X-ray folded light curves of PSR J1119−6127 in the 0.5–10.0 keV energy band from XMM-Newton. Credit: Wang et al., 2020.

Using various space observatories, astronomers have conducted multi-wavelength study of a high-magnetic-field pulsar known as PSR J1119−6127, which underwent an outburst in 2016. The results shed more light on the properties of this pulsar during the post-outburst period. The study is detailed in a paper published August 28 on arXiv.org.

Pulsars are highly magnetized, rotating neutron stars emitting a beam of electromagnetic radiation. They are usually detected in the form of short bursts of radio emission, however, some of them are also observed using optical, X-ray and gamma-ray telescopes.

PSR J1119−6127 was discovered in 2000 by the Parkes multibeam pulsar survey, likely associated with the supernova remnant G292.2-0.5 at a distance of about 27,400 light years. The pulsar has a spin period of 0.407 seconds, a characteristic age of some 1,600 years and spin-down power of approximately 2.3 undecillion erg/s.

In late July 2016, NASA's Fermi and Swift spacecraft detected magnetar-like X-ray outbursts of PSR J1119−6127 and also 13 short X-ray bursts. The that was released during this event was estimated to be at a level of around 1.0 tredecillion erg. To better understand the evolution of PSR J1119−6127 after the 2016 outburst, several teams of researchers started to monitor this .

One such team, led by Huihui Wang of the Huazhong University of Science and Technology in Wuhan, China, carried out a multi-wavelength (from radio to gamma-ray band) study of PSR J1119−6127. For this purpose, they used data from Fermi, Swift, ESA's X-ray Multi-Mirror Mission (XMM-Newton) and NASA's Nuclear Spectroscopic Telescope Array (NuSTAR).

"In this study, we have performed a multi-wavelength study for PSR J1119−6127 after its 2016 magnetar-like outburst," the astronomers wrote in the paper.

Before the 2016 outburst, the X-ray pulse peak of PSR J1119−6127 was aligned with its radio pulse peak. The study found no substantial shift between these peaks after the outburst. It was noted that the observed X-ray spectra of both on-pulse and off-pulse phases are well described by two blackbody components plus a power-law model.

In general, the radio and X-ray emission properties, as well as the spindown properties of PSR J1119−6127 after the 2016 outburst were found to be similar to those of the magnetar XTE J1810−197, which underwent an X-ray outburst in 2003. Wang's study revealed that the evolution of the timing solution, radio emission and X-ray emission properties of PSR J1119−6127 after its latest outburst are very similar to those of XTE J1810−197. However, the recovery time scale and released total energy are one or two orders of magnitude smaller in PSR J1119−6127.

When it comes to the GeV gamma-ray emission from PSR J1119−6127, the results indicate that it is slightly suppressed around the 2016 outburst. The GeV spectral characteristics after January 2017 (post-relaxation epoch) are consistent with that of the pre-outburst period. Moreover, the phase difference between the gamma-ray peak and radio peak in the post-relaxation stage is about 0.4, which is consistent with the measurement before the 2016 X-ray outburst.

Taking into account all the collected data, the astronomers concluded that the 2016 X-ray outburst probably caused a reconfiguration of the global magnetosphere of PSR J1119−6127and changed the structure of the open field line regions. They added that this reconfiguration continued for about a half-year after the .

More information: Wang et al., A multi-wavelength study of PSR J1119−6127 after 2016 outburst, arXiv:2008.12585 [astro-ph.HE] arxiv.org/abs/2008.12585