Quasars form one of the most energetic phenomena in the universe, and can be traced out to very large redshifts. By studying the galaxies which host the active nuclei, important insights can be gained into the processes that trigger and maintain the quasar powerhouse. The evolution rate of the quasar population is furthermore similar to that of ordinary galaxies, which implies a connection between black hole accretion and star formation in the host galaxies. While the properties of quasar host galaxies at low redshift have become better constrained in recent years, less is known about hosts at earlier cosmic epochs. In addition, though radio-quiet quasars are by far more common than their radio-loud counterparts their host galaxies have not been studied to the same extent, in particular not at higher redshifts.An imaging campaign of a large sample of quasars at intermediate redshift (0.4 < z < 0.8) was carried out at optical wavelengths using the Nordic Optical Telescope, and is studied in this thesis together with two smaller samples. The joint material forms more than half of the total number of observed sources in this redshift interval and increases the number of resolved radio-quiet hosts…
Contents
1 Introduction
2 Aspects of AGN
2.1 The engine
2.2 The Zoo
3 Radio properties of quasars
3.1 Radio-loud quasars
3.2 The radio dichotomy
4 Unification
5 The host galaxies of quasars
5.1 Point spread function subtraction
5.2 Host galaxies at low redshift
5.2.1 Morphology and luminosities
5.2.2 Colours and spectroscopy
5.2.3 The host-nucleus luminosity limit and black hole mass
5.3 Host galaxies at higher redshifts
5.4 Adaptive optics imaging
6 Summary of papers
6.1 Paper I and II
6.2 Paper III
7 Future work
8 Publications not included in the thesis
Acknowledgements
Appendix: Quasar host images and profiles
Author: Örndahl, Eva
Source: Uppsala University Library
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