The distribution of vision and missing mass in X-ray galaxy clusters at z < 1.4 using data of Chandra Space Observatory.
Abstract
The thesis deals with the physical properties of X-clusters of galaxies in a wide redshift range. For this research, we have selected the data of Chandra X-ray Space Observatory, namely, 128 clusters of galaxies from Abell, MACS, and RCS catalogs with the spherically symmetrical shape. We have chosen clusters with X-ray flux values at the center not lower than 7.0 x 10^-12 erg/s/cm^2, and with the exposure time of observation not less than 5000 s, with proper morphology and a wide range of redshift z < 1.4.
For each cluster, we determined the deprojected temperature and density radial profiles. In order to calculate the total mass profiles of galaxy clusters, the spherical symmetry and hydrostatic equilibrium of clusters were assumed. We modeled the total mass profile as composed of three components: the dark matter halo (fitted with a generalized Navarro-Frank-White (NFW) profile), the gaseous component, and the luminous component of the stellar component. For the density profile of dark matter (DM), we used the NFW model having a DM density profile and a mass profile, within a fixed radius. We also calculated the concentration parameter for each cluster to obtain the concentration - total mass distribution. The simplest analytic form that describes the mass-concentration relation is a power-law. We have concluded that this model gives an improved description of our sample with χ2 = 288.7 for 125 d.o.f. In order to get a slope on the combined DM profile, we summed chi-square values as a function of slope for the 128 clusters for which the NFW model provides a reasonable fit to the data. The best fit is slope = 1.10+/-0.40 (for 95 percent confidence limits). Note that three separate components (DM, gas, and stars) were included in fits. The values of the slope are in the range of 0.4-1.8 and the density profile for the largest number of clusters are compatible with the expectation from ΓCDM model (0.7-1.5). Some clusters (∼32%) have a flatter profile than the cuspy dark matter profile predicted by Lambda CDM simulations. A few clusters have the slopes smaller than 0.7 and they are usually characterized by a higher baryonic mass when comparing the clusters with larger density slopes. The correlation between the gas fraction and the inner slope indicates that the baryonic component affect the dark matter distribution in the central region of the cluster, which is in agreement with some other results.- Publication:
-
Ph.D. Thesis
- Pub Date:
- April 2014
- Bibcode:
- 2014PhDT.......435B
- Keywords:
-
- X-ray galaxy clusters;
- dark matter;
- intracluster gas.