IRAS 13224-3809

IRAS 13224-3809 is a Seyfert galaxy on the order of a billion light-years' distant. Its X-ray emission shows striking variability and its supermassive black hole (SMBH) has been studied using reverberation mapping, yielding estimates of the SMBH size and mass. One mass determination was 1.9×10⁶ solar masses, corresponding to a Schwarzschild radius of 8 solar radii, which should be the same order-of-magnitude as the radius of its event horizon (any such difference being due to rotation).