Viewed in visible light, the elliptical galaxy NGC 4261 looks positively sedate. But a new X-ray image reveals evidence of a violent past–a trail more than 50 light-years across and rife with black holes and neutron stars. The trail indicates that the galaxy collided with another galaxy a few billion years ago, says Lars Hernquist of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass.
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