NGC 5195 in M51: Feedback `Burps' after a Massive Meal?
  We describe a double-arc-like X-ray structure lying ~15-30" (~0.8-1.7 kpc) south of the NGC 5195 nucleus visible in the merged exposures of long Chandra pointings of M51. The curvature and orientation of the arcs argues for a nuclear origin. The arcs are radially separated by ~15" (~1$ kpc), but are rotated relative to each other by ~30 deg. From an archival image, we find a slender Halpha-emitting region just outside the outer edge of the outer X-ray arc, suggesting that the X-ray-emitting gas plowed up and displaced the Halpha-emitting material from the galaxy core. Star formation may have commenced in that arc. Halpha emission is present at the inner arc, but appears more complex in structure. In contrast to an explosion expected to be azimuthally symmetric, the X-ray arcs suggest a focused outflow. We interpret the arcs as episodic outbursts from the central super-massive black hole (SMBH). We conclude that NGC 5195 represents the nearest galaxy exhibiting on-going, large-scale outflows of gas, in particular, two episodes of a focused outburst of the SMBH. The arcs represent a clear demonstration of feedback. 
Eric M. Schlegel, Christine Jones, Marie Machacek, Laura D. Vega
astro-ph.GA