solar neutron star, indicating a stiff equation of state at high densities. A comparison of the result with mass-radius diagrams shows that quark stars and neutron stars with quark matter cores can be ruled out with high confidence.">

The puzzles of RX J1856.5-3754: neutron star or quark star? (original) (raw)

NASA/ADS

;

Abstract

We discuss recent Chandra and XMM-Newton observations of the bright isolated neutron star RXJ1856.5-3754 and suggest that the absence of any line features is due to effects of a high magnetic field strength (~1013G). Using different models for the temperature distribution across the neutron star surface and assuming blackbody emission to fit the optical and X-ray spectrum, we derive a conservative lower limit of the "apparent`` neutron star radius of 16.5 km × (d/117 pc). This corresponds to the radius for the ''true`` (de-redshifted) radius of 14 km for a 1.4 Msolar neutron star, indicating a stiff equation of state at high densities. A comparison of the result with mass-radius diagrams shows that quark stars and neutron stars with quark matter cores can be ruled out with high confidence.

Publication:

Nuclear Physics B Proceedings Supplements

Pub Date:

June 2004

DOI:

10.1016/j.nuclphysbps.2004.04.094

arXiv:

arXiv:astro-ph/0312600

Bibcode:

2004NuPhS.132..560T

Keywords:

E-Print:

6 page, 2 figures, "The Restless High-Energy Universe" Proceedings of the symposium dedicated to six years of successful BeppoSAX operations Amsterdam, May 5-8, 2003