Main and interpulse interaction in PSRs J1842+0358 and J1926+0737: evidence for interpole communication

Astronomy &Astrophysics manuscript no. output ©ESO 2025 December 4, 2025 Main and interpulse interaction in PSRs J1842+0358 and J1926+0737: evidence for interpole communication X. Song 1, P. Weltevrede 2, J. van Leeuwen 1, G. Wright 2, and M. Keith 2 1ASTRON, the Netherlands Institute for Radio Astronomy, Oude Hoogeveensedijk 4,7991 PD Dwingeloo, The Netherlands e-mail: [email protected] 2Jodrell Bank Centre for Astrophysics, Department of Physics and Astronomy, The University of Manchester, Manchester, M13 9PL, UK Received; accepted ABSTRACT Our understanding of the elusive radio-pulsar emission mechanism would be deepened by determining the locality of the emission. Pulsars in which the two poles interact can potentially help solve this challenge. We here report the discovery of interaction of emission between the main and the interpulse in two pulsars – J1842+0358 and J1926+0737, based on FAST and MeerKAT data. When emission is bright in one pulse, it is dim in the other. Even when split in just 2 groups (strong versus weak) the anti-correlated brightness can change by a factor ≳2. Both sources furthermore show the same quasi-periodic modulation from the main and interpulse, at timescales exceeding 100 pulse periods. The longitude stationary modulation from at least one pulse suggests that it is a key signature for interpulse pulsars showing main and interpulse interaction. If the interaction happens within an isolated magnetosphere, without external influences, either communication between the opposite poles is required, or global changes drive both. This detailed study of these two sources was only made possible by improved sensitivity. The fact that both show two-pole modulation strongly suggests this is a general phenomenon in interpulse pulsars. In regular pulsars only one pole is visible, and a number of these show correlated changes between the profile and spin-down rate, that are also thought to be caused by global magnetospheric changes. Our results strengthen the case that such interactive magnetospheres are common to all pulsars. Key words. pulsars: individual: J1842+0358 – pulsars: individual: J1926+0737 This document provides the online materials of the manuscript “Main and interpulse interaction in PSRs J1842+0358 and J1926+0737: evidence for interpole communication”, which includes the full pulse stacks of PSRs J1842+0348 and J1926+0737 (as Fig. 3 and 11 in the main manuscript), in Appendices B and C, respectively. Appendix B: PSR J1842+0358 pulse stacks (online only) Appendix C: PSR J1926+0737 pulse stacks (online only) Article number, page 1 of 11 A&A proofs: manuscript no. output 72 80 88 96 104 Pulse longitude (deg) 0 200 400 600 800 1000 Pulse number (a) MP pulse stack 252 258 264 270 276 Pulse longitude (deg) (b) IP pulse stack 0 20 40 60 80 MP intensity (c) Sp intensity 0 10 20 30 40 MP intensity (d) Run. avg. intensity 8 0 8 16 24 IP intensity 5 0 5 10 15 IP intensity Fig. B.1: The first 1000 single pulses for PSR J1842+0358: pulse stacks (MP, IP) and intensities (single-pulse, running-averaged). (a) Pulse stack of the MP. The blue and green margin bars mark the bright pulses, based on the intensities of the single pulses (blue, left) or their running averages (green, right). (b) As (a) but for the IP, now with violet and brown for single-pulse or running-averaged intensities, respectively. The single pulse intensities of the MP and the IP are in (c), with the running averaged intensities plotted on top. Margin bars identical to the left of (a) and (b). The running averaged intensities of the MP and the IP plotted alone are in (d), along with the corresponding selected bars (the same as those on the right of (a) and (b)). Article number, page 2 of 11 X. Song et al.: MP-IP interaction in PSRs J1842+0358 and J1926+0737 72 80 88 96 104 Pulse longitude (deg) 1000 1200 1400 1600 1800 2000 Pulse number (a) MP pulse stack 252 258 264 270 276 Pulse longitude (deg) (b) IP pulse stack 0 40 80 120 160 MP intensity (c) Sp intensity 0 10 20 30 40 50 MP intensity (d) Run. avg. intensity 10 0 10 20 IP intensity 5 0 5 10 15 IP intensity Fig. B.2: Pulse stacks of the MP (first panel) and the IP (second panel) for pulse number 1000 to 2000 for PSR J1842+0358, and the corresponding single pulse (third panel) and running averaged intensities (fourth panel). See text for