Intervening absorption–line systems in the very–high signal–to–noise VLT/UVES spectrum of the QSO HE 0940–1050

Abstract

Distant, compact, and extremely luminous light sources such as quasars provide a wealth of information regarding the history of the universe through the analysis of intervening absorption line systems as they trace the filaments of the cosmic web. These absorption systems are intergalactic clouds identified through metal absorption lines observed on certain absorption redshifts, located between us and the background source. The cumulative analysis of intervening absorption line systems helps us map the universe and better understand the dynamical and chemical evolution of galaxies through the utilization of the gas content of these systems, eventually learning about the different gas phases of the universe and the origin of intergalactic metals. We have searched for systems of metal absorption lines with doublet/multiplet transitions as these can be easily detected in quasars spectra, where most of our species come from the UV regime; they can be considered a powerful tool to investigate the sightlines of distant sources since these lines get shifted to the visible part of spectra at high–redshifts. Implementing the very–high S/N spectrum of the VLT/UVES with automated and stochastic evolutionary algorithms, which requires minimum initialization, we curve–fitted and investigated 20 absorption line systems along the line–of–sight of the well–studied quasar HE 0940–1050 at z_em = 3.076. The simultaneous optimization of the radial velocity, line broadening, and the logarithmic column density of absorption line profiles managed us to detect and fit very complex profiles seen for the first time at absorption systems already identified in the literature. This is along with the detection of blended components of different populations at absorption systems which used to be considered a single population of an absorber, and the detection of extremely weak components down to log (N /cm –2 ) < 11.