Central compact objects in Kes 79 and RCW 103 as "hidden" magnetars with crustal activity

TL;DR

This paper explores the crustal activity of 'hidden' magnetars in central compact objects, proposing that flux variations can reveal internal magnetic field dynamics, with some candidates showing constant flux possibly due to lower activity.

Contribution

It introduces a model linking flux variability in central compact objects to crustal activity of hidden magnetars, expanding the list of potential candidates.

Findings

CXO J1852.6+0040 shows constant flux, indicating lower crustal activity.

1E161348-5055's properties can be explained by magnetar-like crustal activity.

The study suggests some hidden magnetars may be in a high activity state during observations.

Abstract

We propose that observations of "hidden" magnetars in central compact objects can be used to probe crustal activity of neutron stars with large internal magnetic fields. Estimates based on calculations by Perna \& Pons (2011), Pons \& Rea (2012) and Kaminker et al. (2014) suggest that central compact objects, which are proposed to be "hidden" magnetars, must demonstrate flux variations on the time scale of months-years. However, the most prominent candidate for the "hidden" magnetars --- CXO J1852.6+0040 in Kes 79, -- shows constant (within error bars) flux. This can be interpreted by lower variable crustal activity than in typical magnetars. Alternatively, CXO J1852.6+0040 can be in a high state of variable activity during the whole period of observations. Then we consider the source 1E161348-5055 in RCW103 as another candidate. Employing a simple 2D-modeling we argue that properties of the source can be explained by the crustal activity of the magnetar type. Thus, this object may be supplemented for the three known candidates for the "hidden" magnetars among central compact objects discussed in literature.