M22

“If... then my old theory is completely toast,” says astrophysicist Steinn Sigurdsson of Pennsylvania State University. “This is a really nice piece of work.” Nice Nature paper coming out tomorrow by Jay Strader et al on a pair of flat spectrum ultra-faint radio sources in the core of M22. The sources are consistent with being ~ 20 solar mass black holes, accreting at a low rate from, well, something. Maybe... Best candidates yet in the Milky Way globulars. M22 has a somewhat unusual structure (massive fluffy core) in a way that several authors have suggested might be a signature of black…