The remarkable 2011 outburst of the magnetar Swift J1822.3-1606
Abstract
Energetic bursts in the X-ray/soft gamma ray band are often observed from magnetars (magnetic field in the range 10^{14} - 10^{15} G). The most energetic of these bursts,- the giant flares, have been observed only from a few sources and exhibit distinct observational characteristics. The 2011 outburst of the relatively low magnetic field magnetar Swift J1822.3-1606 was quite extraordinary due to the interesting timing features observed during this outburst. Periodic modulations at the pulsar spin period were clearly visible, which is a characteristic typical feature seen during the decaying tail of magnetar giant flares. We investigated the temporal variations of the X-ray emission during the early phases of this outburst. The hardness ratio (HR) was found to be strongly anti-correlated X-ray pulse profile intensity much alike that is observed in the case of giant flares. The evolution of the pulse profile morphology also showed a similar behaviour like that for the giant flares but on much longer time scales. The energy released during the entire outburst is comparable to the energy emitted in minutes during the decaying tail of the giant flares. Based on these similarities, we suggest that the same underlying mechanism is probably triggering both the outburst and the giant flares. We propose that the trapped fireball that develops in the magnetosphere at the onset of such energetic events, can radiate away efficiently in minutes in the case of the giant flares, whereas for Swift J1822.3-1606, the efficiency of radiation of the fireball is not as high and, therefore, lasts much longer displaying an outburst. Such a scenario is well supported by the existing theoretical models of magnetars.
- Publication:
-
41st COSPAR Scientific Assembly
- Pub Date:
- July 2016
- Bibcode:
- 2016cosp...41E.315C