sloan Digital Sky Survey Data Release Four (SDSS DR4) quasar spectra. Currently, the catalog contains > 17,000 measured MgII doublets. We also present data on the ~44,600 quasar spectra which were searched to construct the catalog, including redshift and magnitude information, continuum-normalized spectra, and corresponding arrays of redshift-dependent minimum rest equivalent widths detectable at our confidence threshold. The catalog is available on the web. A careful second search of 500 random spectra indicated that, for every 100 spectra searched, approximately one significant MgII system was accidentally rejected. Current plans to expand the catalog beyond DR4 quasars are discussed. Many MgII absorbers are known to be associated with galaxies. Therefore, the combination of large size and well understood statistics makes this catalog ideal for precision studies of the low-ionization and neutral gas regions associated with galaxies at low to moderate redshift. An analysis of the statistics of MgII absorbers using this catalog will be presented in a subsequent paper.