Mathematics – Logic
Scientific paper
Nov 2005
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2005phdt.........8m&link_type=abstract
Ph.D dissertation, 2005. Section 0244, Part 0606 241 pages; Canada: University of Victoria (Canada); 2005. Publication Number:
Mathematics
Logic
Intracluster, Active Galactic Nucleus
Scientific paper
Clusters of galaxies are the largest and most massive virialized objects in the universe. And because structure formation in the universe occurs hierarchically, clusters represent the end points of this process. As a result, these systems contain a wealth of cosmological information including a detailed fossil record of the structure formation process. However, in order to fully exploit clusters for cosmological purposes, it is necessary to model the internal properties of these systems in detail, particularly the baryonic component. Although much progress has been made on this front, there remain several important outstanding issues in our understanding of the properties of the intracluster medium (ICM), a diffuse plasma that fills clusters and dominates (by mass) the baryonic component of these systems. In particular, very little is presently known about the potential role of non-gravitational ICM physics such as radiative cooling, thermal conduction, and heating via outflows from supermassive black holes (i.e., active galactic nuclei - AGN) that are often located at the centers of clusters.
In this dissertation, we have attempted to shed light on this important issue. In particular, we have developed physically-motivated analytic models of the ICM in order to assess the role that non-gravitational processes, such as radiative cooling and heating from AGN, play in mediating the observed properties of clusters. We have carried out detailed and systematic comparisons between our models and the observed global and structural X-ray and Sunyaev- Zeldovich (SZ) effect properties of clusters. From this comparison we conclude the following. As expected, a pure gravitational model (i.e., the standard self-similar model) fails to match the observed properties of clusters. A model that invokes radiative cooling but no sources of non-gravitational heating also fails, as it has no hope of avoiding the so-called "cooling crisis" or of explaining the origin of "non-cooling flow" clusters. On the other hand, a model that includes non-gravitational heating but that does not take into account the effects of radiative cooling fails to account for the observed global and structure properties of "cooling flow" clusters and obviously has no hope of explaining galaxy or star formation in clusters. We find that in order to account for the global X-ray and SZ effect scaling relations (including their intrinsic scatter), it is necessary to invoke both radiative cooling and a distribution in the level of non-gravitational heating experienced by clusters. Under this scenario, clusters that were severely heated early on likely evolved into "non-cooling flow" clusters, whereas clusters that were heated by only mild amounts likely evolved into "cooling flow" clusters. This conclusion is reinforced by comparisons to new spatially-resolved entropy, temperature, and surface brightness profiles derived from Chandra and XMM- Newton X-ray data.
No associations
LandOfFree
Probing the physics of the intracluster medium does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Probing the physics of the intracluster medium, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Probing the physics of the intracluster medium will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1652808