the explanation of the lines. Article number, page 3 of 11 A&A proofs: manuscript no. output 72 80 88 96 104 Pulse longitude (deg) 2000 2200 2400 2600 2800 3000 Pulse number (a) MP pulse stack 252 258 264 270 276 Pulse longitude (deg) (b) IP pulse stack 0 20 40 60 80 MP intensity (c) Sp intensity 015 30 45 60 MP intensity (d) Run. avg. intensity 10 0 10 20 30 IP intensity 0 6 12 18 IP intensity Fig. B.3: Pulse stacks of the MP (first panel) and the IP (second panel) for pulse number 2000 to 3000 for PSR J1842+0358, and the corresponding single pulse (third panel) and running averaged intensities (fourth panel). See text for the explanation of the lines. Article number, page 4 of 11 X. Song et al.: MP-IP interaction in PSRs J1842+0358 and J1926+0737 72 80 88 96 104 Pulse longitude (deg) 3000 3200 3400 3600 3800 4000 Pulse number (a) MP pulse stack 252 258 264 270 276 Pulse longitude (deg) (b) IP pulse stack 0 20 40 60 80 MP intensity (c) Sp intensity 0 10 20 30 40 50 MP intensity (d) Run. avg. intensity 8 0 8 16 IP intensity 5 0 5 10 15 IP intensity Fig. B.4: Pulse stacks of the MP (first panel) and the IP (second panel) for pulse number 3000 to 4000 for PSR J1842+0358, and the corresponding single pulse (third panel) and running averaged intensities (fourth panel). See text for the explanation of the lines. Article number, page 5 of 11 A&A proofs: manuscript no. output 72 80 88 96 104 Pulse longitude (deg) 4000 4100 4200 4300 4400 4500 4600 4700 4800 Pulse number (a) MP pulse stack 252 258 264 270 276 Pulse longitude (deg) (b) IP pulse stack 0 20 40 60 80 MP intensity (c) Sp intensity 8 16 24 32 40 MP intensity (d) Run. avg. intensity 10 0 10 20 30 IP intensity 404812 IP intensity Fig. B.5: Pulse stacks of the MP (first panel) and the IP (second panel) for pulse number 4000 to 4849 for PSR J1842+0358, and the corresponding single pulse (third panel) and running averaged intensities (fourth panel). See text for the explanation of the lines. Article number, page 6 of 11 X. Song et al.: MP-IP interaction in PSRs J1842+0358 and J1926+0737 90 96 102 108 114 Pulse longitude (deg) 0 200 400 600 800 1000 Pulse number (a) MP pulse stack 256 264 272 280 Pulse longitude (deg) (b) IP pulse stack 0 40 80 120 160 MP intensity (c) Sp intensity 0 20 40 60 MP intensity (d) Run. avg. intensity 20 0 20 40 60 IP intensity 8 0 8 16 24 IP intensity Fig. C.1: The first 1000 single pulses for PSR J1926+0737: pulse stacks (MP, IP) and intensities (single-pulse, running-averaged). (a) Pulse stack of the MP. The blue and green margin bars mark the bright pulses, based on the intensities of the single pulses (blue, left) or their running averages (green, right). (b) As (a) but for the IP, now with violet and brown for single-pulse and runningaveraged intensities, respectively. The single pulse intensities of the MP and the IP are in (c), with the running averaged intensities plotted on top. Margin bars identical to the left of (a) and (b). The running averaged intensities of the MP and the IP plotted alone are in (d), along with the corresponding selected bars (the same as those on the right of (a) and (b)). Article number, page 7 of 11 A&A proofs: manuscript no. output 90 96 102 108 114 Pulse longitude (deg) 1000 1200 1400 1600 1800 2000 Pulse number (a) MP pulse stack 256 264 272 280 Pulse longitude (deg) (b) IP pulse stack 0 40 80 120 160 MP intensity (c) Sp intensity 015 30 45 60 MP intensity (d) Run. avg. intensity 15 0 15 30 45 IP intensity 0 8 16 24 IP intensity Fig. C.2: Pulse stacks of the MP (first panel) and the IP (second panel) for pulse number 1000 to 2000 for PSR J1926+0737, and the corresponding single pulse (third panel) and running averaged intensities (fourth panel). See text for the explanation of the lines. Article number, page 8 of 11 X. Song et al.: MP-IP interaction in PSRs J1842+0358 and J1926+0737 90 96 102 108 114 Pulse longitude (deg) 2000 2200 2400 2600 2800 3000 Pulse number (a) MP pulse stack 256 264 272 280 Pulse longitude (deg) (b) IP pulse stack 0 60 120 180 240 MP intensity (c) Sp intensity 0 20 40 60 80 MP intensity (d) Run. avg. intensity 20 0 20 40 60 IP intensity 0 8 16 24 IP intensity Fig. C.3: Pulse stacks of the MP (first panel) and the IP (second panel) for pulse number 2000 to 3000 for PSR J1926+0737, and the corresponding single pulse (third panel) and running averaged intensities (fourth panel). See text for the explanation of the lines. Article number, page 9 of 11