HXMT研究脉冲星的硬X射线/软γ射线辐射

We carry out theoretical and observational studies of the hard X-ray/soft gamma-ray emissions from the pulsar with using the Hard X-ray Telescope Monitor (HXMT). At the hard X-ray/soft gamma-ray bands, theoretical studies expecte that the pulsar emission process rom the curvature radiation process (or inverse-Compton scattering process) in GeV bands to the synchrotron process in the soft X-ray bands. It can be said hat a detail observation of HXMT is crucial to understand the multi-wavelength nature of the high-energy pulsars. In comparison to GeV pulsars (200 sources), however, number of pulsars seen at hard X-ray/soft gamma-ray (>10keV) remains small (~15 sources). Moreover, current data in the X-ray/soft gamma-rays include relatively large uncertainties. The current observations cannot provide enough information of the hard X-ray/soft gamma-ray emission of the pulsars. . With the wide coverage in the energy bands, HXMT perfectly suits for studying the hard X-ray/soft gamma-ray emission of the pulsar, and provide new insight the physical processes occurred in the pulsar magnetosphere. In the proposed project, we carry out a deep study of the hard X-ray/soft gamma-ray emissions from the Crab pulsar and PSR B1509-58, for which HXMT regularly collects the data. Although PSR B1509-58 is a young and energetic pulsar, it shows a dim GeV gamma-ray emission. It also shows a bright hard X-ray emission in comparison to other GeV pulsars. To understand what causes this difference in the spectra, it is important to fill the observational gap between the soft X-ray and the GeV gamma-ray bands. HXMT will enable us to carry out a detail study for the pulse profile and phase-resolved spectrum. The results will be compared with a three-dimensional radiation model. . In the theoretical study, we explore the possibilities that the difference in the spectral properties between the GeV gamma-ray pulsar and PSR B1509-58 is mainly caused by the difference in the viewing geometry. We will simulate the dependency of X-ray/gamma-ray spectra and light curves on the viewing geometry, and we will discuss if this model could explain the observations of HXMT.. About 5 young energetic pulsars show similar spectral behavior to PSR B1509-58, and they probably emit an observable hard X-ray emission with HXMT. In the project, therefore, we propose the observation of these pulsars (so called soft gamma-ray pulsars) with HXMT and we reveal the nature of the non-thermal emissions of the soft gamma-ray pulsars. PSR B1509-58 and other soft gamma-ray pulsars will be a primary target for future MeV telescopes, because they will be one of the brightest MeV sources in the sky. Our study in the proposed project can be a preceding research for the future MeV observations

我们对脉冲星的硬X射线/软伽马射线发射进行理论和观测研究。 与GeV伽马射线脉冲星（200个源）相比，在硬X射线/软伽马射线（> 10keV）处看到的脉冲星数量仍然很少（约15个源）。 随着能带范围的广泛覆盖，HXMT非常适合研究脉冲星的硬X射线/软伽马射线发射，并为脉冲星磁层发生的物理过程提供新的见解。 在提议的项目中，为了HXMT定期收集这些数据我们深入研究了Crab脉冲星和PSR B1509-58的硬X射线/软伽马射线辐射。 我们将模拟X射线/伽玛射线光谱和光线曲线对观察几何形状的依赖关系，并且会讨论这个模型是否可以解释HXMT的观察结果。 我们在拟议项目中的研究可能是未来MeV观测的前期研究

我们对具有高能辐射的孤立脉冲星以及白矮星双星系统AR Scorpii展开了详细的理论和观测研究。MeV脉冲星是指能谱峰值频率在MeV波段的年轻脉冲星，其在GeV波段的辐射往往很弱或者甚至没有辐射。MeV脉冲星在X射线和软伽马射线波段的辐射特征与Fermi-LAT探测到的GeV脉冲星有着明显的区别。在本项目中，我们对5个MeV脉冲星在X射线波段的辐射特性展开了详细的研究，并对这类脉冲星的起源进行了探讨。.PSR J2021+4026是第一个被发现的辐射流量呈现明显变化的伽马射线脉冲星。这颗脉冲星在2011年10月发生了一次周期跃变。在本项目中，我们通过Fermi-LAT对PSR J2021+4026长达11年的观测数据的分析，仔细研究了这颗脉冲星在GeV波段流量的长时标演化。我们发现PSR J2021+4026每隔7年左右发生一次周期跃变，每次跃变都会导致其伽马射线辐射特征发生显著变化。.PSR J1119−6127在2016年7月27日至28日期间发生了一次类似于磁星的X射线爆发。在这次爆发之后，这颗脉冲星伴随着非常显著的周期跃变现象。我们对其展开了详细的多波段辐射研究，并探讨了脉冲星在发生周期跃变过程中磁层结构的变化。我们提出PSR J1119−6127在发生爆发之后，其X射线辐射的演化行为可以用脉冲星磁层中磁力线的解扭过程来解释，且该过程的持续时标为半年左右。.AR Scorpii是一个由快速旋转的白矮星和M型恒星组成，并且有着从射电到X射线波段的非热辐射的双星系统，其中白矮星的自转周期约为117秒。AR Scorpii的光学辐射随白矮星的自转频率呈现规律的变化，并且具有较高的线偏振度（约为40%）。观测还发现偏振的位置角在白矮星的自转周期内呈现360度的变化。我们提出白矮星的磁场与M型伴星的相互作用产生相对论电子并且被束缚在白矮星的磁层里，这些电子通过同步辐射产生从射电到X射线的非热辐射。该模型可以很好地解释AR Scorpii的偏振特性。除此之外，我们还分析了XMM-Newton、Chandra、NICER和NuSTAR于2016年至2020年期间对AR Scorpii的X射线观测数据。