The Distance and Age of the SNR Kes 73 and AXP 1E 1841-045

TL;DR

This paper refines the distance to the supernova remnant Kes 73 and its associated AXP 1E 1841-045 using HI and CO spectra, leading to updated estimates of its age and X-ray luminosity.

Contribution

It provides a new distance estimate for Kes 73 and its AXP using radio observations, correcting previous limits and refining the system's age and luminosity.

Findings

Distance to Kes 73 is between 7.5 and 9.8 kpc.

Refined age of the SNR is 500 to 1000 years.

AXP X-ray luminosity is approximately 50% higher.

Abstract

We provide a new distance estimate to the supernova remnant (SNR) Kes 73 and its associated anomalous X-ray pulsar (AXP) 1E 1841-045. 21 cm HI images and HI absorption/ emission spectra from new VLA observations, and 13CO emission spectra of Kes 73 and two adjacent compact HII regions (G27.276+0.148 and G27.491+0.189) are analyzed. The HI images show prominent absorption features associated with Kes 73 and the HII regions. The absorption appears up to the tangent point velocity giving a lower distance limit to Kes 73 of 7.5 kpc, which has previously been given as the upper limit. Also, G27.276+0.148 and G27.491+0.189 are at the far kinematic distances of their radio recombination line velocities. There is prominent HI emission in the range 80--90 km/s for all three objects. The two HII regions show HI absorption at ~ 84 km/s, but there is no absorption in the Kes 73 absorption spectrum. This implies an upper distance limit of ~ 9.8 kpc to Kes 73. This corrected larger distance to Kes 73/ AXP 1E 1841-045 system leads to a refined age of the SNR of 500 to 1000 yr, and a ~ 50% larger AXP X-ray luminosity.