HST and Chandra image composite of recoiling black holes Credit:
X-ray: NASA/CXC/SAO/F. Civano et al. Optical: NASA/STScI   As we
try to extend our cosmic census of black holes, we find more and
more examples of bizarre behavior. The image above is a case in
point. This image is a composite of a galaxy merger seen in
visible light (from the Hubble Space Telescope, in brown) and in
X-rays (from the Chandra X-ray Observatory, in blue), obtained
as part of the large Cosmic Evolution Survey (a study of how
galaxies change with time and environment). The Hubble image
shows two bright unresolved sources near the center of this
merged galaxy, while the Chandra image shows associated X-ray
emission from hot gas in the vicinity of these sources. Detailed
study with the Very Large Telescope and the Magellan telescope
show that there is a large difference in speed between the two
optical sources of at least about three million miles an hour,
while Chandra finds evidence for fast flows of hot material in
the system. Astr