Implications of high-precision spectra of thermonuclear X-ray bursts for determining neutron star masses and radii

TL;DR

This study reveals that traditional neutron star spectral models are inconsistent with high-precision X-ray burst data, suggesting a need to revise methods for accurately determining neutron star masses and radii.

Contribution

The paper demonstrates that previous model atmospheres do not match high-precision spectra, proposing simpler Bose-Einstein spectra as a better fit, impacting neutron star parameter estimates.

Findings

Published model atmospheres are inconsistent with high-precision spectra.

A Bose-Einstein spectrum fits the data well.

Implications for neutron star mass and radius measurements.

Abstract

X-ray burst spectra have long been used to estimate neutron star masses and radii. These estimates assumed that burst spectra are accurately described by the model atmosphere spectra developed over the last three decades. We compared RXTE data from a superburst with these spectra and found that the spectra predicted by previously published model atmospheres are strongly inconsistent with these high-precision measurements. In contrast, a simple Bose-Einstein spectrum is fully consistent with the data, as are recently published model atmosphere spectra. We discuss the implications of our results for determinations of neutron star masses and radii via constraints on their surface gravity and redshift, as originally suggested by Majczyna and Madej.