Now, you get another view with the x-ray light collected with the Chandra X-Ray Observatory. The ring is seen again with many discrete sources. In fact, they are so bright that they must be stellar-mass black holes.
These are the remnants of the very biggest stars that have died off already, leaving black holes behind after an energetic supernova. If such a star had a close enough companion star, then the black hole left behind is pulling material off of that star onto itself, releasing massive amounts of energy in the form of x-rays from the disk surrounding the black hole.
The galaxy on the left is not unperturbed either. It has a bright x-ray source in the center, indicating that there is some activity going on there as well. In the most likely scenario, gas that has been stirred up by the collision has fallen towards a supermassive black hole that resides in the center of the galaxy. Material rushing around as it "swirls down the drain" will also give off x-rays here.
The activity is not obvious from the optical picture alone, so the addition of information from another part of the electromagnetic spectrum is crucial to seeing the whole picture. Though no stars are colliding in this scenario, gas does collide, creating stars and all the impressive processes that come with them, changing the evolution of these galaxies forever.
Image: Composite of Hubble and Chandra images of Arp 147, as well as each telescope's contribution shown individually. Credit: X-ray: NASA/CXC/MIT/S.Rappaport et al, Optical: NASA/STScI