Black hole mass estimates from soft X-ray spectra
In the absence of direct kinematic measurements, the mass of an accreting black hole is sometimes inferred from the X-ray spectral parameters of its accretion disk; specifically, from the temperature and normalization of a disk-blackbody model fit. Suitable corrections have to be introduced when the...
| Main Authors: | , |
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| Format: | Journal Article |
| Published: |
Pergamon
2008
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| Online Access: | http://hdl.handle.net/20.500.11937/20083 |
| _version_ | 1848750209702559744 |
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| author | Soria, Roberto Kuncic, Z. |
| author_facet | Soria, Roberto Kuncic, Z. |
| author_sort | Soria, Roberto |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | In the absence of direct kinematic measurements, the mass of an accreting black hole is sometimes inferred from the X-ray spectral parameters of its accretion disk; specifically, from the temperature and normalization of a disk-blackbody model fit. Suitable corrections have to be introduced when the accretion rate approaches or exceeds the Eddington limit. We summarize phenomenological models that can explain the very high state, with apparently higher disk temperatures and lower inner-disk radii. Conversely, ultraluminous X-ray sources often contain cooler disks with large characteristic radii. We introduce another phenomenological model for this accretion state. We argue that a standard disk dominates the radiative output for radii larger than a characteristic transition radius View the MathML sourceRc~m˙×RISCO, where View the MathML sourcem˙ is the accretion rate in Eddington units and RISCO is the innermost stable orbit. For RISCO < R < Rc, most of the accretion power is released via non-thermal processes. We predict the location of such sources in a luminosity–temperature plot. We conclude that BHs with masses ~50–100M⊙ accreting at View the MathML sourcem˙~10–20 may explain the X-ray properties of many ULXs. |
| first_indexed | 2025-11-14T07:33:12Z |
| format | Journal Article |
| id | curtin-20.500.11937-20083 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T07:33:12Z |
| publishDate | 2008 |
| publisher | Pergamon |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-200832017-09-13T13:50:23Z Black hole mass estimates from soft X-ray spectra Soria, Roberto Kuncic, Z. In the absence of direct kinematic measurements, the mass of an accreting black hole is sometimes inferred from the X-ray spectral parameters of its accretion disk; specifically, from the temperature and normalization of a disk-blackbody model fit. Suitable corrections have to be introduced when the accretion rate approaches or exceeds the Eddington limit. We summarize phenomenological models that can explain the very high state, with apparently higher disk temperatures and lower inner-disk radii. Conversely, ultraluminous X-ray sources often contain cooler disks with large characteristic radii. We introduce another phenomenological model for this accretion state. We argue that a standard disk dominates the radiative output for radii larger than a characteristic transition radius View the MathML sourceRc~m˙×RISCO, where View the MathML sourcem˙ is the accretion rate in Eddington units and RISCO is the innermost stable orbit. For RISCO < R < Rc, most of the accretion power is released via non-thermal processes. We predict the location of such sources in a luminosity–temperature plot. We conclude that BHs with masses ~50–100M⊙ accreting at View the MathML sourcem˙~10–20 may explain the X-ray properties of many ULXs. 2008 Journal Article http://hdl.handle.net/20.500.11937/20083 10.1016/j.asr.2007.03.099 Pergamon fulltext |
| spellingShingle | Soria, Roberto Kuncic, Z. Black hole mass estimates from soft X-ray spectra |
| title | Black hole mass estimates from soft X-ray spectra |
| title_full | Black hole mass estimates from soft X-ray spectra |
| title_fullStr | Black hole mass estimates from soft X-ray spectra |
| title_full_unstemmed | Black hole mass estimates from soft X-ray spectra |
| title_short | Black hole mass estimates from soft X-ray spectra |
| title_sort | black hole mass estimates from soft x-ray spectra |
| url | http://hdl.handle.net/20.500.11937/20083 |