Single-pulse Emissions of PSRs J1611−0114 and J1617+1123

In this paper, the emissions from two pulsars, PSRs J1611−0114 and J1617+1123, were investigated using the Five-hundred-meter Aperture Spherical radio Telescope (FAST) operating at a central frequency of 1250 MHz. Observations began in December 2020, with 26 observing sessions for each pulsar. The average pulse profile of PSR J1611−0114 shows two components, the first of which is relatively weak in intensity. The two-dimensional pulse stack shows an obvious nulling phenomenon, with an estimated nulling fraction (NF) of 40.1%±5.5%. The durations of the nulls and bursts consist with power-law distributions, and no periodic nulling phenomenon is found. PSR J1617+1123 shows that the average pulse profile is composed of four components. The peak intensity of the fourth component varies significantly, causing the unstable integrated profile. In addition, the modulation characteristics of J1611−0114 and J1617+1123 were studied by analyzing the modulation index, longitude resolved fluctuation spectrum (LRFS) and two-dimensional fluctuation spectrum (2DFS) using the software PSRSALSA. It was found that the two pulsars exhibit intensity modulation. Specially J1611−0114 shows even-odd modulation, with the modulation period of approximately two pulses. The modulation period of J1617+1123 is relatively broad. There is an obvious subpulse drift phenomenon, and the value of P2 is ∼ 0.125c/P0, corresponding to 12 pulse longitude bins, and the drift rate (P2/P3) is about 0.29.