RX J1856-3754: Evidence for a stiff EOS
Aug, 20026 pages
Published in:
- Astrophys.J. 580 (2002) 1043-1047
e-Print:
- astro-ph/0208069 [astro-ph]
DOI:
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Abstract: (arXiv)
We have examined the soft X-ray plus optical/UV spectrum of the nearby isolated neutron star RX J1856-3754, comparing with detailed models of a thermally emitting surface. Like previous investigators, we find the spectrum is best fit by a two-temperature blackbody model. In addition, our simulations constrain the allowed viewing geometry from the observed pulse fraction upper limits. These simulations show that RX J1856-3754 is very likely to be a normal young pulsar, with the non-thermal radio beam missing Earth's line of sight. The SED limits on the model parameter space put a strong constraint on the star's M/R. At the measured parallax distance, the allowed range for Mstar=1.5Msun is Rstar=13.7+/-0.6km. Under this interpretation, the EOS is relatively stiff near nuclear density and the `Quark Star' EOS posited in some previous studies is strongly excluded. The data also constrain the surface T distribution over the polar cap.References(23)
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