Supermassive black holes may grow quietly, without galactic violence

The reigning picture said supermassive black holes grow in violent galaxy collisions that also build a central bulge. A new survey of 2,435 disk galaxies, including 546 bulgeless ones that never had a major merger, finds black holes just as massive as expected, scaling with the whole galaxy rather than the bulge. The quiet, slow lane may be how black holes like our own grew up.