The ultracompact nature of the black hole candidate X-ray binary 47 Tuc X9
47 Tuc X9 is a low-mass X-ray binary (LMXB) in the globular cluster 47 Tucanae, and was previously thought to be a cataclysmic variable. However, Miller-Jones et al. recently identified a radio counterpart to X9 (inferring a radio/X-ray luminosity ratio consistent with black hole LMXBs), and suggest...
| Main Authors: | , , , , , , , , , , , |
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| Format: | Journal Article |
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Oxford University Press
2017
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| Online Access: | http://hdl.handle.net/20.500.11937/62868 |
| _version_ | 1848760931646963712 |
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| author | Bahramian, A. Heinke, C. Tudor, Vlad Miller-Jones, James Bogdanov, S. Maccarone, T. Knigge, C. Sivakoff, G. Chomiuk, L. Strader, J. Garcia, J. Kallman, T. |
| author_facet | Bahramian, A. Heinke, C. Tudor, Vlad Miller-Jones, James Bogdanov, S. Maccarone, T. Knigge, C. Sivakoff, G. Chomiuk, L. Strader, J. Garcia, J. Kallman, T. |
| author_sort | Bahramian, A. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | 47 Tuc X9 is a low-mass X-ray binary (LMXB) in the globular cluster 47 Tucanae, and was previously thought to be a cataclysmic variable. However, Miller-Jones et al. recently identified a radio counterpart to X9 (inferring a radio/X-ray luminosity ratio consistent with black hole LMXBs), and suggested that the donor star might be a white dwarf. We report simultaneous observations of X9 performed by Chandra, NuSTAR and Australia Telescope Compact Array. We find a clear 28.18 ± 0.02-min periodic modulation in the Chandra data, which we identify as the orbital period, confirming this system as an ultracompact X-ray binary. Our X-ray spectral fitting provides evidence for photoionized gas having a high oxygen abundance in this system, which indicates a C/O white dwarf donor. We also identify reflection features in the hard X-ray spectrum, making X9 the faintest LMXB to show X-ray reflection. We detect an ~6.8-d modulation in the X-ray brightness by a factor of 10, in archival Chandra, Swiftand ROSAT data. The simultaneous radio/X-ray flux ratio is consistent with either a black hole primary or a neutron star primary, if the neutron star is a transitional millisecond pulsar. Considering the measured orbital period (with other evidence of a white dwarf donor), and the lack of transitional millisecond pulsar features in the X-ray light curve, we suggest that this could be the first ultracompact black hole X-ray binary identified in our Galaxy. |
| first_indexed | 2025-11-14T10:23:37Z |
| format | Journal Article |
| id | curtin-20.500.11937-62868 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T10:23:37Z |
| publishDate | 2017 |
| publisher | Oxford University Press |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-628682018-04-09T04:08:06Z The ultracompact nature of the black hole candidate X-ray binary 47 Tuc X9 Bahramian, A. Heinke, C. Tudor, Vlad Miller-Jones, James Bogdanov, S. Maccarone, T. Knigge, C. Sivakoff, G. Chomiuk, L. Strader, J. Garcia, J. Kallman, T. 47 Tuc X9 is a low-mass X-ray binary (LMXB) in the globular cluster 47 Tucanae, and was previously thought to be a cataclysmic variable. However, Miller-Jones et al. recently identified a radio counterpart to X9 (inferring a radio/X-ray luminosity ratio consistent with black hole LMXBs), and suggested that the donor star might be a white dwarf. We report simultaneous observations of X9 performed by Chandra, NuSTAR and Australia Telescope Compact Array. We find a clear 28.18 ± 0.02-min periodic modulation in the Chandra data, which we identify as the orbital period, confirming this system as an ultracompact X-ray binary. Our X-ray spectral fitting provides evidence for photoionized gas having a high oxygen abundance in this system, which indicates a C/O white dwarf donor. We also identify reflection features in the hard X-ray spectrum, making X9 the faintest LMXB to show X-ray reflection. We detect an ~6.8-d modulation in the X-ray brightness by a factor of 10, in archival Chandra, Swiftand ROSAT data. The simultaneous radio/X-ray flux ratio is consistent with either a black hole primary or a neutron star primary, if the neutron star is a transitional millisecond pulsar. Considering the measured orbital period (with other evidence of a white dwarf donor), and the lack of transitional millisecond pulsar features in the X-ray light curve, we suggest that this could be the first ultracompact black hole X-ray binary identified in our Galaxy. 2017 Journal Article http://hdl.handle.net/20.500.11937/62868 10.1093/mnras/stx166 Oxford University Press fulltext |
| spellingShingle | Bahramian, A. Heinke, C. Tudor, Vlad Miller-Jones, James Bogdanov, S. Maccarone, T. Knigge, C. Sivakoff, G. Chomiuk, L. Strader, J. Garcia, J. Kallman, T. The ultracompact nature of the black hole candidate X-ray binary 47 Tuc X9 |
| title | The ultracompact nature of the black hole candidate X-ray binary 47 Tuc X9 |
| title_full | The ultracompact nature of the black hole candidate X-ray binary 47 Tuc X9 |
| title_fullStr | The ultracompact nature of the black hole candidate X-ray binary 47 Tuc X9 |
| title_full_unstemmed | The ultracompact nature of the black hole candidate X-ray binary 47 Tuc X9 |
| title_short | The ultracompact nature of the black hole candidate X-ray binary 47 Tuc X9 |
| title_sort | ultracompact nature of the black hole candidate x-ray binary 47 tuc x9 |
| url | http://hdl.handle.net/20.500.11937/62868 |