Hard and soft spectral states of ULXs
dc.contributor.author | Soria, Roberto | |
dc.date.accessioned | 2017-01-30T14:37:13Z | |
dc.date.available | 2017-01-30T14:37:13Z | |
dc.date.created | 2012-03-23T01:19:57Z | |
dc.date.issued | 2011 | |
dc.identifier.citation | Soria, R. 2011. Hard and soft spectral states of ULXs. Astronomische Nachrichten. 332 (4): pp. 330-336. | |
dc.identifier.uri | http://hdl.handle.net/20.500.11937/39815 | |
dc.identifier.doi | 10.1002/asna.201011493 | |
dc.description.abstract |
I discuss some differences between the observed spectral states of ultraluminous X-ray sources (ULXs) and the canonical scheme of spectral states defined in Galactic black holes. The standard interpretation of ULXs with a curved spectrum, or a moderately steep power-law with soft excess and high-energy downturn, is that they are an extension of the very high state, up to luminosities ≈1–3L Edd. Two competing models are Comptonization in a warm corona, and slim disk; I suggest bulk motion Comptonization in the radiatively-driven outflow as another possibility. The interpretation of ULXs with a hard power-law spectrum is more problematic. Some of them remain in that state over a large range of luminosities; others switch directly to a curved state without going through a canonical high/soft state. I suggest that those ULXs are in a high/hard state not seen in Galactic black holes; that state may overlap with the low/hard state at lower accretion rates, and extend all the way to Eddington accretion rates. If some black holes can reach Eddington accretion rates without switching to a standard-disk-dominated state, it is also possible that they never quench their steady jets. | |
dc.publisher | Wiley - V C H Verlag GmbH & Co. KGaA | |
dc.title | Hard and soft spectral states of ULXs | |
dc.type | Journal Article | |
dcterms.source.volume | 332 | |
dcterms.source.number | 2 | |
dcterms.source.startPage | 330 | |
dcterms.source.endPage | 336 | |
dcterms.source.issn | 1521-3994 | |
dcterms.source.title | Astronomische Nachrichten | |
curtin.department | Curtin Institute of Radio Astronomy | |
curtin.accessStatus | Open access via publisher |