Variability of the High Magnetic Field X-Ray Pulsar PSR J1846-0258 Associated with the Supernova Remnant Kes 75 as Revealed by the Chandra X-Ray Observatory

Abstract

We present results from the archival Chandra observations of the 0.3 s X-ray pulsar PSR J1846?0258 associated with the supernova remnant (SNR) Kes 75. The pulsar has the highest spin-down luminosity ($d{E}$ -->$d{E}$ -->$d{E}$ --> = 8.3 ? 1036 ergs s -->?1) among all the high magnetic field pulsars (HBPs) and has been classified as a Crab-like pulsar despite its magnetic field (5 ? 1013 G) being above the quantum critical field. It is the only HBP described by a nonthermal Crab-like spectrum, powering a bright pulsar wind nebula (PWN). Our spectroscopic study shows evidence of spectral softening (photon index ? = 1.32 -->+ 0.08?0.09 −0.09+0.08--> to 1.97 -->+ 0.05?0.07 −0.07+0.05-->) and temporal brightening [unabsorbed flux Funabs = (4.3 ? 0.2) ? 10 -->?12 to -->2.7?0.2+0.1 ? 10 -->?11 ergs cm -->?2 s -->?1] of the pulsar by ~6 times from 2000 to 2006. The 0.5-10 keV luminosity of the pulsar at the revised distance of 6 kpc has also increased from LX = (1.85 ? 0.08) ? 1034 to 1.16 -->+ 0.03?0.07 −0.07+0.03--> ? 1035 ergs s -->?1, and the X-ray efficiency increased from 0.2% ? 0.01 -->% to 1.4 -->+ 0.04?0.08% −0.08+0.04-->. The observed X-ray brightening and softening of the pulsar suggests for the first time that this HBP is revealing itself as a magnetar.