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The evolving jet spectrum of the neutron star X-ray binary Aql X-1 in transitional states during its 2016 outburst

The evolving jet spectrum of the neutron star X-ray binary Aql X-1 in transitional states during its 2016 outburst
The evolving jet spectrum of the neutron star X-ray binary Aql X-1 in transitional states during its 2016 outburst

We report on quasi-simultaneous observations from radio to X-ray frequencies of the neutron star X-ray binary Aql X-1 over accretion state transitions during its 2016 outburst. All the observations show radio to millimetre spectra consistent with emission from a jet, with a spectral break from optically thick to optically thin synchrotron emission that decreases from ∼100 GHz to <5.5 GHz during the transition from a hard to a soft accretion state. The 5.5 GHz radio flux density as the source reaches the soft state, 0.82 ± 0.03 mJy, is the highest recorded to date for this source. During the decay of the outburst, the jet spectral break is detected again at a frequency of ∼30-100 GHz. The flux density is 0.75 ± 0.03 mJy at 97.5 GHz at this stage. This is the first time that a change in the frequency of the jet break of a neutron star X-ray binary has been measured, indicating that the processes at play in black holes are also present in neutron stars, supporting the idea that the internal properties of the jet rely most critically on the conditions of the accretion disc and corona around the compact object, rather than the black hole mass or spin or the neutron star surface or magnetic field.

Accretion, accretion disks, ISM: Jets and outflows, Stars: neutron, X-rays: Binaries, X-rays: Individuals: Aql X-1
0004-6361
Díaz Trigo, M.
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Altamirano, D.
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Dinçer, T.
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Miller-Jones, J. C.A.
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Russell, D.M.
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Sanna, A.
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Bailyn, C.
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Lewis, F.
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Migliari, S.
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Rahoui, F.
d98ca9b7-6a98-40ad-8a0f-f278d044ffec
Díaz Trigo, M.
04422ade-9ae6-434c-98bc-50d0ac75e19e
Altamirano, D.
d5ccdb09-0b71-4303-9538-05b467be075b
Dinçer, T.
2a828a95-d8ff-4721-b0e7-85899e64e998
Miller-Jones, J. C.A.
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Russell, D.M.
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Sanna, A.
b925b305-171b-461f-bbf7-1c8fe246293c
Bailyn, C.
59295344-e9fb-47c5-b741-13a55c4788bd
Lewis, F.
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Migliari, S.
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Rahoui, F.
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Díaz Trigo, M., Altamirano, D., Dinçer, T., Miller-Jones, J. C.A., Russell, D.M., Sanna, A., Bailyn, C., Lewis, F., Migliari, S. and Rahoui, F. (2018) The evolving jet spectrum of the neutron star X-ray binary Aql X-1 in transitional states during its 2016 outburst. Astronomy and Astrophysics, 616, [A23]. (doi:10.1051/0004-6361/201832693).

Record type: Article

Abstract

We report on quasi-simultaneous observations from radio to X-ray frequencies of the neutron star X-ray binary Aql X-1 over accretion state transitions during its 2016 outburst. All the observations show radio to millimetre spectra consistent with emission from a jet, with a spectral break from optically thick to optically thin synchrotron emission that decreases from ∼100 GHz to <5.5 GHz during the transition from a hard to a soft accretion state. The 5.5 GHz radio flux density as the source reaches the soft state, 0.82 ± 0.03 mJy, is the highest recorded to date for this source. During the decay of the outburst, the jet spectral break is detected again at a frequency of ∼30-100 GHz. The flux density is 0.75 ± 0.03 mJy at 97.5 GHz at this stage. This is the first time that a change in the frequency of the jet break of a neutron star X-ray binary has been measured, indicating that the processes at play in black holes are also present in neutron stars, supporting the idea that the internal properties of the jet rely most critically on the conditions of the accretion disc and corona around the compact object, rather than the black hole mass or spin or the neutron star surface or magnetic field.

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1804.08322v1 - Accepted Manuscript
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Accepted/In Press date: 20 April 2018
e-pub ahead of print date: 7 August 2018
Published date: August 2018
Additional Information: Reproduced with permission from Astronomy & Astrophysics, © ESO
Keywords: Accretion, accretion disks, ISM: Jets and outflows, Stars: neutron, X-rays: Binaries, X-rays: Individuals: Aql X-1

Identifiers

Local EPrints ID: 424427
URI: http://eprints.soton.ac.uk/id/eprint/424427
ISSN: 0004-6361
PURE UUID: 5ce36083-2763-45f7-a4b8-c2d6afb760ff
ORCID for D. Altamirano: ORCID iD orcid.org/0000-0002-3422-0074

Catalogue record

Date deposited: 05 Oct 2018 11:37
Last modified: 26 Nov 2021 03:02

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Contributors

Author: M. Díaz Trigo
Author: D. Altamirano ORCID iD
Author: T. Dinçer
Author: J. C.A. Miller-Jones
Author: D.M. Russell
Author: A. Sanna
Author: C. Bailyn
Author: F. Lewis
Author: S. Migliari
Author: F. Rahoui

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