Hiccups in the night: X-ray monitoring of the two Crab-like LMC pulsars

We are undertaking an extensive X-ray monitoring campaign of the two Crab-like pulsars in the Large Magellanic Clouds, PSR B0540-69 and PSR J0537-6910. We present our current phase-connected timing analysis derived from a set of 50 pointed X-ray observations spanning several years. From our initial 1.2 yr monitoring program of the young 50 ms pulsar PSR B0540-69, we find the first compelling evidence for a glitch in its rotation. This glitch is characterized by dv / v = 1.90 +/- 0.05 X 10E-9 and $dvdot/ vdot = (8.5 +/- 0.5 X 10E-5. Taking into account the glitch event, we derive a braking index of n = 1.81 +/- 0.07, significantly lower than previous reported. For the 16 ms pulsar, PSR J0537-6910, we recorded 6 large glitch events during a period of nearly 3 years, the highest rate of all known Crab-like systems. Despite the extreme timing activity, the long term spin-down of this pulsar continues to average -1.9743 X 10E-10 Hz/s.