AstroSat observation of rapid type-I thermonuclear burst from low-mass X-ray binary GX 3+1
Abstract
We report the results of an observation of low-mass X-ray binary GX 3+1 with AstroSat's large area X-ray proportional counter (LAXPC) and soft X-ray telescope (SXT) instruments on-board for the first time. We have detected type-I thermonuclear burst (∼15 s) present in the LAXPC 20 light curve with a double peak feature at higher energies and our study of the hardness-intensity diagram reveals that the source was in a soft banana state. The pre-burst emission could be described well by a thermally Comptonized model component. The burst spectra is modeled adopting a time-resolved spectroscopic method using a single color blackbody model added to the pre-burst model, to monitor the parametric changes as the burst decays. Based on our time-resolved spectroscopy, we claim that the detected burst is a photospheric radius expansion (PRE) burst. During the PRE phase, the blackbody flux is found to be approximately constant at an averaged value of ∼2.56 in 10-8 ergs s-1 cm-2 units. On the basis of literature survey, we infer that AstroSat/LAXPC 20 has detected a burst from GX 3+1 after more than a decade, which is also a PRE one. Utilizing the obtained burst parameters, we provide a new estimation to the source distance, which is ∼9.3 ±0.4 kpc, calculated for an isotropic burst emission. Finally, we discuss and compare our findings with the published literature reports.
- Publication:
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Journal of Astrophysics and Astronomy
- Pub Date:
- December 2022
- DOI:
- 10.1007/s12036-022-09878-9
- arXiv:
- arXiv:2206.07450
- Bibcode:
- 2022JApA...43...93N
- Keywords:
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- X-rays: binaries—stars: neutron—pulsars: individual: GX 3+1—X-rays: stars—methods: data analysis—AstroSat:;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 14 pages, 10 figures, accepted for publication in The Journal of Astrophysics and Astronomy