Into the heart of the pair of merging galaxies known as UGC 4211

Scientists using the Atacama Large Millimeter/submillimeter Array (ALMA) to look deep into the heart of the pair of merging galaxies known as UGC 4211 discovered two black holes growing side by side, just 750 light-years apart. This artist’s conception shows the late-stage galaxy merger and its two central black holes. The binary black holes are the closest together ever observed in multiple wavelengths.
Credit: ALMA (ESO/NAOJ/NRAO); M. Weiss (NRAO/AUI/NSF)