Understanding the X-ray spectrum of anomalous X-ray pulsars and soft gamma-ray repeaters

• Published in: Research in astronomy and astrophysics 2015-04, Vol.15 (4), p.525-536
• Main Authors: Guo, Yan-Jun, Dai, Shi, Li, Zhao-Sheng, Liu, Yuan, Tong, Hao, Xu, Ren-Xin
• Format: Article
• Language: English
• Subjects: Disks; Emission; Gamma rays; Modulation; Pulsars; Repeaters; Spectra; X-rays; X射线光谱; X射线发射; X射线辐射; 中继器; 伽马射线; 反常X射线脉冲星; 模型检测; 硬X射线调制望远镜
• ISSN: 1674-4527; 2397-6209
• DOI: 10.1088/1674-4527/15/4/006

Hard X-rays above 10 keV are detected from several anomalous X-ray pul- sars （AXPs） and soft gamma-ray repeaters （SGRs）, and different models have been proposed to explain the physical origin within the frame of either a magnetar model or a fallback disk system. Using data from Suzaku and INTEGRAL, we study the soft and hard X-ray spectra of four AXPs/SGRs： 1RXS J 170849-400910, 1E 1547.0- 5408, SGR 1806-20 and SGR 0501＋4516. It is found that the spectra could be well reproduced by the bulk-motion Comptonization （BMC） process as was first suggested by Triimper et al., showing that the accretion scenario could be compatible with X- ray emission from AXPs/SGRs. Simulated results from the Hard X-ray Modulation Telescope using the BMC model show that the spectra would have discrepancies from the power-law, especially the cutoff at -200 keV. Thus future observations will allow researchers to distinguish different models of the hard X-ray emission and will help us understand the nature of AXPs/SGRs.