Studying temporal variability of GRS1739-278 during the 2014 outburst
Abstract
We report a discovery of low-frequency quasi-periodic oscillation at 0.3–0.7 Hz in the power spectra of the accreting black hole GRS 1739–278 in the hard-intermediate state during its 2014 outburst based on the NuSTAR and Swift/XRT data. The QPO frequency strongly evolved with the source flux during the NuSTAR observation. The source spectrum became softer with rising QPO frequency and simultaneous increasing of the power-law index and decreasing of the cut-off energy. In the power spectrum, a prominent harmonic is clearly seen together with the main QPO peak. The fluxes in the soft and the hard X-ray bands are coherent, however, the coherence drops for the energy bands separated by larger gaps. The phase lags are generally positive (hard) in the 0.1–3 Hz frequency range, and negative below 0.1 Hz. The accretion disc inner radius estimated with the relativistic reflection spectral model appears to be R_(in) < 7.3R_g. In the framework of the relativistic precession model, in order to satisfy the constraints from the observed QPO frequency and the accretion disc truncation radius, a massive black hole with M_(BH) ≈ 100 M⊙ is required.
Additional Information
© 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model). Accepted 2018 October 9. Received 2018 September 4; in original form 2018 June 27. Published: 12 October 2018. This work was supported by the Russian Science Foundation grant no. 14-12-01287. We thank E. M. Churazov for fruitful discussions and useful suggestions. We are grateful for T. Dauser and J. Gracia for their help with RELXILL model. This research has made use of data obtained through the High Energy Astrophysics Science Archive Research Center Online Service, provided by the NASA/Goddard Space Flight Center, as well as of data supplied by the UK Swift Science Data Centre at the University of Leicester.Attached Files
Accepted Version - 1810.04451.pdf
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Additional details
- Eprint ID
- 90242
- Resolver ID
- CaltechAUTHORS:20181011-090326652
- 14-12-01287
- Russian Science Foundation
- Created
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2018-10-11Created from EPrint's datestamp field
- Updated
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2021-11-16Created from EPrint's last_modified field
- Caltech groups
- NuSTAR