Evidence for Atomic Absorption Features in the High Resolution X-ray Spectrum of the Neutron Star in Puppis A

TL;DR

This study detects atomic absorption lines in the X-ray spectrum of a neutron star, providing spectroscopic estimates of its radius and mass, and confirming magnetic field strength through Zeeman effects.

Contribution

It presents the first spectroscopic measurements of neutron star radius and mass, and confirms magnetic field strength via Zeeman effect in high-resolution X-ray spectra.

Findings

Detection of atomic absorption lines in X-ray spectrum.

Spectroscopic confirmation of magnetic field strength.

First purely spectroscopic estimates of neutron star radius and mass.

Abstract

We present evidence for atomic absorption lines in the high-resolution 4-30 A X-ray spectrum of the neutron star RX J0822-4300 in the supernova remnant Puppis A. Comparison with model atmosphere calculations shows that features in the observed spectrum can be uniquely associated with redshifted and pressure-broadened transitions in highly ionized oxygen and neon. We also spectroscopically confirm the previously estimated strength of the surface magnetic dipole field; we detect both the linear and the quadratic Zeeman effect. We derive values for both the gravitational redshift and the acceleration of gravity at the stellar surface, yielding the first purely spectroscopic estimates for the radius and mass of a neutron star.