1. Department of Physics, North Carolina State University, Raleigh, North Carolina 27695-8202, USA
2. Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6354, USA

Correspondence to: John M. Blondin¹ Correspondence and requests for materials should be addressed to J.M.B. (Email: john_blondin@ncsu.edu).

Abstract

Rotation-powered radio pulsars are born with inferred initial rotation periods¹ of order 300 ms (some as short as 20 ms) in core-collapse supernovae. In the traditional picture, this fast rotation is the result of conservation of angular momentum during the collapse of a rotating stellar core. This leads to the inevitable conclusion that pulsar spin is directly correlated with the rotation of the progenitor star². So far, however, stellar theory has not been able to explain the distribution of pulsar spins, suggesting that the birth rotation is either too slow³ or too fast^{2, 4}. Here we report a robust instability of the stalled accretion shock in core-collapse supernovae that is able to generate a strong rotational flow in the vicinity of the accreting proto-neutron star. Sufficient angular momentum is deposited on the proto-neutron star to generate a final spin period consistent with observations, even beginning with spherically symmetrical initial conditions. This provides a new mechanism for the generation of neutron star spin and weakens, if not breaks, the assumed correlation between the rotational periods of supernova progenitor cores and pulsar spin.

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