Astronomy and Astrophysics – Astrophysics
Scientific paper
1996-04-03
Astronomy and Astrophysics
Astrophysics
gzipped tar file of 26 PostScript pages, including 2 figures, 7 tables. Also available at http://www.astr.ua.edu/preprints/w
Scientific paper
10.1086/177437
We have analyzed X-ray spectra from six galaxy clusters which contain cooling flows: A85, A478, A1795, A2142, A2147, & A2199. The X-ray spectra were taken with the HEAO1-A2 Medium and High Energy Detectors and the Einstein Solid State Spectrometer. For each cluster, we simultaneously fit the spectra from these three detectors with models incorporating one or more emission components comprised of either thermal or cooling flow models. Five of the clusters (all but A2142) are better fit by a multi-component model (a cooling flow plus one or two thermal components or a two thermal component model) than by isothermal models. In four of the clusters (A85, A1795, A2147, & A2199), we find evidence for cool gas outside of the canonical cooling flow region. These latter four clusters can be characterized by three temperature components: a temperature inversion in the central region, a hotter region with an emission-weighted temperature which is higher than that of an isothermal model fit to the entire cluster, and a cooler region with an emission-weighted temperature of ~1 keV. The cool component outside the cooling flow region has a large minimum emission measure which we attribute, in part, to diffuse cool gas in the outer cluster atmosphere. If at least some of the cool exterior gas is virialized, this would imply a radially decreasing temperature profile. Together with the density profiles we have found, this leads to a baryon fraction in gas which increases with radius and is larger than that for an isothermal cluster atmosphere. Consequently, if clusters of galaxies trace the mass distribution in the Universe, the gas mass fraction we have calculated for an isothermal gas (which is ~15%) together with the nominal galaxy contribution (~5%) gives a baryon fraction of ~20%. Using the upper limit to the baryon density derived from Big
Henriksen Mark J.
White III Raymond E.
No associations
LandOfFree
Non-isothermal X-ray Emitting Gas in Clusters of Galaxies 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 Non-isothermal X-ray Emitting Gas in Clusters of Galaxies, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Non-isothermal X-ray Emitting Gas in Clusters of Galaxies will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-75045