active galactic nuclei

In this thesis I study the inner-most regions of Active Galactic Nuclei (AGN) using the reverberation mapping technique, and neutron star low-mass X-ray binaries in quiescence using X-ray observations. Using the 13-year optical monitoring data for the AGN NGC 5548, the luminosit…

X-ray surveys are an effective way to study growing supermassive black holes (SMBHs) in galaxy centers, as actively accreting SMBHs manifest themselves as active galactic nuclei (AGN) that can be observed in the X-ray in most cases. Through studying AGNs in X-ray survey fields t…

While supermassive black holes (SMBHs) up to a billion times the mass of the Sun are found in the centers of all massive galaxies and stellar mass black holes of ~ 10 solar masses (M☉) are formed from supernovae, there is currently no direct evidence for intermediate mass black …

Galaxies have existed for the majority of the lifetime of the Universe, having first formed 400-1000 Myr after the Big Bang, and it is known that most galaxies contain supermassive black holes (SMBHs) at their centres. In recent years, correlations have been found between the ev…

Most of the baryons, or “normal" matter, found in galaxies and galaxy clusters are found in the hot, X-ray emitting gas known as the circumgalactic medium (CGM) or intracluster medium (ICM). The hot gas traces the gravitational potential well and is affected by both thermal and …

In this thesis, we aim to understand the history of active galactic nuclei (AGN). AGN typically are observed while the central black hole is actively accreting. While these are essential measurements, they do not allow us to examine a host galaxy after the active phase has compl…