A broad spectral feature detected during the cooling phase of a type I X-ray burst from GRS 1747-312 with Suzaku

作者：Iwai Masachika^*; Dotani Tadayasu; Ozaki Masanobu; Maeda Yoshitomo; Mori Hideyuki; Saji Shigetaka

来源：Publications of the Astronomical Society of Japan, 2017, 69(4): 61.

DOI：10.1093/pasj/psx037

• nuclear reactions, nucleosynthesis, abundances
• stars: neutron
• X-rays: binaries
• X-rays: bursts
• X-rays: individual (GRS 1747-312)

We analyzed the Suzaku archive data of a type I X-ray burst from GRS1747-312, a low mass X-ray binary located in the globular cluster Terzan 6. During the Galactic bulge mapping observations with Suzaku, which covered Terzan 6, an X-ray burst of long duration and with moderate photospheric-radius expansion was serendipitously detected and was considered to be most probably originating from GRS1747-312. The time-divided burst spectra were reproduced well with an absorbed blackbody over the majority of the time, but significant deviation was detected late in the cooling phase. The deviation was due to a rolled-off feature, which gradually developed in the cooling phase of the burst, in the energy spectra above similar to 7 keV. We tested various models to reproduce the spectral feature and found three types of models (reflection by cold matter, partial-covering absorption, and Doppler-smeared absorption edges due to the rapid spin of a neutron star) gave a statistically acceptable fit. We discussed the feasibility of these models, including a non-Planckian nature of the burst spectra.

• 出版日期2017-8