This beautiful image shows the galaxy pair ARP 147.
X-ray and Optical Composite of ARP 147 Credit: X-ray: NASA/CXC/MIT/S.Rappaport et al, Optical: NASA/STScI
The two galaxies collided several hundred million years ago turning a once normal spiral galaxy into the spectacular ring we see today. Its elliptical partner survived the event with much less alteration to its structure.
The collision compressed much of the gas and dust in the spiral galaxy sparking an intense wave of star formation within it. This created a vast number of new stars, many of which would have been high mass. These used their stock of hydrogen ‘fuel’ within a few million years before ripping themselves apart in supernovae. Their remains formed neutron stars and black holes.
Black holes in particular release large amounts of x-ray radiation from the disk of material falling into them (their accretion disk). NASA’s Chandra telescope can detect this x-ray emission and in an x-ray image of the galaxy pair these black holes stick out like sore thumbs.
ARP 147 in X-rays Credit: NASA/CXC/MIT/S.Rappaport et al
The arc on the right-hand side are black holes within the former spiral. The bright blob in the center is believed to be a ...