Comprehensive modelling of pulse shape formation in binary X-ray pulsars

X射线双星的高能辐射来源于电离气体在强磁化旋转中子星上的吸积。如果磁轴和旋转轴不对齐，则观察到脉冲发射。吸积X射线源显示出各种各样的脉冲形状，这是每个源的特征。近年来，由于几颗卫星的出色观测，获得了越来越丰富的关于光谱和脉冲形状的高质量观测数据。然而，经过近四十年的研究，仍然没有令人信服的模型可以应用于从X射线脉冲星的脉冲形状推断其几何和物理参数。在这个项目中，我们的目标是更好地了解脉冲形状形成的机制。我们将开发和研究一套全面的现象学模型，并将其与宽带观测数据进行比较。这些模型将充分考虑相对论性光偏转，并将包括一些重要的影响，到目前为止已经包括在几个模型（然后单独）或已被讨论，只有在定性的方式：晕形成，吸积流日食，再处理晕辐射，和不同的吸积流几何形状。最终，我们期望不仅达到吸积脉冲星发射的相关机制的深刻理解，但也设置这样的系统的关键物理参数，如质量，半径，磁矩和磁场配置的中子星星，吸积率，磁和旋转轴之间的偏移，吸积丘几何约束。

High energy radiation from X-ray binary pulsars originates from the accretion of ionized gas onto strongly magnetized rotating neutron stars. If the magnetic and rotation axes are disaligned, pulsed emission is observed. Accreting X-ray pulsars display a large variety of pulse shapes, that are characteristic for each source. In recent years an increasing wealth of high quality observational data on spectra and pulse shapes has been obtained thanks to the outstanding observations of several satellites. However, after almost four decades of research, there is still no compelling model that one could apply to infer the geometric and physical parameters of X-ray pulsars from their pulse shapes. In this project we aim at a better understanding of the mechanisms of pulse shape formation. We will develop and study a set of comprehensive phenomenological models and compare them to broadband observational data. These models will take full account of relativistic light deflection and will include a number of important effects that have so far been included in few models (and then separately) or have been discussed only in a qualitative way: halo formation, accretion stream eclipses, reprocessing of halo radiation, and different accretion stream geometries. Eventually we expect not only to reach a deep understanding of the mechanisms relevant to accreting pulsar emission but also to set constraints on key physical parameters of such systems like mass, radius, magnetic moment and magnetic field configuration of the neutron star, accretion rate, offset between magnetic and rotation axes, accretion mound geometry.