Assessing the Potential of Intervening MgII Absorbers for Cosmology

Abstract

In this thesis I present a method of using intervening MgII absorbers as a way toprobe the large scale structure (LSS) of the universe. In addition, I discuss the usesof intervening MgII absorbers as a tool for cosmology.Due to the large amounts of telescope time required to observe faint and distantgalaxies, it becomes increasingly difficult to map the LSS of the universe at highredshifts. With the intervening MgII method presented here it is possible, with anindependent method, to map the LSS of the universe and begin to understand theearly stages of formation and evolution of the LSS of the universe.I use six known examples of high redshift structures to assess whether interveningMgII absorbers can highlight the LSS. In five of the six target fields, there aredetections of dense regions of MgII absorbers which are believed to be in associationwith the target structures, while the sixth target remains less clear due to lowcompleteness. In one particular case, a long, thin, dense arc of absorbers is foundextending up to 1 Gpc atz∼0.8. A structure of such size could potentially challengethe standard model of cosmology. In addition, further similar structures may exist,awaiting to be detected with the MgII method presented here. For the final target, Iuse the MgII method to refine the redshift measurement of a known
chain of galaxyclusters in association with a large quasar group.The aim of this thesis was to assess the potential of using intervening MgIIabsorbers as a tool for cosmology and LSS. The conclusion is this new method doesindeed have considerable potential for cosmological investigations.