Unveiling the globular cluster systems of early-type galaxies: A wide-field imaging study of early-type galaxies to investigate their evolutionary history

Globular cluster (GC) systems can be used as powerful tools to investigate the evolutionary history of early-type galaxies (ETGs). In this work, we study the GC systems of five ETGs using wide-field imaging data. We obtained the data from the Subaru telescope, the Canada-France-Hawaii telescope and the Hubble Space Telescope. Complementary spectroscopic data from the Keck II telescope were also utilised for this thesis. We present a wide-field imaging study of GC systems in five ETGs (NGC 720, NGC 1023, NGC 2768, NGC 3607 and NGC 3608) to determine their GC system properties. With the aid of literature data, we present a new correlation of GC system extent with host galaxy eeffective radius. We find a dependence of the relative fraction of blue to red GCs with host galaxy environmental density for lenticular galaxies (but not for elliptical or spiral galaxies). We propose that tidal interactions between galaxies in cluster environments might be the reason behind the observed trend for lenticular galaxies. A one-to-one relation between the ellipticities of red GCs and the galaxy stellar light emphasises the evolutionary similarities between them.

Sreeja S. Kartha was born in Pala, a small town near Kottayam, Kerala. She achieved the doctoral degree in astrophysics from Swinburne University of Technology, Australia. Her research topic was the wide-field imaging studies of globular clusters in ETGs. She completed the bachelor's and master's degrees in Physics from M. G. University, Kottayam.