Timing noise, glitches and the braking index of PSR B0540-69

Abstract

We report a pulse-time history of PSR B0540-69 based on the analysis of an extended data set including ASCA. BeppoSAX and RXTE observations spanning a time interval of about 8 years. This interval includes also the epoch of the glitch episode reported by Zhang et al. (2001). Our analysis shows the presence of relevant timing noise and does not give clear evidence of the glitch occurrence. We performed an accurate evaluation of the main timing parameters. v, v̇ and v̈ and derived a mean braking index of n= 2.125 ± 0.001 quite different from the lower value found by Zhang et al. (2001), but in rather good agreement with several other values reported in the literature.