Outbursts of the intermediate-mass black hole HLX-1: a wind-instability scenario
We model the intermediate-mass black hole HLX-1, using the Hubble Space Telescope, XMM–Newton and Swift. We quantify the relative contributions of a bluer component, function of X-ray irradiation, and a redder component, constant and likely coming from an old stellar population. We estimate a black...
| Main Authors: | , , , , , , , |
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| Format: | Journal Article |
| Published: |
Oxford University Press
2017
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| Online Access: | http://hdl.handle.net/20.500.11937/54899 |
| _version_ | 1848759491322970112 |
|---|---|
| author | Soria, Roberto Musaeva, A. Wu, K. Zampieri, L. Federle, S. Urquhart, Ryan van der Helm, E. Farrell, S. |
| author_facet | Soria, Roberto Musaeva, A. Wu, K. Zampieri, L. Federle, S. Urquhart, Ryan van der Helm, E. Farrell, S. |
| author_sort | Soria, Roberto |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | We model the intermediate-mass black hole HLX-1, using the Hubble Space Telescope, XMM–Newton and Swift. We quantify the relative contributions of a bluer component, function of X-ray irradiation, and a redder component, constant and likely coming from an old stellar population. We estimate a black hole mass
≈(2+2−1)×104M⊙
, a spin parameter a/M ≈ 0.9 for moderately face-on view and a peak outburst luminosity ≈0.3 times the Eddington luminosity. We discuss the discrepancy between the characteristic sizes inferred from the short X-ray time-scale (R ∼ a few 1011 cm) and from the optical emitter (
Rcosθ−−−−√≈2.2×1013
cm). One possibility is that the optical emitter is a circumbinary disc; however, we disfavour this scenario because it would require a very small donor star. A more plausible scenario is that the disc is large but only the inner annuli are involved in the X-ray outburst. We propose that the recurrent outbursts are caused by an accretion-rate oscillation driven by wind instability in the inner disc. We argue that the system has a long-term-average accretion rate of a few per cent Eddington, just below the upper limit of the low/hard state; a wind-driven oscillation can trigger transitions to the high/soft state, with a recurrence period ∼1 yr (much longer than the binary period, which we estimate as ∼10 d). The oscillation that dominated the system in the last decade is now damped such that the accretion rate no longer reaches the level required to trigger a transition. Finally, we highlight similarities between disc winds in HLX-1 and in the Galactic black hole V404 Cyg. |
| first_indexed | 2025-11-14T10:00:44Z |
| format | Journal Article |
| id | curtin-20.500.11937-54899 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T10:00:44Z |
| publishDate | 2017 |
| publisher | Oxford University Press |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-548992018-08-16T07:01:23Z Outbursts of the intermediate-mass black hole HLX-1: a wind-instability scenario Soria, Roberto Musaeva, A. Wu, K. Zampieri, L. Federle, S. Urquhart, Ryan van der Helm, E. Farrell, S. We model the intermediate-mass black hole HLX-1, using the Hubble Space Telescope, XMM–Newton and Swift. We quantify the relative contributions of a bluer component, function of X-ray irradiation, and a redder component, constant and likely coming from an old stellar population. We estimate a black hole mass ≈(2+2−1)×104M⊙ , a spin parameter a/M ≈ 0.9 for moderately face-on view and a peak outburst luminosity ≈0.3 times the Eddington luminosity. We discuss the discrepancy between the characteristic sizes inferred from the short X-ray time-scale (R ∼ a few 1011 cm) and from the optical emitter ( Rcosθ−−−−√≈2.2×1013 cm). One possibility is that the optical emitter is a circumbinary disc; however, we disfavour this scenario because it would require a very small donor star. A more plausible scenario is that the disc is large but only the inner annuli are involved in the X-ray outburst. We propose that the recurrent outbursts are caused by an accretion-rate oscillation driven by wind instability in the inner disc. We argue that the system has a long-term-average accretion rate of a few per cent Eddington, just below the upper limit of the low/hard state; a wind-driven oscillation can trigger transitions to the high/soft state, with a recurrence period ∼1 yr (much longer than the binary period, which we estimate as ∼10 d). The oscillation that dominated the system in the last decade is now damped such that the accretion rate no longer reaches the level required to trigger a transition. Finally, we highlight similarities between disc winds in HLX-1 and in the Galactic black hole V404 Cyg. 2017 Journal Article http://hdl.handle.net/20.500.11937/54899 10.1093/mnras/stx888 Oxford University Press fulltext |
| spellingShingle | Soria, Roberto Musaeva, A. Wu, K. Zampieri, L. Federle, S. Urquhart, Ryan van der Helm, E. Farrell, S. Outbursts of the intermediate-mass black hole HLX-1: a wind-instability scenario |
| title | Outbursts of the intermediate-mass black hole HLX-1: a wind-instability scenario |
| title_full | Outbursts of the intermediate-mass black hole HLX-1: a wind-instability scenario |
| title_fullStr | Outbursts of the intermediate-mass black hole HLX-1: a wind-instability scenario |
| title_full_unstemmed | Outbursts of the intermediate-mass black hole HLX-1: a wind-instability scenario |
| title_short | Outbursts of the intermediate-mass black hole HLX-1: a wind-instability scenario |
| title_sort | outbursts of the intermediate-mass black hole hlx-1: a wind-instability scenario |
| url | http://hdl.handle.net/20.500.11937/54899 |