The gas distribution in high-redshift clusters

• Main Author: Mirakhor, Mohammad Sabah Kader
• Published: University of Bristol 2016
• Subjects: 523.8
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.702455

In this study, we investigate the gas mass distribution for a sample of massive, high-red shift, galaxy clusters using Chandra X-ray data and some One Centimetre Receiver array Sunyaev-Zel'dovich effect data. We begin with an investigation of the gas mass distribution in the galaxy cluster MS 1054-0321, with redshift z = 0.83, using both X-ray and Sunyaev-Zel'dovich effect data. We then go on to investigate the gas mass distribution of five galaxy clusters, with redshifts between 0.54 and 0.90, using Chandra X-ray data. For cluster MS 1054-0321, we find that the X-ray and SZ gas mass fractions for the main component estimated from a single triaxial β-model are consistent with those estimated from the double triaxial , β-model within the same region. For the cluster sample, similarly, we find that the mean X-ray gas mass fraction within the θ2500 angular radius estimated from the single triaxial ,β-model is consistent with that estimated for the main components from the double triaxial ,β-model. The relative model-independence of the gas mass fraction measurements implies that our estimates are robust and reliable. The gas mass fractions within lh500 are on average about 35% below the cosmic value from the Planck analysis. However, we find that the mean gas mass fraction could approach the cosmic value within the θ200 angular radius, suggesting that the intracluster gas is more widely distributed than the dark matter. The X-ray gas mass fraction estimated for all secondary components is significantly lower than that estimated for the main components. Within the θ2500 radius, we estimate that the X-ray and SZ gas mass fractions for the main component of MS 1054-0321 might be systematically biased by the isothermal assumption by as much as +60% and +90%, respectively. For other clusters, we estimate that the isothermal assumption could bias our gas mass fraction measurements for the main components up to ± 15% within the cluster core, and as much as +70% or -50% within the cluster outskirts.