A Magnetar-Like Outburst From a High-B Radio Pulsar

Abstract

Radio pulsars are believed to have their emission powered by the loss of rotational kinetic energy. By contrast, magnetars show intense X-ray and γ-ray radiation whose luminosity greatly exceeds that due to spin down and magnetar luminosity is believed to be powered by intense internal magnetic fields. A basic prediction of this picture is that radio pulsars of high magnetic field should show magnetar-like emission. Here we report on a magnetar-like X-ray outburst from the radio pulsar PSR J1119-6127, heralded by two short bright X-ray bursts on 2016 July 27 and 28. Using target of opportunity data from the Swift X-ray Telescope and NuSTAR, we show that this pulsar's flux has brightened by a factor of >160 in the 0.5-10 keV band, and that its previously soft X-ray spectrum has undergone a strong hardening with strong pulsations appearing for the first time above 2.5 keV, with phase-averaged emission detectable up to 25 keV. By comparing Swift-XRT and NuSTAR timing data with a preoutburst ephemeris derived from Fermi Large Area Telescope data, we find that the source has contemporaneously undergone a large spin-up glitch of amplitude n n D =´-5.74 8 10 6 ( ) . The collection of phenomena observed thus far in this outburst strongly mirrors those in most magnetar outbursts and provides an unambiguous connection between the radio pulsar and magnetar populations.

Post-Outburst Radio Observations of the High Magnetic Field Pulsar PSR J1119-6127

“…This was previously suggested because of its unusual pulsed X-ray emission (Gonzalez et al 2005), which was hard to reconcile with the thermal emission from the rotation-powered pulsar. This is now dramatically confirmed by clear magnetar-like outbursts (Archibald et al 2016a;Göğüş et al 2016). PSRJ1119-6127 now joins PSRJ1846-0258 as a high magnetic field pulsar with transient magnetar-like behavior (Kaspi 2010;Ng & Kaspi 2011).…”

“…Such behavior is unlikely to be powered solely by rotation, but also by the release of stored magnetic energy (Archibald et al 2016a). This was previously suggested because of its unusual pulsed X-ray emission (Gonzalez et al 2005), which was hard to reconcile with the thermal emission from the rotation-powered pulsar.…”

“…A glitch was reported by Archibald et al (2016b) using Swift XRT, NuSTAR, and Fermi Large Area Telescope (LAT) data. Archibald et al (2016a) observed spectral hardening of PSRJ1119-6127 following the highenergy outburst, which is suggestive of magnetar-like emission, as in the case of the rotation-powered pulsar PSRJ1846-0258 (Gavriil et al 2008). Göğüş et al (2016) uncovered a total of 12 hard X-ray bursts during 2016 July 26-28 using Fermi GBM and Swift XRT observations and carried out spectral and temporal analyses of the emission.…”

“…Periodicity searches were performed using the PRESTO pulsar search package (Ransom 2001) near the spin period of the pulsar with an updated ephemeris provided by Archibald et al (2016a). We observed bright pulsed emission at S-band during epochs3 and4 after the reported reactivation of radio emission at L-band (Burgay et al 2016b).…”

The Braking Index of a Radio-Quiet Gamma-Ray Pulsar

“…Such a high magnetic field could affect a pulsar's high-energy emission, however both pulsars have gamma-ray spectra that are typical of young pulsars (Abdo et al 2013). Given their similar magnetic fields, one may expect PSR J1208−6238 to exhibit similar magnetar-like activity as was recently seen from PSR J1119−6127 (Archibald et al 2016a;Gögüş et al 2016). However, no X-ray emission has been detected from PSR J1208−6238 (Stroh & Falcone 2013).…”