A Chandra Study of the Complex Structure in the Core of 2A 0335+096

Abstract

We present a Chandra observation of the central (r < 200 kpc) region of the cluster of galaxies 2A 0335+096, rich in interesting phenomena. On large scales (r > 40 kpc), the X-ray surface brightness is symmetric and slightly elliptical. The cluster has a cool, dense core; the radial temperature gradient varies with position angle. The radial metallicity profile shows a pronounced central drop and an off-center peak. Similarly to many clusters with dense cores, 2A 0335+096 hosts a cold front at r ≈ 40 kpc south of the center. The gas pressure across the front is discontinuous by a factor AP = 1.6 ± 0.3, indicating that the cool core is moving with respect to the ambient gas with a Mach number M ≈ 0.75 ± 0.2. The central dense region inside the cold front shows an unusual X-ray morphology, which consists of a number of X-ray blobs and/or filaments on scales 3 kpc, along with two prominent X-ray cavities. The X-ray blobs are not correlated with either the optical line emission (Hα+[N II]), member galaxies, or radio emission. The deprojected temperature of the dense blobs is consistent with that of the less dense ambient gas, so these gas phases do not appear to be in thermal pressure equilibrium. An interesting possibility is a significant, unseen nonthermal pressure component in the interblob gas, possibly arising from the activity of the central active galactic nucleus (AGN). We discuss two models for the origin of the gas blobs—hydrodynamic instabilities caused by the observed motion of the gas core and "bubbling" of the core caused by multiple outbursts of the central AGN.