1RXS J004704.8-204743: A ULX in the Thermal Dominant State

The nature of ultraluminous X-ray sources (ULXs) is unknown, and even their connection to Galactic black hole binaries (BHBs) is unclear. The thermal dominant state is the best understood emission state in BHBs but is rarely seen in ULXs. Identification of ULXs in the thermal dominant state will enable us to compare them with Galactic BHBs directly and place constraints on their mass and spin. A previous XMM observation of NGC 247 indicates that 1RXS J004704.8-204743 is probably in the thermal dominant state. We request a 28 ks XMM observation of the source to obtain a better spectrum and determine its emission state. If the X-ray spectrum is confirmed to be dominated by thermal radiation from an accretion disk, the source may contain a black hole of about a thousand solar masses.