Radio emission region exposed: courtesy of the double pulsar

Abstract

The double pulsar system PSR J0737-3039A/B offers exceptional possibilities for detailed probes of the structure of the pulsar magnetosphere, pulsar winds and relativistic reconnection. We numerically model the distortions of the magnetosphere of pulsar B by the magnetized wind from pulsar A, including effects of magnetic reconnection and of the geodetic precession. Geodetic precession leads to secular evolution of the geometric parameters and effectively allows a 3D view of the magnetosphere. Using the two complimentary models of pulsar B's magnetosphere, adapted from the Earth's magnetosphere models by Tsyganenko (ideal pressure confinement) and Dungey (highly resistive limit), we determine the precise location and shape of the coherent radio emission generation region within pulsar B's magnetosphere. We successfully reproduce orbital variations and secular evolution of the profile of B, as well as subpulse drift (due to reconnection between the magnetospheric and wind magnetic fields), and determine the location and the shape of the emission region. The emission region is located at about 3750 stellar radii and has a horseshoe-like shape, which is centered on the polar magnetic field lines. The best fit angular parameters of the emission region indicate that radio emission is generated on the field lines which, according to the theoretical models, originate close to the poles and carry the maximum current. We resolved all but one degeneracy in pulsar B's geometry. When considered together, the results of the two models converge and can explain why the modulation of B's radio emission at A's period is observed only within a certain orbital phase region. Our results imply that the wind of pulsar A has a striped structure only 1000 light cylinder radii away. We discuss the implications of these results for pulsar magnetospheric models, mechanisms of coherent radio emission generation, and reconnection rates in relativistic plasma.

FRB Periodicity: Mild Pulsars in Tight O/B-star Binaries

“…We conclude that even in the tightest orbit case of geodetically induced precession, the powers expected due to the interaction of the binaries are very small. (Lyutikov 2004;Lyutikov & Thompson 2005;Lomiashvili & Lyutikov 2014, Note, that binary pulsar PSR0737B that shows strong magnetospheric interaction is/was an exceptionally weak pulsar -it cannot not be used as an model for FRBs, the most powerful radio emitters.). Hence we conclude that binarity is not a cause of FRB emission.…”

Coherent emission mechanisms in astrophysical plasmas

“…One approach to constraining the source region is to appeal to retardation and aberration effects (Gupta and Gangadhara, 2003), but the results are not compelling. The opinion that the emission comes from high in the magnetosphere is supported by direct evidence from the double-pulsar system (Lyutikov, 2010;Lomiashvili and Lyutikov, 2014). -What drives the coherent emission?…”

Consequences of a strong phase transition in the dense matter equation of state for the rotational evolution of neutron stars

“…Pulsar B has become invisible to terrestrial observers in March 2008 because its beam wandered out of our line of sight as a consequence of the geodetic precession effect (Perera et al 2010). It may reappear as late as in 2034 (or later), depending on the model of the pulsar magnetosphere (see, e.g., Lomiashvili & Lyutikov 2014). Since the mass of pulsar A has been accurately determined, a measurement of its moment of inertia through the spin-orbit momentum coupling would allow us to constrain the radius and hence the EOS (Lattimer & Schutz 2005).…”