Mass and radius determination for the neutron star in X-ray burst source 4U/MXB 1728-34
Abstract
We analyzed archival X-ray spectra of MXB 1728-34 obtained in 1996-99 by the Proportional Counter Array on board of the RXTE satellite. X-ray spectra were fitted to our extensive grids of model atmosphere spectra to determine the effective temperature Teff on the neutron star surface, logarithm of surface gravity log(g), and the gravitational redshift z simultaneously. We have chosen fitting by numerical model spectra plus broad Gaussian line, modified by interstellar absorption and the absorption on dust. We arbitrarily assumed either hydrogen-helium chemical composition of a model atmosphere, or H-He-Fe mixture in solar proportion. The statistically best values of log(g), and z subsequently were used to determine mass and radius of the neutron star. We obtained the best values of the parameters for the neutron star in X-ray burst source MXB 1728-34: mass either M=0.40 or 0.63 Msol (for H-He or H-He-Fe models, respectively), radius R=4.6 or 5.3 km, log(g)=14.6 or 14.6 and the gravitational redshift z=0.14 or 0.22. All the above parameters have very wide 1-sigma confidence limits. Their values strongly support the equation of state for strange matter in MXB 1728-34.
Turn this paper into a full lesson
ArcXiv compiles a staged curriculum from this paper: 8-12 lessons across beginner → advanced, synthesised section guides, visuals, flashcards, a quiz, exercises, and on-demand deep dives per section. Grounded in the abstract, never invented.