Thermal Spectrum and Neutrino Cooling Rate of the Vela Pulsar

Dmitry Ofengeim,Dmitry Zyuzin

doi:10.3390/particles1010014

Abstract

We reanalyse the X-ray spectrum of the PSR B0833–45 (the Vela pulsar) using the data of the Chandra space observatory. In contrast to previous works, we consider a wide range of possible masses and radii of the pulsar. The derived surface temperature of the star Ts∞=0.66−0.01+0.04MK (1σ level over the entire mass and radius range of our study) is consistent with earlier results. However, the preferable values of Vela’s mass and radius given by the spectral analysis are different from those used previously; they are consistent with modern equation of state models of neutron star matter. In addition, we evaluate the Vela’s surface temperature as a function of assumed values of its mass and radius. This allows us to analyse the neutrino cooling rates consistent with the evaluated surface temperatures and explore the additional restrictions that could be set on the Vela’s mass and radius using different versions of the neutron star cooling theory.

Highlights

We reanalyze the observations of the X-ray surface emission of the Vela pulsar (PSR B0833-45) and evaluate its effective surface temperature Ts∞, mass M, radius R and the internal neutrino cooling rate using the cooling theory of neutron stars (NSs) [1]
There are a lot of X-ray observations of the Vela pulsar, but here we use only those performed by the Chandra space observatory in the two modes: HRC-S/LETG (ObsID 127 and 1852, taken on 28.01.00 and 12.01.01, respectively) and ACIS-S/HETG/CC (ObsID 131, taken on 11-12.10.99)
We have analyzed the X-ray spectrum of the Vela pulsar using the data of the Chandra observatory

Summary

Introduction

We reanalyze the observations of the X-ray surface emission of the Vela pulsar (PSR B0833-45) and evaluate its effective surface temperature Ts∞ (redshifted for a distant observer), mass M, radius R and the internal neutrino cooling rate using the cooling theory of neutron stars (NSs) [1]. The central black solid line shows the standard cooling [17] (of non-superfluid NSs with the modified Urca neutrino emission in the core and iron heat blanketing envelope). This curve is almost unaffected by the equation of state (EOS) of NS matter and NS mass (e.g., [18]).

Spectral Analysis of the Vela Pulsar

Vela’s Neutrino Cooling Rate

Conclusions