Gotthelf, EVZhang, WMarshall, FEMiddleditch, JWang, QD2024-04-262024-04-262002-01-01https://hdl.handle.net/20.500.14394/2636<p>This is the pre-published version harvested from ArXiv. The published version is located at <a href="http://www.aspbooks.org/a/volumes/article_details/?paper_id=25188">http://www.aspbooks.org/a/volumes/article_details/?paper_id=25188</a></p>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 Delta nu / nu = (1.90+-0.05) x 10-9 and Delta nudot / nudot = (8.5+-0.5) x 10-5. 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 10-10 Hz/s.Astrophysics and Astronomyarticle