The structure of dark and luminous matter in early-type galaxies

Abstract

In this thesis we explore new techniques to study the dark and luminous matter in the outskirts of galaxies. To determine the mass and shape of the dark matter halo around the early-type galaxy NGC 2974, we measure the kinematics of its large neutral gas ring. We combine these large-scale kinematics with the central kinematics of the ionised gas to construct mass models of this galaxy. For galaxies that do not contain neutral gas, we use integral-field spectroscopy to measure the stellar kinematics at large radii. Briefly, we use the spectrograph as a "photon-collector", to obtain spectra with sufficient signal-to-noise. The kinematics are used to model the dark haloes around the galaxies NGC 2549, NGC 3379 and NGC 821. We also measure the line strengths from the spectra to determine the properties of the stellar population in the outer parts of these systems. Finally, we take a look in the high-redshift Universe, by studying the Lyman Alpha emission of a system at redshift 3.1 (LAB1). We obtain integral-field spectra to study the distribution of the ionised gas, as well as the emission profile, and discuss possible formation and ionisation scenarios.