Disc reflection in low-mass X-ray binaries

X-ray binaries are systems consisting of a compact object, either a black hole or a neutron star, and a companion star, both orbiting a common centre of mass of the system. When the companion star in an X-ray system is a late-type main sequence star or a white dwarf with mass typically lower than a solar mass, this system is called a low-mass X-ray binary (LMXB). In such a system, the matter from the companion is accreted onto the compact object and forms a rotating disc. During this accretion process, X-rays are generated when the gravitational energy of the in-falling matter is converted into radiation due to viscous processes. However, the observed energy of the X-rays is much higher than the disc emission, which indicates the existence of another region emitting hard X-rays. This region is called corona.

The interaction between the corona and the accretion disc produces disc reflection, which is a powerful tool to diagnose the physical and dynamical conditions of accretion flow. This thesis mainly focuses on the study of the X-ray properties of the accretion flow in several LMXBs with disc reflection. Timing and spectral analysis have been employed for this purpose. The results show that modelling reflection features has led to important constraints on not only the physical parameters of the disc but also the spin parameter of the compact object.

Dissertation: http://hdl.handle.net/11370/9cee5ffd-b4ac-4ace-a4f1-76039396efa2