Supermassive black holes in all galaxies? Maybe not

View larger. | In recent decades, we’ve come to understand most large galaxies as having central supermassive black holes. Our own galaxy, the Milky Way, has one. And the similarly sized galaxy NGC 6278, on the left, has one. But a new study of 1,600 galaxies suggests many of the smaller ones – like PGC 03620 (right) – don’t contain supermassive black holes. X-rays image via NASA/CXC/SAO/F. Zou et al. Optical image via SDSS. Image processing via NASA/CXC/SAO/N. Wolk.

• Scientists might have...