Sagittarius A*

…Andreas Nygard says, a recent paper in the Monthly Notices of the Royal Astronomical Society by Valentina Crespi and her collaborators argues that Sagittarius A star, which is a black hole at the center of our galaxy, could in principle be a horizonless self-gravitating core of fermionic dark matter, rather than a supermassive black hole.…

…In fact, whether SAG A star is spinning at all is unknown, but given that everything in the universe spins, planets, stars, galaxies, physicists are pretty confident that it is.…

…While researchers know a lot about this black hole, where it is, how far away it is, its likely mass, and so on, how much its spinning has been hard to pin down.…