Magnetar-like activity from the central compact object in the SNR RCW103

TL;DR

This paper presents evidence that the central compact object in SNR RCW 103 exhibits magnetar-like activity, including a short X-ray burst and a hard X-ray tail, suggesting it is a magnetar with an unusually slow rotation period of 6.67 hours.

Contribution

It reports the discovery of magnetar-like behavior in the CCO of RCW 103 and interprets its long rotation period as a result of fallback accretion, a novel explanation for this peculiar object.

Findings

Detection of a magnetar-like short X-ray burst.

Discovery of a hard X-ray tail in the spectrum during outburst.

The 6.67 hr period is interpreted as the neutron star's rotation period.

Abstract

The 6.67 hr periodicity and the variable X-ray flux of the central compact object (CCO) at the center of the SNR RCW 103, named 1E 161348-5055, have been always difficult to interpret within the standard scenarios of an isolated neutron star or a binary system. On 2016 June 22, the Burst Alert Telescope (BAT) onboard Swift detected a magnetar-like short X-ray burst from the direction of 1E 161348-5055, also coincident with a large long-term X-ray outburst. Here we report on Chandra, NuSTAR, and Swift (BAT and XRT) observations of this peculiar source during its 2016 outburst peak. In particular, we study the properties of this magnetar-like burst, we discover a hard X-ray tail in the CCO spectrum during outburst, and we study its long-term outburst history (from 1999 to July 2016). We find the emission properties of 1E 161348-5055 consistent with it being a magnetar. However in this scenario, the 6.67 hr periodicity can only be interpreted as the rotation period of this strongly magnetized neutron star, which therefore represents the slowest pulsar ever detected, by orders of magnitude. We briefly discuss the viable slow-down scenarios, favoring a picture involving a period of fall-back accretion after the supernova explosion, similarly to what is invoked (although in a different regime) to explain the "anti-magnetar" scenario for other CCOs.