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Title: Damped Lyman-α absorbers from Sloan digital sky survey DR16Q with Gaussian processes
ABSTRACT We present a new catalogue of Damped Lyman-α absorbers from SDSS DR16Q, as well as new estimates of their statistical properties. Our estimates are computed with the Gaussian process models presented in Garnett et al., Ho, Bird & Garnett with an improved model for marginalizing uncertainty in the mean optical depth of each quasar. We compute the column density distribution function (CDDF) at 2 < z < 5, the line density (dN/dX), and the neutral hydrogen density (ΩDLA). Our Gaussian process model provides a posterior probability distribution of the number of DLAs per spectrum, thus allowing unbiased probabilistic predictions of the statistics of DLA populations even with the noisiest data. We measure a non-zero column density distribution function for $$N_{\rm {HI}}\lt 3 \times 10^{22} \, \rm {cm}^{-2}$$ with $$95{{\ \rm per\ cent}}$$ confidence limits, and $$N_{\rm {HI}}\lesssim 10^{22} \, \rm {cm}^{-2}$$ for spectra with signal-to-noise ratios >4. Our results for DLA line density and total hydrogen density are consistent with previous measurements. Despite a small bias due to the poorly measured blue edges of the spectra, we demonstrate that our new model can measure the DLA population statistics when the DLA is in the Lyman-β forest region. We verify our results are not sensitive to the signal-to-noise ratios and redshifts of the background quasars although a residual correlation remains for detections from zQSO < 2.5, indicating some residual systematics when applying our models on very short spectra, where the SDSS spectral observing window only covers part of the Lyman-α forest.  more » « less
Award ID(s):
1817256 1845434
PAR ID:
10289367
Author(s) / Creator(s):
; ;
Date Published:
Journal Name:
Monthly Notices of the Royal Astronomical Society
Volume:
507
Issue:
1
ISSN:
0035-8711
Page Range / eLocation ID:
704 to 719
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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