2017/01/19 by Nigel L. Mathes, Nigel Mathes, Christopher W. Churchill +5 · 1 citation
Engineering · Physics and Astronomy · #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #Space Satellite Systems and Control #Spacecraft Design and Technology #astro-ph.GA
paper · pdf · doi:10.48550/arxiv.1701.05624
15 pages, 10 figures
arxiv created 2017/01/19 · openalex publication_date 2017/01/19 · arxiv updated 2017/01/23 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We present detailed measurements of the redshift path density, equivalent width distribution, column density distribution, and redshift evolution of \MgII absorbers as measured in archival spectra from the UVES spectrograph at the Very Large Telescope (VLT/UVES) and the HIRES spectrograph at the Keck Telescope (Keck/HIRES) to equivalent width detection limits below 0.01~Å. This survey examines 432 VLT/UVES spectra from the UVES SQUAD collaboration and 170 Keck/HIRES spectra from the KODIAQ group, allowing for detections of intervening \MgII absorbers spanning redshifts 0.1 < z < 2.6. We employ an accurate, automated approach to line detection which consistently detects redshifted absorption lines. We measure the equivalent widths, apparent optical depth column densities, and velocity widths for each absorbing system. Using our complete sample of all detectable \MgII absorbers, we can accurately determine the redshift path density of absorbers across cosmic time. We measure evolution in the comoving \MgII line density, dN /dX, finding more high equivalent width absorbers at z = 2 than at present. We also measure evolution in the equivalent width distribution, parameterized by a Schechter function fit, finding a shallower weak-end slope for absorbers at redshifts between 1.53 < z < 2.64 as compared to lower redshifts. Finally, we calculate the cosmic mass fraction of \MgII using the column density distribution. We find that weak \MgII absorbers, those with equivalent widths less than 0.3~Å, are physically distinct and evolve separately from very strong \MgII absorbers, which have equivalent widths greater than 1.0~Å.