Constraints on the mass-radius relation of the neutron star in 4U 1746-37/NGC 6441.
Abstract
An analysis of 12 hours of continuous EXOSAT observations of 4U 1746-37 in NGC 6441, obtained between September 9 and 10, 1985, puts constraints on its mass-radius relation. The spectral shape of the persistent X-ray flux is well fitted by a thermal bremsstrahlung spectrum, with a kT temperature varying between 7.5 and 9.8 keV, and an interstellar column density of about 2.8 x 10 to the 21st/sq cm. Two X-ray bursts noted during the observation are found to be type I, with radius expansion of the neutron star photosphere during their peaks. If the neutron star has a canonical mass of 1.4 solar masses, the observed burst fluxes must be reduced as a result of anisotropy of the burst by a factor of at least 1.3-2.2. The present results are consistent with the very soft and intermediately stiff equations of state.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- May 1987
- DOI:
- 10.1093/mnras/226.1.39
- Bibcode:
- 1987MNRAS.226...39S
- Keywords:
-
- Neutron Stars;
- Size Determination;
- Stellar Magnitude;
- Stellar Mass;
- Bremsstrahlung;
- Photosphere;
- Stellar Atmospheres;
- X Ray Spectra;
- Astrophysics