Three spectral states of the disk X-ray emission of the black hole candidate 4U1630-47

Recent RXTE observations have identified a very high state for several black hole candidates. Kubota et al. (2001, 2004) reported that this state can be accounted for by the inverse Compton scattering and slim disk emission. This idea is important for the purpose of obtaining a unified view of disk emission around black holes, but the sample is still poor. In addition, it has not been confirmed that the idea can be effectively applied to black hole binaries that repeat outbursts. For this reason, we analyzed the black hole candidate 4U1630-47, which is known to exhibit X-ray outbursts with a period of about 650 days, and we found it to be in a very high state in the outburst of 1998. We also found a very high state in the outburst of 1996. By considering inverse Compton scattering and slim disk emission, we found that these two very high states can be accounted as proposal by Kubota et al. It is found that 4U1630-47 is the third to exhibit three states. Three states are thought to be common among black hole binaries.