Wide band simultaneous multi-frequency single pulse study of PSR J1822–2256 with upgraded GMRT

Abstract

We present simultaneous multi-frequency observations of PSR J1822–2256 for the first time, utilizing the unique capabilities of upgraded Giant Meterwave Radio Telescope (uGMRT). No emission is detected in about 10 % of pulses. At least two drift modes and a possibly third rare mode, occur for 66, 21 and 2 % pulses respectively (P3 ~ 17, 7.5 and 5 P0 respectively). The three drift modes and the nulls occur concurrently from 250 to 1500 MHz. Modal average profiles are distinct with their widths increasing with drift rate. These sub-pulse drift related profile mode-changes can provide independent probes of beam geometry and polar gap physics.

Independent discovery of a nulling pulsar with unusual sub-pulse drifting properties with the Murchison Widefield Array

“…The drift rate, however, is highly variable, as can be seen in the example pulse stacks in Fig 4 . Sometimes the drift rate appears to change abruptly, reminiscent of the drift mode changes observed in several other pulsars (e.g. Kloumann & Rankin 2010;Rankin et al 2013;Joshi et al 2017;McSweeney et al 2019). However, apart from these abrupt changes, the drift rate is seen to evolve gradually, as does the "vertical spacing" between them, denoted by P 3 (see, e.g., the sequences marked "A1" in Fig 4).…”

“…In the presence of aliasing, multiple drift modes can be explained if the number of sparks in the carousel changes, even if the carousel speed itself doesn't change. This idea has been invoked to explain the multiple drift rates of B1918+19 (Rankin et al 2013), B1819−22 (Joshi et al 2017;Janagal et al 2022), andB0031−07 (Mc-Sweeney et al 2019). Aliasing can also "amplify" the variability of the drift rate if the ratio of stellar rotation and carousel rotation is very close to a ratio of small integers.…”