The topology and polarization of sub-beams associated with the `drifting' subpulse emission of pulsar B0943 + 10 - III. Analysis of Pushchino 103/40-MHz observations

Abstract

The rotating emission-beam system of pulsar B0943 + 10 was explored in Paper I of this series using Arecibo observations at 430 and 111 MHz and in Paper II using Gauribidanur 35-MHz data. Here, we have the opportunity to study simultaneous, dual-frequency observations carried out at the Pushchino Radio Astronomy Observatory some 10 yr ago at frequencies of 103 and 40 MHz. The apparent modulation periods (P3) and circulation times derived from the 11 d of observations seem to fall into two distinct ranges, apparently correlated with profile modal effects. The 103-MHz maps bear a strong resemblance to the 111-MHz Arecibo sequence studied in Paper I, but show a variety of sub-beam intensity patterns, whereas similar comments can be made about the 40-MHz maps in relation to the 35-MHz maps of Paper II. Most interesting here is the result that there is little correspondence between the sub-beam maps at the two frequencies. Only for two of the observations do we find a correspondence between the pairs: one of the `B'-mode sequences with an asymmetric pattern as well as a `Q'-mode sequence occurring immediately prior to a transition to the `B' mode. Finally, we find that our various `B'-mode observations vary markedly in their profile linear polarization. The strongest sequences suggest differing proportions of secondary polarization mode power.