These include active galactic nuclei, and quasars which are thought  to be the accretion disks of supermassive black holes, and also ultraluminous x-ray sources  thought to be from intermediate mass black holes.

这些包括活跃的星系核和类星体，它们被认为是超大质量黑洞的吸积盘，以及被认为来自中等质量黑洞的超亮X射线源。