| Autor: |
Bharali, Priya, Chandra, Sunil, Chauhan, Jaiverdhan, García, Javier A, Roy, Jayashree, Boettcher, Markus, Boruah, Kalyanee |
| Předmět: |
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| Zdroj: |
Monthly Notices of the Royal Astronomical Society; 8/15/2019, Vol. 487 Issue 3, p3150-3161, 12p |
| Abstrakt: |
In this work, we present a spectral and temporal analysis of Swift /XRT and NuSTAR observations of GRS 1716–249 during its recent 2016–2017 outburst. This low-mass X-ray binary underwent an extraordinary outburst after a long quiescence of 23 yr, since its last major outburst in 1993. The source was observed over two different epochs during 2017 April 7 and 10. The best-fitting joint spectral fitting in the energy range 0.5–79.0 keV indicates that the spectrum is best described by relatively cold, weak disc blackbody emission, dominant thermal Comptonization emission, and a relativistically broadened fluorescent iron K α emission line. We observed a clear indication of a Compton hump around 30 keV. We also detected an excess feature of 1.3 keV. Assuming a lamp-post geometry of the corona, we constrained the inner disc radius for both observations to 11.92 |$^{+8.62}_{-11.92}$| R ISCO (i.e. an upper limit) and 10.39 |$^{+9.51}_{-3.02}$| R ISCO (where R ISCO ≡ radius of the innermost stable circular orbit) for the first epoch (E1) and second epoch (E2), respectively. A significant (5σ) type C quasi-periodic oscillation (QPO) at 1.20 ± 0.04 Hz is detected for the first time for GRS 1716–249, which drifts to 1.55 ± 0.04 Hz (6σ) at the end of the second observation. The derived spectral and temporal properties show a positive correlation between the QPO frequency and the photon index. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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