X-ray Properties of the Abell 644 Cluster of Galaxies

Abstract

We use new ASCA observations and archival ROSAT Position Sensitive Proportional Counter (PSPC) data to determine the X-ray spectral properties of the intracluster gas in Abell 644. From the overall spectrum, we determine the average gas temperature to be 8.64 (+0.67,-0.56) keV, and an abundance of 0.32 (+/-0.04) $Z_{\odot }$. The global ASCA and ROSAT spectra imply a cooling rate of 214 (+100,-91) $M_{\odot }$ yr${}^{-1}$. The PSPC X-ray surface brightness profile and the ASCA data suggest a somewhat higher cooling rate. We determine the gravitational mass and gas mass as a function of radius. The total gravitating mass within 1.2 Mpc is $6.2\times 10^{14}$ $M_{\odot }$, of which 20% is in the form of hot gas. There is a region of elevated temperature 1.5-5 arcmin to the west of the cluster center. The south-southwest region of the cluster also shows excess emission in the ROSAT PSPC X-ray image, aligned with the major axis of the optical cD galaxy in the center of the cluster. We argue that the cluster is undergoing or has recently undergone a minor merger. The combination of a fairly strong cooling flow and evidence for a merger make this cluster an interesting case to test the disruption of cooling flow in mergers.

26 pages LaTeX including 9 eps figures + 4 pages LaTeX tables (landscape); accepted to ApJ, uses aaspp4

References in corpus (4)

• The Temperature Structure of 30 Nearby Clusters Observed with ASCA. Similarity of Temperature Profiles
• An investigation of cooling flows and general cluster properties from an X-ray image deprojection analysis of 207 clusters of galaxies
• A ROSAT study of the cores of clusters of galaxies - I. Cooling flows in an X-ray flux-limited sample
• Measuring Molecular, Neutral Atomic, and Warm Ionized Galactic Gas Through X-Ray Absorption

Cited by in corpus (5)

• Models of the ICM with Heating and Cooling: Explaining the Global and Structural X-ray Properties of Clusters
• Distribution of dark and baryonic matter in clusters of galaxies
• The Heated Core of the Radio-Quiet Galaxy Cluster A644
• Supermodel Analysis of Galaxy Clusters
• Non-thermal X-ray Emission: An Alternative to Cluster Cooling Flows?