Astrophysics

Theory of accreting X-ray pulsars

Accreting X-ray pulsars are among the brightest X-ray sources in the Milky Way. They are binary systems with mass transfer from a normal star onto a neutron star. The light curve of their periodically varying X-ray flux is characteristic for each source. While the origin of the X-radiation is well understood, a comprehensive understanding of the pulse shapes is still lacking.

For an Introduction to X-ray pulsars and to our research work (with movies) see the contribution X-ray pulsars (in German) on our website space time travel.

Current projects:

1. Analysis of observed pulse shapes

We analyze observed pulse shapes using the decomposition method developed by our group. The analysis aims at determining properties of the accreting neutron stars (magnetic field configuration, orientation of the magnetic field with respect to the axis of rotation) and of the X-ray emission regions (spectrum and directionality of the emission pattern). The data obtained in the analysis serve as input for model calculations that aim at a detailed interpretation of the pulse shapes.

2. Modelling pulse shape formation

We develop multi-component models that include reprocessing of radiation and all relativistic effects in the Schwarzschild spacetime of a neutron star. The goals are to identify the mechanisms that are most relevant in the formation of the pulse shapes and to find detailed interpretations of observed pulse shapes.