期刊
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN
卷 61, 期 4, 页码 769-776出版社
OXFORD UNIV PRESS
DOI: 10.1093/pasj/61.4.769
关键词
accretion, accretion disks; black hole physics; hydrodynamics; radiative transfer
资金
- Cybermedia Center Osaka University
- Ministry of Education, Culture, Sports, Science and Technology (MEXT) [20740115]
- MEXT [19340044, 20340040]
- The Next Generation of Physics, Spun from Diversity and Emergence from MEXT
- Grants-in-Aid for Scientific Research [20340040, 20740115, 19340044] Funding Source: KAKEN
Supercritical accretion flows inevitably produce radiation-pressure driven outflows, which Compton up-scatter soft photons from the underlying accretion flow, thereby making hard emission. We performed two-dimensional radiation hydrodynamic simulations of supercritical accretion flows and outflows, while incorporating such Compton scattering effects, and demonstrated that there appears a new hard spectral state at higher photon luminosities than that of the slim-disk state. In this state, as the photon luminosity increases, the photon index decreases and the fraction of the hard emission increases. The Compton v-parameter is on the order of unity (and thus the photon index will be similar to 2) when the apparent photon luminosity is similar to 30 L-E (with L-E being the Eddington luminosity) for nearly face-on sources. This explains the observed spectral hardening of the ULX NGC 1313 X-2 in its brightening phase, and thus supports the model of supercritical accretion onto stellar-mass black holes in this ULX.
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