Theory of pulsar magnetosphere and wind

Abstract

Neutron stars are fascinating astrophysical objects immersed in strong gravitational and electromagnetic fields, at the edge of our current theories. These stars manifest themselves mostly as pulsars, emitting a timely very stable and regular electromagnetic signal. Even though discovered almost fifty years ago, they still remain mysterious compact stellar objects. In this review, we summarize the most fundamental theoretical aspects of neutron star magnetospheres and winds. The main competing models explaining their radiative properties like multi-wavelength pulse shapes and spectra and the underlying physical processes such as pair creation and radiation mechanisms are scrutinized. A global but still rather qualitative picture slowly emerges thanks to recent advances in numerical simulations on the largest scales. However considerations about pulsar magnetospheres remain speculative. For instance, the exact composition of the magnetospheric plasma is not yet known. Is it solely filled with a mixture of e ± leptons or does it contain a non-negligible fraction of protons and/or ions? Is it almost entirely filled or mostly empty except for some small anecdotal plasma filled regions? Answers to these questions will strongly direct the description of the magnetosphere to seemingly contradictory results leading sometimes to inconsistencies. Nevertheless, accounts are given as to the latest developments in the theory of pulsar magnetospheres and winds, the existence of a possible electrosphere and physical insight obtained from related observational signatures of multi-wavelength pulsed emission.

Meterwavelength Single-pulse Polarimetric Emission Survey. III. The Phenomenon of Nulling in Pulsars

“…It has been reported (e.g. most recently by Philippov et al 2015;Pétri 2016, and references therein) that a sufficient supply of charges from the neutron star surface as well as from the pair production results in transition from a charge separated magnetosphere to a force-free magnetosphere. The charge separated magnetosphere corresponds to the case where charged particles are trapped in charge separated zones which co-rotate with the star.…”

Radiative pulsar magnetospheres: aligned rotator

“…Its charge density ρe is deduced from Maxwell-Gauss law. Following the derivation given by Pétri (2016), the radiative current density j is expressed solely in terms of the electromagnetic field via…”

Electrodynamics of Pulsar Magnetospheres

“…The topic has been discussed in many reviews, e.g. by Arons (1979); Michel (2004) and recently by Arons (2009Arons ( , 2012; Spitkovsky (2011); Bühler and Blandford (2014); Beskin et al (2015); Grenier and Harding (2015); Pétri (2016). We focus on the pulsar itself, i.e.…”