My thesis, Structure in the cores of galaxy clusters, can be downloaded here as separate chapters or the entire thesis [6.6MB].
This thesis is Copyright © Jeremy Sanders 2002. Permission is granted for printing copies for personal study. This thesis was submitted for the degree of Doctor of Philosophy to the University of Cambridge.
This dissertation explores the structure in the cores of clusters of galaxies. Galaxy clusters are the largest gravitationally bound objects in the universe, emitting X-ray radiation from a hot (2-10 x 10^7 K) intracluster medium (ICM). In the centres of many of these clusters the mean radiative cooling time of the ICM is short (< 10^7-10^8 yr), therefore gas is expected to be cooling out of the X-ray band. More gas should then flow in under pressure to replace that which is deposited. Those clusters with evidence for cooling gas (a highly peaked luminosity profile) are known as cooling flow clusters.
I start by summarising the current understanding of the subject, and the observational evidence for it. An analysis of a sample of clusters using ROSAT archival data is then made, to look for the spectral evidence of cool gas and absorbing material in their cores, using the method of X-ray colours. Next, I discuss an original method developed to analyse spatial and spectral data from clusters, adaptive binning, which gives similar levels of signal to noise in each spatial bin. Such an algorithm is necessary to interpret the sub-arcsec resolution images of nearby clusters taken by the Chandra X-Ray Observatory.
I analyse a Chandra observation of the Perseus cluster, making temperature and absorption maps from X-ray colours, and looking at the interaction of the cooling ICM with the central radio source. For the Abell 1795 cluster I make similar maps to examine the structure of a 40 arcsec long filament found in the cluster, and hypothesise on its nature. Finally, I examine a Chandra observation of the core of the Centaurus cluster. Using imaging spectroscopy I make radial plots and maps of the temperature, absorption and metallicity distributions of the gas in the cluster. I discuss an unexpected drop in metallicity in the centre of the cluster, and also a plume-like feature found there.