| Abstract : | Pulsars are nature's laboratories for physics under extremely high gravitational and magnetic fields. Subpulse drifting in pulsars, where systematic shifts are observed in the pulse phases of substructures within the main pulse (i.e., subpulses) and nulling (where pulsar emission temporarily ceases), are the most promising phenomena to uncover the long-standing problem of pulsar emission. This phenomenon can potentially provide an essential key for unlocking the mystery of how pulsars work. Intending to investigate the underlying emission physics, we have undertaken phased-array observations of the pulsar PSR J1822-2256, simultaneously covering the 300-500 MHz and 550-750 MHz frequency bands using the upgraded Giant Metrewave Radio Telescope (uGMRT). We exploit the uGMRT's high sensitivity, wide bandwidths, and sub-array capabilities, presenting new results emerging from our investigation of frequency dependence of single-pulse properties for this pulsar. Our analysis indicates four distinct subpulse drifting modes of emission with several new features and real and pseudo nulls for this pulsar, further suggesting a clear modal dependence of inferred emission heights. We discuss the implications for the pulsar emission mechanism, the possible spark configuration, and the carousel rotation period for this pulsar over the observed drift modes. Finally, I will discuss some of the open questions and results that our study [Janagal et al. 2022, MNRAS, 509, 4573] presents, which can aid in understanding the pulsar emission process to greater depths. |
