Observational Constraints on the Pulsar Wind Model: The Cases of Crab and Vela

Abstract

Abstract As is well known, pulsars are extremely stable rotators. However, although slowly, they spindown thanks to brake mechanisms, which are in fact still a subject of intense investigation in the literature. Since pulsars are usually modeled as highly magnetized neutron stars that emit beams of electromagnetic radiation out of their magnetic poles, it is reasonable to consider that the spindown has to do with a magnetic brake. Although an interesting and simple idea, a pure magnetic brake is not able to adequately account for the spindown rate. Thus, many alternative spindown mechanisms appear in the literature, among them the pulsar wind model, where the wind of particles coming from the pulsar itself can carry part of its rotational kinetic energy. Such a spindown mechanism depends critically on three parameters, namely, the dipole magnetic field (B), the angle between the magnetic and rotation axes (ϕ), and the density of primary particles (ζ) of the pulsar’s magnetosphere. Differently from a series of articles in this subject, we consider for the first time in the literature a statistical modeling that includes a combination of a magnetic dipole and wind brakes. As a result, we are able to constrain the above referred parameters in particular for Crab and Vela pulsars.