Detecting multiple DLAs per spectrum in SDSS DR12 with Gaussian processes
Abstract
We present a revised version of our automated technique using Gaussian processes (GPs) to detect damped Lyman α absorbers (DLAs) along quasar (QSO) sightlines. The main improvement is to allow our GP pipeline to detect multiple DLAs along a single sightline. Our DLA detections are regularized by an improved model for the absorption from the Lyman α forest that improves performance at high redshift. We also introduce a model for unresolved sub-DLAs that reduces misclassifications of absorbers without detectable damping wings. We compare our results to those of two different large-scale DLA catalogues and provide a catalogue of the processed results of our GP pipeline using 158 825 Lyman α spectra from SDSS data release 12. We present updated estimates for the statistical properties of DLAs, including the column density distribution function, line density (dN/dX), and neutral hydrogen density (ΩDLA).
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- August 2020
- DOI:
- 10.1093/mnras/staa1806
- arXiv:
- arXiv:2003.11036
- Bibcode:
- 2020MNRAS.496.5436H
- Keywords:
-
- methods: statistical;
- intergalactic medium;
- quasars: absorption lines;
- galaxies: statistics;
- Astrophysics - Cosmology and Nongalactic Astrophysics;
- Astrophysics - Astrophysics of Galaxies;
- Physics - Data Analysis;
- Statistics and Probability
- E-Print:
- 24 pages, 20 figures, plus 3 tables of figure values. Minor changes to match version published in MNRAS. Code available in https://github.com/rmgarnett/gp_dla_detection/tree/master/multi_dlas