تقرير
Mixed H/He bursts in SAX J1748.9-2021 during the spectral change of its 2015 outburst
| العنوان: | Mixed H/He bursts in SAX J1748.9-2021 during the spectral change of its 2015 outburst |
|---|---|
| المؤلفون: | Li, Zhaosheng, De Falco, V., Falanga, M., Bozzo, E., Kuiper, L., Poutanen, J., Cumming, A., Galloway, D. K., Zhang, Shu |
| المصدر: | A&A 620, A114 (2018) |
| سنة النشر: | 2018 |
| المجموعة: | Astrophysics |
| مصطلحات موضوعية: | Astrophysics - High Energy Astrophysical Phenomena |
| الوصف: | SAX J1748.9-2021 is a transiently accreting X-ray millisecond pulsar. It is also known as an X-ray burster source discovered by Beppo-SAX. We analysed the persistent emission and type-I X-ray burst properties during its 2015 outburst. The source varied from hard to soft state within half day. We modeled the broad-band spectra of the persistent emission in the 1 - 250 keV energy band for both spectral states using the quasi-simultaneous INTEGRAL and Swift data. The broad-band spectra are well fitted by an absorbed thermal Componization model, compps, in a slab geometry. The best-fits for the two states indicate significantly different plasma temperature of 18 and 5 keV and the Thomson optical depth of 3 and 4, respectively. In total, 56 type-I X-ray bursts were observed during the 2015 outburst, of which 26 detected by INTEGRAL in the hard state, 25 by XMM-Newton in the soft state, and 5 by Swift in both states. As the object transited from the hard to the soft state, the recurrence time for X-ray bursts decreased from $\approx 2$ to $\approx1$ hr. The relation between the recurrence time, $ \Delta t_{\rm rec}$, and the local mass accretion rate per unit area onto the compact object, $\dot m$, is fitted by a power-law model, and yielded as best fit at $\Delta t_{\rm rec} \sim \langle \dot{m} \rangle^{-1.02\pm0.03}$ using all X-ray bursts. In both cases, the observed recurrence times are consistent with the mixed hydrogen/helium bursts. We also discuss the effects of type-I X-ray bursts prior to the hard to soft transition. Comment: Accepted for publication in A&A, 6 pages, 4 figures |
| نوع الوثيقة: | Working Paper |
| DOI: | 10.1051/0004-6361/201833857 |
| URL الوصول: | http://arxiv.org/abs/1810.05490 |
| رقم الأكسشن: | edsarx.1810.05490 |
| قاعدة البيانات: | arXiv |
| DOI: | 10.1051/0004-6361/201833857 |
|---|