Chandra Observations of Nuclear Outflows in the Elliptical Galaxy   NGC4552 in the Virgo Cluster
  We use a 54.4 ks Chandra observation to study nuclear outflow activity in NGC4552 (M89), an elliptical galaxy in the Virgo Cluster. Chandra images in the 0.5-2 keV band show two ring-like features ~1.7 kpc in diameter in the core of NGC4552, as reported previously by Filho et al. We use spherically symmetric point explosion shock models to argue that the shape of the surface brightness profile across the rims of the rings and the temperature of hot gas in the rings are consistent with a Mach 1.7 shock carrying mean mechanical power L_shock ~ 3 x 10^{41} ergs/s produced by a ~1.4 x 10^{55} ergs nuclear outburst \~1 - 2 Myr ago. We find the gas temperature in the central ~100 pc of the galaxy to be 1.0 +/- 0.2 keV, hotter than elsewhere in the galaxy, suggesting that we may be observing directly the reheating of the galaxy ISM by the outburst. 
M. Machacek, P.E.J. Nulsen, C. Jones, W.R. Forman (CfA)