Constraining pulsar and fast radio burst emission models by utilizing particle-in-cell simulations

• Applicant: Jan Benacek, Ph.D.
• Subject Area: Astrophysics and Astronomy
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 517091742

Despite the discovery of their radio signals in the 1960s, the mechanisms of pulsar coherent radio emissions, as well as of the recently discovered fast radio bursts (FRBs), remain unexplained. This is particularly due to the lack of quantitative investigation that would allow a comparison of the effectiveness of relevant plasma processes in neutron star magnetospheres. Common simplifications are the radiation of a single interaction-free oscillating charged particle and the neglect of nonlinear collective plasma phenomena, wave absorption in the emission region, and quantum electrodynamic (QED) effects.The project's objective is to quantitatively investigate the emission mechanisms of pulsars and FRBs to assess and constrain them in comparison with observed radiation. The planned particle-in-cell (PIC) simulations will quantitatively describe the nonlinear plasma evolution as well as the QED effects at kinetic scales at which the emission emerge. In the approach, four the most promising emission mechanisms may operate simultaneously: (i) The role of the widely discussed curvature emission (by turning on/off the centrifugal force), (ii) direct relativistic plasma emission by wave-wave interactions, (iii) linear acceleration and (iv) free-electron maser emissions via accelerated particles along and at an arbitrary angle to the magnetic field, respectively. For plausible plasma and magnetic field properties of neutron star magnetospheres, the spectrum, radiated power, directional characteristics, and polarization should be determined for these mechanisms.The innovative approach of this project is that the nonlinear interactions of the considered processes, whose relative importance and efficiency are disputable, are self-consistently included to allow quantitative, comparable predictions of the efficiency and relative importance of the considered emission mechanisms. The emission properties of the radiation mechanisms will be compared with those known from observations.

• DFG Programme: Research Grants