Astronomy & Astrophysics Seminar: Evidence for the spin-kick alignment of pulsars from the statistics of their magnetic inclinations

Zoom: https://tau-ac-il.zoom.us/j/87230679135?pwd=Y1duRlArUkJwSnhaaXVscUU0azY3Zz09

Abstract:

Isolated neutron stars are thought to receive a natal kick velocity at birth that is nearly aligned with their spin axis. To date, observational evidence for this alignment has mostly come from polarisation studies. It shows the presence of a spin-kick correlation, but both aligned and orthogonal cases remain plausible. Direct confirmation of this alignment has been limited to a single source in a supernova remnant (PSR J0538+2817) whose three-dimensional velocity has been well constrained. In my talk, I will briefly review the phenomenon of pulsar spin-kick alignment and present new observational evidence for it that is independent of polarization.

If the three-dimensional velocities of radio pulsars are predominantly aligned with their spin axes, a systematic difference in the observed transverse velocities of pulsars with small and large magnetic obliquities (the angles between the magnetic and spin axes) would be expected. In particular, neutron stars with small obliquities should have systematically smaller and less scattered transverse velocities due to projection effects. In contrast, pulsars with large obliquities should have transverse velocities close to their true three-dimensional velocities. We found this effect after analysing a sample of 13 low and 25 high obliquity pulsars with known distances and proper motions. We also performed a detailed population synthesis of the isolated pulsars, considering the evolution of their viewing geometry and both isotropic and spin-aligned kick scenarios. Our results show that the observed split in the transverse velocity distributions is consistent with the spin-aligned kick model, but not the isotropic case.
 

Seminar Organizer: Dr. Jonathan Stern

Recording >