A High Resolution Study of the LINER Galaxy NGC5218

Licentiate thesis, 2006

Low Ionisation Nuclear Emission-line Regions (LINERs)are found in one third of the galaxies in the local bright galaxy population. The LINERs typically recide in the central parts of their host galaxies, and occur in early type elliptical galaxies as well as late type spiral galaxies. Hence, galaxies containing LINERs make up a rather inhomogenous, and not yet well understood class. The definition of the LINER is based on ratios between emission lines at optical wavelengths. The ratios indicate the degree of ionisation in the gas responsible for the emission lines. Similar optical emission line ratios are used to define the classes of Starburst and Seyfert galaxies. The Starburst galaxies are characterised by recent or ongoing bursts of star formation, which typically give rise to a strong Hα emission line that is not found in the LINER galaxies. Seyfert galaxies are characterised by accretion of gas and dust onto a compact central super massive body - and is said to contain an Active Galactive Nucleus, AGN. The LINER spectrum at optical wavelengths has similarities with spectra from both Starburst galaxies and Seyfert Galaxies, which raises the question whether LINERs are typically driven by starbursts, an AGN, a combination, or something else. In this thesis......