We report on the aftermath of a magnetar outburst from the young , high-magnetic-field radio pulsar PSR J1119 - 6127 that occurred on 2016 July 27 .
We present the results of a monitoring campaign using the Neil Gehrels Swift X-ray Telescope , NuSTAR , and XMM-Newton .
After reaching a peak luminosity of \sim 300 times the quiescent luminosity , the pulsar ’ s X-ray flux declined by factor of \sim 50 on a time scale of several months .
The soft X-ray spectra are well described by a blackbody and a hard power-law tail .
After an initial rapid decline during the first day of the outburst , we observe the blackbody temperature rising from kT = 0.9 keV to 1.05 keV during the first two weeks of the outburst , before cooling to 0.9 keV .
During this time , the blackbody radius decreases monotonically by a factor of \sim 4 over a span of nearly 200 days .
We also report a heretofore unseen highly pulsed hard X-ray emission component , which fades on a similar timescale to the soft X-ray flux , as predicted by models of relaxation of magnetospheric current twists .
The previously reported spin-up glitch which accompanied this outburst was followed by a period of enhanced and erratic torque , leading to a net spin-down of \sim 3.5 \times 10 ^ { -4 } Hz , a factor of \sim 24 over-recovery .
We suggest that this and other radiatively loud magnetar-type glitch recoveries are dominated by magnetospheric processes , in contrast to conventional radio pulsar glitch recoveries which are dominated by internal physics .