Parkes observations for project P1078 semester 2020OCTS_04

Black-Widow (BW) millisecond pulsars (MSPs) form a special subclass of MSPs having a low mass companion (~0.01-0.05 solar mass) in compact binary orbit with orbital period < 10 hours. Material blown from the companion by relativistic pulsar wind causes frequency dependent eclipses of the pulsar radio emission. Among these known eclipsing BW MSPs we have chosen three relatively bright objects which show eclipses at relatively higher radio frequencies. We request 30 hours observing time to observe these pulsars with Parkes UWL receiver in 700-4032 MHz to achieve the following science goals,\r\n i) With wideband observations of these pulsars we will apply a technique of modelling the eclipse phase spectra (already demonstrated by us) in optically thick to thin transition state (optical depth ~1), which will in turn allow to directly probe to the eclipse material.\r\nii) Simultaneous polarisation observations will allow us to predict the magnetic field strength in the eclipse boundaries through measurements of the rotation measure . Derived magnetic field strengths at the eclipse boundaries will be compared with the values from modelling the eclipse phase spectra. This will allow us to solve the existing puzzle of few orders of magnitude lower magnetic field strength at eclipse boundaries to withstand the pulsar wind ram pressure.\r\niii) Modelling the spectra at different orbital phases over the eclipse will allow us to probe the eclipse material properties and eclipse mechanism at different orbital phases, which is a new way to probe the pulsar and stellar wind interaction.