Burst and Outburst Characteristics of Magnetar 4U 0142+61

TL;DR

This study compiles and analyzes 27 bursts from magnetar 4U 0142+61 across three active episodes, revealing their morphological similarities to typical magnetar bursts, but with lower energies and the discovery of a thermal tail emission with associated X-ray bursts.

Contribution

The paper provides the most comprehensive burst sample from 4U 0142+61, including the first detection of a thermal tail emission and phase-aligned X-ray bursts, offering new insights into burst mechanisms.

Findings

Bursts resemble typical short magnetar bursts but are less energetic.

Detected a thermal tail emission cooling over minutes after a burst.

Found phase-aligned X-ray bursts possibly linked to the tail emission.

Abstract

We have compiled the most comprehensive burst sample from magnetar 4U 0142+61, comprising 27 bursts from its three burst-active episodes in 2011, 2012 and the latest one in 2015 observed with Swift/BAT and Fermi/GBM. Bursts from 4U 0142+61 morphologically resemble typical short bursts from other magnetars. However, 4U 0142+61 bursts are less energetic compared to the bulk of magnetar bursts. We uncovered an extended tail emission following a burst on 2015 February 28, with a thermal nature, cooling over a time-scale of several minutes. During this tail emission, we also uncovered pulse peak phase aligned X-ray bursts , which could originate from the same underlying mechanism as that of the extended burst tail, or an associated and spatially coincident but different mechanism.