Speaker
Description
Studies on ultraluminous X-ray sources (ULXs) became an
interesting topic in high-energy astrophysics in the 1980s when for the
first time they were observed during the X-ray surveys conducted by
Einstein Observatory and the ROSAT satellite. The X-ray emission from
these sources apparently exceeds the Eddington limit for neutron stars.
The discovery in 2014 of coherent pulsations in ULX emission revived
interest in the study of ULXs suggesting that the central object might
be a neutron star accreting beyond the Eddington limit.
Both numerical simulations and analysis of observational data are
necessary to explore the physics responsible for the pulsation and
high-rate X-ray emission of these objects.
We simulate accreting magnetized neutron stars and explore the effect of
the magnetic field on the accretion column structure and luminosity of
these objects. The simulations are performed in 2.5D with the resolution
of 512 x 510 using radiative general relativistic magnetohydrodynamics
code KORAL. We show that large magnetic fields truncate the disk and
quench the outflows which have an effect on lowering the luminosity. In
addition, our simulations show that the magnetic field strength affects
the beamed emission angle.