Phase-resolved Spectroscopic Imaging of the Crab Pulsar

摘要

High time resolution spectroscopic imaging of the Crab pulsar across the optical wave band has been undertaken utilizing the 4 m Mayall telescope at Kitt Peak National Observatory. The 33.51 ms period of the pulsar was split into 723.7 time slices of 46.3 μs and a spectrum within each slice acquired. These data have allowed analysis of both the light curve as a function of wavelength and the spectrum as a function of phase position. Wavelength-dependent changes in phase position for both emission peaks have been found, and these appear to be uncorrelated. Related to these changes are phase position-dependent variations in the spectral index, and these have been measured, the shapes being in agreement with previously published data. Also related are energy-dependent changes in the FWHMs. In addition, we find, in support of previously published data, that the fluence of Peak 2 relative to Peak 1 decreases with increasing wavelength. These results then challenge the validity of currently existing models for pulsar emission.