AstroSat and NuSTAR observations of XTE J1739-285 during the 2019-2020 outburst
AstroSat and NuSTAR observations of XTE J1739-285 during the 2019-2020 outburst
We report results from a study of XTE J1739-285, a transient neutron star low mass X-ray binary observed with AstroSat and NuSTAR during its 2019-2020 outburst. We detected accretion-powered X-ray pulsations at 386 Hz during very short intervals (0.5-1 s) of X-ray flares. These flares were observed during the 2019 observation of XTE J1739-285. During this observation, we also observed a correlation between intensity and hardness ratios, suggesting an increase in hardness with the increase in intensity. Moreover, a thermonuclear X-ray burst detected in our AstroSat observation during the 2020 outburst revealed the presence of coherent burst oscillations at 383 Hz during its decay phase. The frequency drift of 3 Hz during X-ray burst can be explained with r modes. Thus, making XTE J1739-285 belong to a subset of NS-LMXBs which exhibit both nuclear- and accretion-powered pulsations. The power density spectrum created using the AstroSat-laxpc observations in 2020 showed the presence of a quasi-periodic oscillation at ∼0.83 Hz. Our X-ray spectroscopy revealed significant changes in the spectra during the 2019 and 2020 outburst. We found a broad iron line emission feature in the X-ray spectrum during the 2020 observation, while this feature was relatively narrow and has a lower equivalent width in 2019, when the source was accreting at higher rates than 2020. Hard X-ray tail was observed during the 2019 observations, indicating the presence of non-thermal component in the X-ray spectra.
X-ray: binaries, X-rays: bursts, X-rays: individual (XTE J1739-285), accretion, accretion discs, stars: neutron, accretion, accretion discs
5904-5916
Beri, Aru
69ed346a-f02a-4243-83f9-ad5ab4c4008c
Sharma, Rahul
76683c23-736b-450c-9c4e-2d18726c4b63
Roy, Pinaki
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Gaur, Vishal
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Altamirano, Diego
d5ccdb09-0b71-4303-9538-05b467be075b
Andersson, Nils
2dd6d1ee-cefd-478a-b1ac-e6feedafe304
Gittins, Fabian
657ec875-fac3-4606-9dcd-591ef22fc9f6
Celora, T.
b15e9792-aae0-479a-83c5-b5c874b19fa6
1 June 2023
Beri, Aru
69ed346a-f02a-4243-83f9-ad5ab4c4008c
Sharma, Rahul
76683c23-736b-450c-9c4e-2d18726c4b63
Roy, Pinaki
6dfc8561-2830-42d2-bde1-191db0cc29b0
Gaur, Vishal
1d2cda70-6210-400d-a862-b78bbf4604f1
Altamirano, Diego
d5ccdb09-0b71-4303-9538-05b467be075b
Andersson, Nils
2dd6d1ee-cefd-478a-b1ac-e6feedafe304
Gittins, Fabian
657ec875-fac3-4606-9dcd-591ef22fc9f6
Celora, T.
b15e9792-aae0-479a-83c5-b5c874b19fa6
Beri, Aru, Sharma, Rahul, Roy, Pinaki, Gaur, Vishal, Altamirano, Diego, Andersson, Nils, Gittins, Fabian and Celora, T.
(2023)
AstroSat and NuSTAR observations of XTE J1739-285 during the 2019-2020 outburst.
Monthly Notices Of The Royal Astronomical Society, 521 (4), .
(doi:10.1093/mnras/stad902).
Abstract
We report results from a study of XTE J1739-285, a transient neutron star low mass X-ray binary observed with AstroSat and NuSTAR during its 2019-2020 outburst. We detected accretion-powered X-ray pulsations at 386 Hz during very short intervals (0.5-1 s) of X-ray flares. These flares were observed during the 2019 observation of XTE J1739-285. During this observation, we also observed a correlation between intensity and hardness ratios, suggesting an increase in hardness with the increase in intensity. Moreover, a thermonuclear X-ray burst detected in our AstroSat observation during the 2020 outburst revealed the presence of coherent burst oscillations at 383 Hz during its decay phase. The frequency drift of 3 Hz during X-ray burst can be explained with r modes. Thus, making XTE J1739-285 belong to a subset of NS-LMXBs which exhibit both nuclear- and accretion-powered pulsations. The power density spectrum created using the AstroSat-laxpc observations in 2020 showed the presence of a quasi-periodic oscillation at ∼0.83 Hz. Our X-ray spectroscopy revealed significant changes in the spectra during the 2019 and 2020 outburst. We found a broad iron line emission feature in the X-ray spectrum during the 2020 observation, while this feature was relatively narrow and has a lower equivalent width in 2019, when the source was accreting at higher rates than 2020. Hard X-ray tail was observed during the 2019 observations, indicating the presence of non-thermal component in the X-ray spectra.
Text
2303.13085v1
- Accepted Manuscript
More information
Accepted/In Press date: 21 March 2023
Published date: 1 June 2023
Additional Information:
Publisher Copyright:© 2023 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.
Keywords:
X-ray: binaries, X-rays: bursts, X-rays: individual (XTE J1739-285), accretion, accretion discs, stars: neutron, accretion, accretion discs
Identifiers
Local EPrints ID: 477882
URI: http://eprints.soton.ac.uk/id/eprint/477882
ISSN: 1365-2966
PURE UUID: 083d829e-0437-4f69-9efa-1771edc29bbf
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Date deposited: 15 Jun 2023 17:02
Last modified: 18 Mar 2024 02:49
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Contributors
Author:
Aru Beri
Author:
Rahul Sharma
Author:
Pinaki Roy
Author:
Vishal Gaur
Author:
Fabian Gittins
Author:
T. Celora
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