PSR J1840-1419: A very cool neutron star

TL;DR

This paper reports upper limits on X-ray emissions for three neutron stars, highlighting PSR J1840-1419 as one of the coolest known, and compares temperature constraints across different neutron star types.

Contribution

It provides new temperature upper limits for three neutron stars, including the coolest neutron star known, and contextualizes these limits within the broader neutron star population.

Findings

PSR J1840-1419 is among the coolest neutron stars known.

High magnetic field pulsars are not significantly hotter than lower magnetic field ones.

The paper summarizes temperature measurements and limits for rotation-driven neutron stars.

Abstract

We present upper limits on the X-ray emission for three neutron stars. For PSR J1840$-$1419, with a characteristic age of 16.5 Myr, we calculate a blackbody temperature upper limit (at 99% confidence) of $kT_{\mathrm{bb}}^{\infty}<24^{+17}_{-10}$ eV, making this one of the coolest neutron stars known. PSRs J1814$-$1744 and J1847$-$0130 are both high magnetic field pulsars, with inferred surface dipole magnetic field strengths of $5.5\times10^{13}$ and $9.4\times10^{13}$ G, respectively. Our temperature upper limits for these stars are $kT_{\mathrm{bb}}^{\infty}<123^{+20}_{-33}$ eV and $kT_{\mathrm{bb}}^{\infty}<115^{+16}_{-33}$ eV, showing that these high magnetic field pulsars are not significantly hotter than those with lower magnetic fields. Finally, we put these limits into context by summarizing all temperature measurements and limits for rotation-driven neutron stars.