García, LÁ;
Martini, P;
Gonzalez-Morales, AX;
Font-Ribera, A;
Herrera-Alcantar, HK;
Aguilar, JN;
Ahlen, S;
... Zhou, Z; + view all
(2023)
Analysis of the impact of broad absorption lines on quasar redshift measurements with synthetic observations.
Monthly Notices of the Royal Astronomical Society
, 526
(4)
pp. 4848-4859.
10.1093/mnras/stad2993.
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Abstract
Accurate quasar classifications and redshift measurements are increasingly important to precision cosmology experiments. Broad absorption line (BAL) features are present in 15-20 per cent of all quasars, and these features can introduce systematic redshift errors, and in extreme cases produce misclassifications. We quantitatively investigate the impact of BAL features on quasar classifications and redshift measurements with synthetic spectra that were designed to match observations by the Dark Energy Spectroscopic Instrument (DESI) survey. Over the course of 5 yr, DESI aims to measure spectra for 40 million galaxies and quasars, including nearly three million quasars. Our synthetic quasar spectra match the signal-to-noise ratio and redshift distributions of the first year of DESI observations, and include the same synthetic quasar spectra both with and without BAL features. We demonstrate that masking the locations of the BAL features decreases the redshift errors by about 1 per cent and reduces the number of catastrophic redshift errors by about 80 per cent. We conclude that identifying and masking BAL troughs should be a standard part of the redshift determination step for DESI and other large-scale spectroscopic surveys of quasars.
| Type: | Article |
|---|---|
| Title: | Analysis of the impact of broad absorption lines on quasar redshift measurements with synthetic observations |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1093/mnras/stad2993 |
| Publisher version: | https://doi.org/10.1093/mnras/stad2993 |
| Language: | English |
| Additional information: | This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | methods: numerical, techniques: spectroscopic, (galaxies:) quasars: absorption |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10182003 |
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