SGRs and AXPs proposed as ancestors of the Magnificent seven

TL;DR

This paper proposes that SGRs, AXPs, and XDINs are related objects, with XDINs being descendants of SGRs and AXPs, explained through magnetic flux expulsion in quark stars rather than surface temperature correlations.

Contribution

It introduces a CFLQS model to explain neutron star observations, linking SGRs, AXPs, and XDINs as evolutionary stages of the same object.

Findings

CFLQS model explains magnetic and thermal properties better than previous models.

XDINs are likely descendants of SGRs and AXPs.

Magnetic flux expulsion accounts for heating in quark stars.

Abstract

The recently suggested correlation between the surface temperature and the magnetic field in isolated neutron stars does not seem to work well for SGRs, AXPs and X-ray dim isolated neutron stars (XDINs; specifically the Magnificent Seven or M7). Instead by appealing to a Color-Flavor Locked Quark Star (CFLQS) we find a more natural explanation. In this picture, the heating is provided by magnetic flux expulsion from a crust-less superconducting quark star. Combined with our previous studies concerning the possibility of SGRs, AXPs, and XDINs as CFLQSs, this provides another piece of evidence that these objects are all related. Specifically, we propose that XDINs are the descendants of SGRs and AXPs.