Here's
wide-field composite view of our neighboring Andromeda Galaxy. It was taken at the Warner and Swansey Observatory on Kitt Peak in Arizon, with additional detail from astrophotographer Vicent Peris. But the inset is X-ray data data from NASA's Chandra X-ray Observatory and shows black hole candidates. A team of researchers looking over 13 years worth of Chandra data found 26 of them to add to nine already known.
There are more black hole candidates in the central bulge of Andromeda than there are in the central area of the Milky Way. Each one represents the
death of a massive star.
(We call them black hole candidates because although they appear to be black holes, there isn't enough data for cautious astronomers to confidently proclaim them to be black holes.)
Credits: X-ray: NASA/CXC/SAO/R. Barnard, Z. Lee et al.; Optical: NOAO/AURA/NSF/REU Program/B. Schoening, V. Harvey and Descubre Foundation/CAHA/OAUV/DSA/V. Peris