Detecting Multiple DLAs per Spectrum in SDSS DR12 with Gaussian Processes

Understand

We present a revised version of our automated technique using Gaussian processes (GPs) to detect Damped Lyman-$\alpha$ absorbers (DLAs) along quasar (QSO) sightlines.

• The main improvement is to allow our Gaussian process pipeline to detect multiple DLAs along a single sightline.
• Our DLA detections are regularised by an improved model for the absorption from the Lyman-$\alpha$ forest which improves performance at high redshift.
• We also introduce a model for unresolved sub-DLAs which reduces mis-classifications of absorbers without detectable damping wings.