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.

Dynamic emission properties of pulsars B0943+10 and B1822-09 - I. Comparison, and the discovery of a ‘Q’-mode precursor

“…One instance above occurs soon after B‐mode onset, while the other two follow it by about 90 min. In addition, evidence of a tertiary modulation in the form of a low‐frequency feature has been seen to occur several times in B‐mode PSs at low frequencies (Paper II; Rankin, Suleymanova & Deshpande 2003, Paper III) – and a single instance of a corresponding Q‐mode feature was identified at 327 MHz (Paper IV). All of these apparitions are consistent with a rotating‐carousel subbeam system that has two discrete states: either the ‘beamlet’ configuration is sufficiently disordered so that no primary (‘drift’) modulation is observed, or it is composed of just 20 evenly spaced beamlets.…”

The topology and polarization of subbeams associated with the ‘drifting’ subpulse emission of pulsar B0943+10 - V. A new look at the low-frequency burst-mode emission

“…The methods of Papers I and II were then applied to a unique set of simultaneous dual frequency observations at 103 and 40 MHz acquired at the Pushchino Radio Astronomy Observatory (PRAO) and the results reported in Paper III of the series (Rankin, Suleymanova & Deshpande 2003, hereafter Paper III). The intriguing correlation between the shapes of the B‐mode average profiles and their corresponding circulation times was identified.…”

Fluctuation properties and polar emission mapping of pulsar B0834+06 at decametre wavelengths

“…Deshpande & Rankin (1999; hereafter DR99), Deshpande & Rankin (2001; hereafter Paper I), Asgekar & Deshpande (2001; hereafter Paper II) and Rankin, Suleymanova & Deshpande (2003; hereafter Paper III) have reported detailed studies of drifting subpulses of B0943+10 at frequencies in the range 35–430 MHz. The studies led to the identification of a system of sub‐beams circulating around the magnetic axis of B0943+10 that was responsible for the observed steady drift pattern (see DR99).…”