The collision process of two galaxies takes millions of years to mix the ingredients like stars slowly. This galactic Goulash then appears as a gorgeous interstellar stew filled with bright X-ray sources.
In 2017, NASA’s Chandra X-ray space telescope captured the intriguing image of such galactic Goulash, i.e., interacting galaxies, collectively named Arp 299. The telescope detected an unusually high number of bright X-ray sources in Arp 299. Of the 25 X-ray sources seen in the galactic mix, 14 are categorized as ultraluminous X-ray sources (ULXs) for their powerful X-ray emissions.
This composite image of Arp 299 contains X-ray data from Chandra (pink), higher-energy X-ray data from NuSTAR (purple), and optical data from the Hubble Space Telescope (white and faint brown). Arp 299 also emits copious amounts of infrared light that have been detected by observatories such as the Spitzer Space Telescope.