ROSAT HRI Observations of the Crab Pulsar: An Improved Temperature upper limit for PSR 0531+21

TL;DR

This study uses ROSAT HRI data to set a new, lower upper limit on the surface temperature of the Crab pulsar, refining previous constraints and considering different neutron star models.

Contribution

It provides the most stringent temperature upper limit for the Crab pulsar to date, based on X-ray observations and neutron star modeling.

Findings

Surface temperature upper limit: $T_s^ \, .55 imes 10^6$ K

Lower temperature limit than previous measurements

Temperature varies with neutron star equation of state

Abstract

ROSAT HRI observations have been used to determine an upper limit of the Crab pulsar surface temperature from the off-pulse count rate. For a neutron star mass of 1.4 \Mo and a radius of 10 km as well as the standard distance and interstellar column density, the redshifted temperature upper limit is\/ $T_s^\infty \le 1.55\times 10^6$ K $(3\sigma)$. This is the lowest temperature upper limit obtained for the Crab pulsar so far. Slightly different values for $T_s^\infty$ are computed for the various neutron star models available in the literature, reflecting the difference in the equation of state.