Outer Regions of the Cluster Gaseous Atmospheres

Details Outer Regions of the Cluster Gaseous Atmospheres Outer Regions of the Cluster Gaseous Atmospheres

1999-05-17

arxiv.org/abs/astro-ph/9905200v1

Astronomy and Astrophysics

Astrophysics

ApJ in press, submitted 11/30/98

Scientific paper

10.1086/307876

We present a systematic study of the hot gas distribution in the outer regions of regular clusters using ROSAT PSPC data. Outside the cooling flow region, the beta-model describes the observed surface brightness closely, but not precisely. Between 0.3 and 1 virial radii, the profiles are characterized by a power law with slope, expressed in terms of the beta parameter, in the range beta=0.65 to 0.85. The values of beta in this range of radii are typically larger by ~0.05 than those derived from the global fit. There is a mild trend for the slope to increase with temperature, from ~0.68 for 3 keV clusters to ~0.8 for 10 keV clusters; however, even at high temperatures there are clusters with flat gas profiles, 0.7. Our values of beta at large radius are systematically higher, and the trend of beta with temperature is weaker than was previously found; the most likely explanation is that earlier studies were affected by an incomplete exclusion of the central cooling flow regions. For our regular clusters, the gas distribution at large radii is quite close to spherically symmetric and this is shown not to be an artifact of the sample selection. The gas density profiles are very similar when compared in the units of cluster virial radius. The radius of fixed mean gas overdensity 1000 (corresponding to the dark matter overdensity 200 for Omega=0.2) shows a tight correlation with temperature, R~T**0.5, as expected from the virial theorem for clusters with the universal gas fraction. At a given temperature, the rms scatter of the gas overdensity radius is only ~7% which translates into a 20% scatter of the gas mass fraction, including statistical scatter due to measurement uncertainties.

Affiliated with

Also associated with

No associations

Rating

Outer Regions of the Cluster Gaseous Atmospheres 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 Outer Regions of the Cluster Gaseous Atmospheres, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Outer Regions of the Cluster Gaseous Atmospheres will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-32429