Program
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Constraining Neutron Star Masses and Radii Using High Resolution Spectra
Feryal Ozel
University of Arizona
Abstract:
While recent X-ray missions provide us with high resolution spectra of
thermally emitting neutron stars, the largest uncertainties in determining
neutron star masses and radii from from these spectra are still
theoretical. In order to obtain accurate constraints, (i) the surface
layers of neutron stars need to be modeled in detail, (ii) the effects of
strong gravity and rotation on surface emission need to be taken into
account, and (iii) possible temperature non-uniformity and unknown
emission geometry need to be addresses. In this talk, I will discuss
recent models of neutron star surface layers and the general relativistic
effects on the surface, pointing out the uncertainties in mass-radius
determination arising from each. I will then show how combining timing
information of neutron stars with their spectra reduces greatly the
uncertainties arising from general relativistic and geometrical effects.
Finally, I will discuss how combining several different spectral and
timing measurements of X-ray sources provides us with complementary and
the most promising method for accurate determination of neutron star
masses and radii, as well as minimizes observational uncertainties such as
source distances.
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