Speaker
Dr
Tomohisa Kawashima
(National Astronomical Observatory of Japan)
Description
Ultra-luminous X-ray sources (ULXs) are extragalactic, off-nucleus, point-like X-ray sources with enormous luminosity $> 10^{39} ~[{\rm erg}~{\rm s}^{-1}]$, which exceeds the Eddington limit for stellar-mass black holes. Because of such a large luminosity, ULXs are expected to be powered by the super-Eddington accretion onto neutron stars or stellar-mass black holes, or sub-Eddington accretion onto intermediate-mass black holes. Recent discoveries of X-ray pulses in some ULXs have confirmed that the super-Eddington accretion onto neutron stars occurs in some ULXs. On the other hand, previous numerical studies showed that common X-ray spectral features of ULXs can be reproduced by the models of super-critically accreting steller-mass black holes. It is very important to reveal differences of the spectral features between super-critically accreting neutron stars and black holes, as well as their dynamics. Here, we present the results comparing dynamics and radiative spectra between super-Eddington accretion flows onto neutron stars and black holes, by performing general relativistic MHD simulations and by post-processing with general relativistic radiative transfer solver.
Primary author
Dr
Tomohisa Kawashima
(National Astronomical Observatory of Japan)
Co-authors
Dr
Hiroyuki R. Takahashi
(National Astronomical Observatory of Japan)
Prof.
Ken Ohsuga
(University of Tsukuba)
