Constraining the neutron star equation of state using XMM-Newton

Abstract

We have identified three possible ways in which future XMM-Newton observations can provide significant constraints on the equation of state of neutron stars. First, using a long observation of the neutron star X-ray transient CenX-4 in quiescence one can use the RGS spectrum to constrain the interstellar extinction to the source. This removes this parameter from the X-ray spectral fitting of the pn and MOS spectra and allows us to investigate whether the variability observed in the quiescent X-ray spectrum of this source is due to variations in the soft thermal spectral component or variations in the power law spectral component coupled with variations in N_H. This will test whether the soft thermal spectral component can indeed be due to the hot thermal glow of the neutron star. Potentially such an observation could also reveal redshifted spectral lines from the neutron star surface. Second, XMM-Newton observations of radius expansion type I X-ray bursts might reveal redshifted absorption lines from the surface of the neutron star. Third, XMM-Newton observations of eclipsing quiescent low-mass X-ray binaries provide the eclipse duration. With this the system inclination can be determined accurately. The inclination determined from the X-ray eclipse duration in quiescence, the rotational velocity of the companion star and the semi-amplitude of the radial velocity curve determined through optical spectroscopy, yield the neutron star mass.

arXiv comment4 pages, 1 figure, proceedings of the XMM-Newton workshop, June 2007, accepted for publication in AN

References in corpus (25)

• Neutron Star Cooling
• The Properties of X-Ray and Optical Light Curves of X-Ray Novae
• Gravitationally redshifted absorption lines in the X-ray burst spectra of a neutron star
• Crustal Heating and Quiescent Emission from Transiently Accreting Neutron Stars
• A Hydrogen Atmosphere Spectral Model Applied to the Neutron Star X7 in the Globular Cluster 47 Tucanae
• Exposing the Nuclear Burning Ashes of Radius Expansion Type I X-ray Bursts
• Variable Thermal Emission from Aql X-1 in Quiescence
• Variability in the Thermal Emission from Accreting Neutron Star Transients
• A Chandra observation of the long-duration X-ray transient KS 1731-260 in quiescence: too cold a neutron star?
• Charting the temperature of the Hot Neutron Star in a Soft X-ray Transient
• The Quiescent X-Ray Spectrum of the Neutron Star in Cen X-4 Observed with Chandra/ACIS-S
• X--Ray Spectra from Neutron Stars Accreting at Low Rates
• Constraints on Thermal X-ray Radiation from SAX J1808.4-3658 and Implications for Neutron Star Neutrino Emission
• X-ray Studies of Two Neutron Stars in 47 Tucanae: Toward Constraints on the Equation of State
• The variable quiescence of Cen X-4
• The Low Quiescent X-Ray Luminosity of the Neutron Star Transient XTE J2123-058
• Thermal emission from low-field neutron stars
• The cold neutron star in the soft X-ray transient 1H 1905+000
• The evolution of the high energy tail in the quiescent spectrum of the soft X-ray transient Aql X-1
• Chandra and RXTE Spectra of the Burster GS 1826-238
• The neutron star soft X-ray transient 1H1905+000 in quiescence
• Chandra observations of the neutron star soft X-ray transient RXJ170930.2-263927 returning to quiescence
• Rotational Broadening of Atomic Spectral Features from Neutron Stars
• Hiding in Plain Sight: Chandra Observations of the Quiescent Neutron Star 4U 2129+47 in Eclipse
• A Chandra observation of the globular cluster Terzan 1: the neutron-star X-ray transient X 1732-304 in quiescence

Cited by in corpus (1)

• Emission and Absorption Lines in Photospheric Radius Expansion Bursts of 4U 1820$-$30