Quasi-simultaneous radio and X-ray observations of Aql X-1: Probing low luminosities
© 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society Aql X-1 is one of the best-studied neutron star low-mass X-ray binaries. It was previously targeted using quasi-simultaneous radio and X-ray observations during at least seven different accretion ou...
| Main Authors: | , , , , , , , , , , |
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| Format: | Journal Article |
| Language: | English |
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OXFORD UNIV PRESS
2020
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| Subjects: | |
| Online Access: | http://purl.org/au-research/grants/arc/FT140101082 http://hdl.handle.net/20.500.11937/80104 |
| _version_ | 1848764162955542528 |
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| author | Gusinskaia, N.V. Hessels, J.W.T. Degenaar, N. Deller, A.T. Miller-Jones, James Archibald, A.M. Heinke, C.O. Moldón, J. Patruno, A. Tomsick, J.A. Wijnands, R. |
| author_facet | Gusinskaia, N.V. Hessels, J.W.T. Degenaar, N. Deller, A.T. Miller-Jones, James Archibald, A.M. Heinke, C.O. Moldón, J. Patruno, A. Tomsick, J.A. Wijnands, R. |
| author_sort | Gusinskaia, N.V. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | © 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society Aql X-1 is one of the best-studied neutron star low-mass X-ray binaries. It was previously targeted using quasi-simultaneous radio and X-ray observations during at least seven different accretion outbursts. Such observations allow us to probe the interplay between accretion inflow (X-ray) and jet outflow (radio). Thus far, these combined observations have only covered one order of magnitude in radio and X-ray luminosity range; this means that any potential radio-X-ray luminosity correlation, LR ∝ LXβ, is not well constrained (β ≈ 0.4-0.9, based on various studies) or understood. Here we present quasi-simultaneous Very Large Array and Swift-XRT observations of Aql X-1's 2016 outburst, with which we probe one order of magnitude fainter in radio and X-ray luminosity compared to previous studies (6 × 1034 erg s−1 < LX <3 × 1035 erg s−1, i.e. the intermediate to low-luminosity regime between outburst peak and quiescence). The resulting radio non-detections indicate that Aql X-1's radio emission decays more rapidly at low X-ray luminosities than previously assumed - at least during the 2016 outburst. Assuming similar behaviour between outbursts, and combining all available data in the hard X-ray state, this can be modelled as a steep β =1.17+−003021 power-law index or as a sharp radio cut-off at LX ≲ 5 × 1035 erg s−1 (given our deep radio upper limits at X-ray luminosities below this value). We discuss these results in the context of other similar studies. |
| first_indexed | 2025-11-14T11:14:59Z |
| format | Journal Article |
| id | curtin-20.500.11937-80104 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| language | English |
| last_indexed | 2025-11-14T11:14:59Z |
| publishDate | 2020 |
| publisher | OXFORD UNIV PRESS |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-801042020-07-29T09:25:06Z Quasi-simultaneous radio and X-ray observations of Aql X-1: Probing low luminosities Gusinskaia, N.V. Hessels, J.W.T. Degenaar, N. Deller, A.T. Miller-Jones, James Archibald, A.M. Heinke, C.O. Moldón, J. Patruno, A. Tomsick, J.A. Wijnands, R. Science & Technology Physical Sciences Astronomy & Astrophysics stars: neutron X-rays: binaries NEUTRON-STAR BLACK-HOLES HARD STATE ACCRETION BINARY PULSATIONS POWER JETS EMISSION FLOWS © 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society Aql X-1 is one of the best-studied neutron star low-mass X-ray binaries. It was previously targeted using quasi-simultaneous radio and X-ray observations during at least seven different accretion outbursts. Such observations allow us to probe the interplay between accretion inflow (X-ray) and jet outflow (radio). Thus far, these combined observations have only covered one order of magnitude in radio and X-ray luminosity range; this means that any potential radio-X-ray luminosity correlation, LR ∝ LXβ, is not well constrained (β ≈ 0.4-0.9, based on various studies) or understood. Here we present quasi-simultaneous Very Large Array and Swift-XRT observations of Aql X-1's 2016 outburst, with which we probe one order of magnitude fainter in radio and X-ray luminosity compared to previous studies (6 × 1034 erg s−1 < LX <3 × 1035 erg s−1, i.e. the intermediate to low-luminosity regime between outburst peak and quiescence). The resulting radio non-detections indicate that Aql X-1's radio emission decays more rapidly at low X-ray luminosities than previously assumed - at least during the 2016 outburst. Assuming similar behaviour between outbursts, and combining all available data in the hard X-ray state, this can be modelled as a steep β =1.17+−003021 power-law index or as a sharp radio cut-off at LX ≲ 5 × 1035 erg s−1 (given our deep radio upper limits at X-ray luminosities below this value). We discuss these results in the context of other similar studies. 2020 Journal Article http://hdl.handle.net/20.500.11937/80104 10.1093/mnras/stz3420 English http://purl.org/au-research/grants/arc/FT140101082 OXFORD UNIV PRESS fulltext |
| spellingShingle | Science & Technology Physical Sciences Astronomy & Astrophysics stars: neutron X-rays: binaries NEUTRON-STAR BLACK-HOLES HARD STATE ACCRETION BINARY PULSATIONS POWER JETS EMISSION FLOWS Gusinskaia, N.V. Hessels, J.W.T. Degenaar, N. Deller, A.T. Miller-Jones, James Archibald, A.M. Heinke, C.O. Moldón, J. Patruno, A. Tomsick, J.A. Wijnands, R. Quasi-simultaneous radio and X-ray observations of Aql X-1: Probing low luminosities |
| title | Quasi-simultaneous radio and X-ray observations of Aql X-1: Probing low luminosities |
| title_full | Quasi-simultaneous radio and X-ray observations of Aql X-1: Probing low luminosities |
| title_fullStr | Quasi-simultaneous radio and X-ray observations of Aql X-1: Probing low luminosities |
| title_full_unstemmed | Quasi-simultaneous radio and X-ray observations of Aql X-1: Probing low luminosities |
| title_short | Quasi-simultaneous radio and X-ray observations of Aql X-1: Probing low luminosities |
| title_sort | quasi-simultaneous radio and x-ray observations of aql x-1: probing low luminosities |
| topic | Science & Technology Physical Sciences Astronomy & Astrophysics stars: neutron X-rays: binaries NEUTRON-STAR BLACK-HOLES HARD STATE ACCRETION BINARY PULSATIONS POWER JETS EMISSION FLOWS |
| url | http://purl.org/au-research/grants/arc/FT140101082 http://hdl.handle.net/20.500.11937/80104 |