An X-Ray-Selected Sample of Candidate Black Holes in Dwarf Galaxies
We present a sample of hard X-ray-selected candidate black holes (BHs) in 19 dwarf galaxies. BH candidates are identified by cross-matching a parent sample of ~44,000 local dwarf galaxies (M* = 3 × 10 9 M☉, z < 0.055) with the Chandra Source Catalog and subsequently analyzing the original X-ray d...
| Main Authors: | , , , , |
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| Format: | Journal Article |
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Institute of Physics Publishing
2015
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| Online Access: | http://hdl.handle.net/20.500.11937/52411 |
| _version_ | 1848758919991656448 |
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| author | Lemons, S. Reines, A. Plotkin, Richard Gallo, E. Greene, J. |
| author_facet | Lemons, S. Reines, A. Plotkin, Richard Gallo, E. Greene, J. |
| author_sort | Lemons, S. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | We present a sample of hard X-ray-selected candidate black holes (BHs) in 19 dwarf galaxies. BH candidates are identified by cross-matching a parent sample of ~44,000 local dwarf galaxies (M* = 3 × 10 9 M☉, z < 0.055) with the Chandra Source Catalog and subsequently analyzing the original X-ray data products for matched sources. Of the 19 dwarf galaxies in our sample, eight have X-ray detections reported here for the first time. We find a total of 43 point-like hard X-ray sources with individual luminosities L2-10 keV ~ 10 37 - 10 40 erg s-1. Hard X-ray luminosities in this range can be attained by stellar-mass X-ray binaries (XRBs) and by massive BHs accreting at low Eddington ratio. We place an upper limit of 53% (10/19) on the fraction of galaxies in our sample hosting a detectable hard X-ray source consistent with the optical nucleus, although the galaxy center is poorly defined in many of our objects. We also find that 42% (8/19) of the galaxies in our sample exhibit statistically significant enhanced hard X-ray emission relative to the expected galaxy-wide contribution from low-mass and high-mass XRBs, based on the [data] star formation rate relation defined by more massive and luminous systems. For the majority of these X-ray-enhanced dwarf galaxies, the excess emission is consistent with (but not necessarily due to) a nuclear X-ray source. Follow-up observations are necessary to distinguish between stellar-mass XRBs and active galactic nuclei powered by more massive BHs. In any case, our results support the notion that X-ray-emitting BHs in low-mass dwarf galaxies may have had an appreciable impact on reionization in the early universe. |
| first_indexed | 2025-11-14T09:51:39Z |
| format | Journal Article |
| id | curtin-20.500.11937-52411 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T09:51:39Z |
| publishDate | 2015 |
| publisher | Institute of Physics Publishing |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-524112017-09-13T15:48:31Z An X-Ray-Selected Sample of Candidate Black Holes in Dwarf Galaxies Lemons, S. Reines, A. Plotkin, Richard Gallo, E. Greene, J. We present a sample of hard X-ray-selected candidate black holes (BHs) in 19 dwarf galaxies. BH candidates are identified by cross-matching a parent sample of ~44,000 local dwarf galaxies (M* = 3 × 10 9 M☉, z < 0.055) with the Chandra Source Catalog and subsequently analyzing the original X-ray data products for matched sources. Of the 19 dwarf galaxies in our sample, eight have X-ray detections reported here for the first time. We find a total of 43 point-like hard X-ray sources with individual luminosities L2-10 keV ~ 10 37 - 10 40 erg s-1. Hard X-ray luminosities in this range can be attained by stellar-mass X-ray binaries (XRBs) and by massive BHs accreting at low Eddington ratio. We place an upper limit of 53% (10/19) on the fraction of galaxies in our sample hosting a detectable hard X-ray source consistent with the optical nucleus, although the galaxy center is poorly defined in many of our objects. We also find that 42% (8/19) of the galaxies in our sample exhibit statistically significant enhanced hard X-ray emission relative to the expected galaxy-wide contribution from low-mass and high-mass XRBs, based on the [data] star formation rate relation defined by more massive and luminous systems. For the majority of these X-ray-enhanced dwarf galaxies, the excess emission is consistent with (but not necessarily due to) a nuclear X-ray source. Follow-up observations are necessary to distinguish between stellar-mass XRBs and active galactic nuclei powered by more massive BHs. In any case, our results support the notion that X-ray-emitting BHs in low-mass dwarf galaxies may have had an appreciable impact on reionization in the early universe. 2015 Journal Article http://hdl.handle.net/20.500.11937/52411 10.1088/0004-637X/805/1/12 Institute of Physics Publishing fulltext |
| spellingShingle | Lemons, S. Reines, A. Plotkin, Richard Gallo, E. Greene, J. An X-Ray-Selected Sample of Candidate Black Holes in Dwarf Galaxies |
| title | An X-Ray-Selected Sample of Candidate Black Holes in Dwarf Galaxies |
| title_full | An X-Ray-Selected Sample of Candidate Black Holes in Dwarf Galaxies |
| title_fullStr | An X-Ray-Selected Sample of Candidate Black Holes in Dwarf Galaxies |
| title_full_unstemmed | An X-Ray-Selected Sample of Candidate Black Holes in Dwarf Galaxies |
| title_short | An X-Ray-Selected Sample of Candidate Black Holes in Dwarf Galaxies |
| title_sort | x-ray-selected sample of candidate black holes in dwarf galaxies |
| url | http://hdl.handle.net/20.500.11937/52411 |