Juri Poutanen (University of Oulu, Finland)

Modeling of X-ray burst spectral evolution: constraining the equation of state

In this talk I review the recent advances in spectral modeling of X-ray bursts. X-ray bursts are a powerful
tool to determine neutron star masses and radii, if the Eddington flux and the apparent radius in the cooling
tail can be measured accurately, and distances to the sources are known. I present a novel "cooling tail"
method of determining stellar parameters using the data from the whole cooling phase of the photospheric
radius expansion bursts. We apply this method to a number of X-ray bursters and constrain their radii and
masses. We also find that spectral evolution of the bursts strongly depends on the persistent flux. The
spectra of bursts at high accretion rates are strongly affected by the accretion flow and cannot therefore be
used for determination of the neutron star parameters.