ChandraImaging of the X‐Ray Core of the Virgo Cluster

Abstract

We report subarcsecond X-ray imaging spectroscopy of M87 and the core of the Virgo Cluster with the Chandra X-Ray Observatory. The X-ray morphology shows structure on arcsecond (~100 pc) to 10' (~50 kpc) scales, the most prominent feature being an arc running from the east, across the central region of M87, and off to the southwest. A ridge in the radio map, ending in an ear-shaped structure, follows the arc to the east. Depressions in the X-ray surface brightness correspond to the inner radio lobes, and there is no evidence of shock-heated gas surrounding them. There are also at least two approximately circular (centered near the nucleus) edges in the X-ray brightness distribution, the radii of which are slightly larger than the nuclear distances of the inner radio lobes and intermediate radio ridges. We speculate that these discontinuities may be spherical pulses or fronts driven by the same jet activity as is responsible for the radio structure; such pulses are found in recent numerical simulations. All these results provide good evidence that the nuclear activity affects the intracluster medium. We present a temperature map of the intracluster medium and obtain the temperature, pressure, and cooling time as a function of nuclear distance for the arcs and the ambient intracluster medium. We show that the gas in the arcs is cooler than, and probably overpressured with respect to, the ambient intracluster medium. The metal abundances of the cooler gas in the arc are somewhat enhanced relative to the ambient intracluster medium, favoring a buoyant plume origin for the X-ray arc, in which ambient gas near the nucleus is entrained by buoyant radio plasma and carried to larger nuclear distances. The gas within the inner front (nuclear distance 3.5 kpc 45'') is at least a two-temperature plasma, with the cool component at 1 keV. This cool region is concentrated to the north of the nucleus and is strongly correlated with the H?+[N II] emission line distribution.