Evidence for 3XMM J185246.6+003317 as a massive magnetar with a low magnetic field

Understand

3XMM J185246.6+003317 is a transient magnetar located in the vicinity of the supernova remnant Kes\,79.

• So far, observations have only set upper limits to its surface magnetic field and spindown, and there is no estimate for its mass and radius.
• Using ray-tracing modelling and Bayesian inference for the analysis of several light curves spanning a period of around three weeks, we have found that it may be one of the most massive neutron stars to date.
• In addition, our analysis suggests a multipolar magnetic field structure with a subcritical field strength and a carbon atmosphere composition.