Processes affecting the dynamics and x-ray emission of galaxies and clusters of galaxies

This dissertation describes various studies of physical processes that affect the dynamics of, and X-ray emission from, galaxies and clusters of galaxies. Work done based on observations of an elliptical galaxy using two separate X- ray satellites is presented, along with theoretical studies of high-energy emission from clusters of galaxies and the cumulative effect of mergers on clusters.

Chandra and XMM-Newton X-ray observations of the X-ray bright E2 elliptical galaxy NGC 4649 are presented. In addition to bright diffuse emission, many discrete sources are resolved, most of which are presumably low-mass X-ray binaries (LMXBs). In each case the total X-ray spectrum of the resolved sources is well-fit by a hard power-law, while the diffuse spectrum requires a hard and a soft component, presumably due to the relatively soft diffuse gas and the harder unresolved sources. We find evidence for long-term variability in some individual LMXBs, a break in the source luminosity function near the Eddington luminosity, a varying radial temperature profile in the diffuse emission, and structure in the diffuse emission.

The net effect of EUV emission from clusters of galaxies is also considered. Assuming that the source of the EUV emission is inverse Compton (IC) scattering of Cosmic Microwave Background photons by relativistic electrons, we construct a simple model for the expected average emission from clusters as a function of their mass and the redshift of interest. We find that while clusters do contribute a significant EUV background, it is less than a percent of that expected from quasars.

Finally, the effect of mergers on the X-ray luminosity and temperature functions and on the inferred mass function and cosmological parameters is considered. The boosts from individual mergers are derived from N-body/ hydrodynamical simulations of mergers. The statistics of the merger histories of clusters are determined from extended Press-Schechter (PS) merger trees. We find that merger boosts can increase the apparent number of hot, luminous clusters, and that merger boosts cause s 8 to be overestimated by about 20%. The matter density parameter O 0 may be underestimated by about 20%, although this result is less clear.