Detecting and Characterizing Mg ii Absorption in DESI Survey Validation Quasar Spectra

Journal Article · 09 August 2023 · The Astronomical Journal

DOI: https://doi.org/10.3847/1538-3881/ace62c · OSTI ID:1994569

Napolitano, Lucas ; Pandey, Agnesh; Myers, Adam D.; Lan, Ting-Wen ; Anand, Abhijeet ; Aguilar, Jessica ; Ahlen, Steven ; Alexander, David M. ; Brooks, David ; Canning, Rebecca; Circosta, Chiara; De La Macorra, Axel; Doel, Peter; Eftekharzadeh, Sarah; Fawcett, Victoria A. ; Font-Ribera, Andreu ; Garcia-Bellido, Juan ; Gontcho A Gontcho, Satya ; Le Guillou, L. ; Guy, Julien ; Honscheid, Klaus; Juneau, Stephanie ; Kisner, T. ; Landriau, Martin ; Meisner, Aaron M. ; Miquel, Ramon ; Moustakas, J. ; Percival, Will J. ; Prochaska, J. Xavier ; Schubnell, Michael; Tarlé, Gregory ; Weaver, B. A.; Weiner, Benjamin ; Zhou, Zhimin ; Zou, Hu ; Zou, Siwei

Abstract We present findings of the detection of Magnesium II (Mg ii , λ = 2796, 2803 Å) absorbers from the early data release of the Dark Energy Spectroscopic Instrument (DESI). DESI is projected to obtain spectroscopy of approximately 3 million quasars (QSOs), of which over 99% are anticipated to be at redshifts greater than z > 0.3, such that DESI would be able to observe an associated or intervening Mg ii absorber illuminated by the background QSO. We have developed an autonomous supplementary spectral pipeline that detects these systems through an initial line-fitting process and then confirms the line properties using a Markov Chain Monte Carlo sampler. Based upon a visual inspection of the resulting systems, we estimate that this sample has a purity greater than 99%. We have also investigated the completeness of our sample in regard to both the signal-to-noise properties of the input spectra and the rest-frame equivalent width ( W ₀ ) of the absorber systems. From a parent catalog containing 83,207 quasars, we detect a total of 23,921 Mg ii absorption systems following a series of quality cuts. Extrapolating from this occurrence rate of 28.8% implies a catalog at the completion of the five-year DESI survey that will contain over eight hundred thousand Mg ii absorbers. The cataloging of these systems will enable significant further research because they carry information regarding circumgalactic medium environments, the distribution of intervening galaxies, and the growth of metallicity across the redshift range 0.3 ≤ z < 2.5.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); University of Michigan, Ann Arbor, MI (United States); University of Wyoming, Laramie, WY (United States)
• Sponsoring Organization: Gordon and Betty Moore Foundation; Heising-Simons Foundation; Ministry of Education, Taiwan; Ministry of Science and Innovation of Spain (MICINN); Ministry of Science and Technology (MOST); National Aeronautics and Space Administration (NASA); National Council of Science and Technology of Mexico (CONACYT); National Science Foundation (NSF); National Taiwan University; USDOE; USDOE Office of Science (SC); USDOE Office of Science (SC), High Energy Physics (HEP)
• Contributing Organization: DESI Collaboration
• Grant/Contract Number: AC02-05CH11231; SC0019022; SC0019193
• OSTI ID: 1994569
• Journal Information: The Astronomical Journal, Journal Name: The Astronomical Journal Journal Issue: 3 Vol. 166; ISSN 0004-6256
• Publisher: American Astronomical SocietyCopyright Statement
• Country of Publication: United States
• Language: English