Conditions favorable for gravitational wave-emitting mergers of massive black holes exist in the outer gas disks of big spiral galaxies, according to a study by Rochester Institute of Technology astronomer Sukanya Chakrabarti and co-authors. This Hubble image shows the spiral galaxy Messier 83. Image credit: NASA / ESA / Hubble Heritage Team / STScI / AURA / W. Blair, STScI & JHU / Carnegie Institution of Washington / Las Campanas Observatory...
