Master Thesis Defense by Jesper Larsen

Title: Automated Analysis and of Damped Lyman-alpha Systems Found in Spectra of Background Quasars

Abstract:

This thesis present a program developed for automated spectral analysis of QSO spectra, in preparation for the upcoming 4MOST-Gaia Purely Astronomic Quasar Survey. The program is written from scratch exclusively in Python 3, and can automatically redshifts of QSOs and located Damped Lymanα absorption system within their spectra. It applies a step-by-step method similar to old fashioned visual inspection, where the problem is decomposed in to small, less complex parts.

Tested on simulated spectra with SNR ≥ 10 in the 7700-8500 ˚A interval, the code is able to accurately determine redshifts of QSOs more than 90% of the time to within 0.05 for spectra at z ≥ 3. Within the same spectra, the code correctly detects DLAs more than 77% of the time at z = 3, declining to ≥39% at z = 5. In its current state, the code is unlikely to function as a primary source of spectral analysis, but could work as source of additional confirmation with regards to redshift determination and detection of DLAs.

Supervisor:

• Lise Christensen, University of Copenhagen, Niels Bohr Institute

Censor:

• Frank Grundahl, Aarhus University