Millisecond Pulsar Emission Altitude from Relativistic Phase Shift: PSR J0437-4715

Abstract

We have analyzed the profile of the millisecond pulsar PSR J0437-4715 at 1440 MHz by fitting the Gaussians to pulse components, and identified its 11 emission components. We propose that they form a emission beam with 5 nested cones centered on the core. Using the phase location of component peaks, we have estimated the aberration--retardation (A/R) phase shift. Due to A/R phase shift, the centroid of intensity profile and the inflection point of polarization angle swing are symmetrically shifted in the opposite directions with respect to the meridional plane, which is defined by the rotation and magnetic axes. By recognizing this fact, we have been able to locate the phase location of meridional plane and estimate the absolute altitude of emission of core and conal components relative to the neutron star center. Using the more exact expression for phase shift given recently by Gangadhara (2005), we find that the radio emission comes from a range of altitude starting from the core at 7% of light cylinder radius to outer most cone at 30%.