The impact of ionized outflows on the surrounding interstellar medium in disc galaxies

The aim of this thesis was to study the evolution of spiral galaxies by quantifying the impact of the ionized outflows in spiral galaxies on the surrounding interstellar medium. This project was based on optical Fabry-P´erot and long-slit observations with the instrument RSS (Robert Stobie Spectrograph) at the 10 m Southern African Large Telescope (SALT). I focussed on two types of nearby spirals, the first of which is a face-on spiral galaxy (NGC 300) in order to study the kinematics of outflows from Hii regions, and their impact on their surroundings as well as the present-day chemical abundances across these areas. I used the CLOUDY model to compare with my results in order to quantify the conditions in these areas. The second object was the Seyfert 2 galaxy NGC 4945, which shows high activity in the centre (AGN and starburst). I studied the physical properties of the ionize dejected material, their kinematics and morphology. I presented a first kinematic map for the central area based on Fabry-P´erot observations of H_ and [N II]. The shapes of emission lines in this area were analysed to estimate the physical conditions in the areas of interest. The final chapter shows preliminary results of an on-going optical and radio survey for a sample of 36 Southern edge-on disc galaxies in order to study the disc−halo interface by tracing extended ionized extraplanar gas. My results from the previous three projects show that the outflows from Hii regions and AGN and/or starburst play an important role in re-shaping the surrounding ISM by forming filaments or shells. The kinematics of the surrounding gas are affected by the outflows also. My results suggest that the ionized ejected material from the centre of NGC 4945 forms a bi-conal structure, and I constructed a model for the shape of the bi-cone according to my results