http://arxiv.org/abs/2305.08920
Neutron stars are born out of core-collapse supernovae, and they are imparted natal kicks at birth as a consequence of asymmetric ejection of matter and possibly neutrinos. Unless the force resulting from the kicks is exerted exactly at their center, it will also cause the neutron star to rotate. In this paper, we discuss the possibility that neutron stars may receive off-center natal kicks at birth, which imprint a natal rotation. In this scenario, the observed pulsar spin and transverse velocity in the Galaxy are expected to correlate. We develop a model of the natal rotation imparted to neutron stars and constrain it by the observed population of pulsars in our Galaxy. At $90\%$ confidence, we find that the location of the off-center kick is $R_{\rm kick}=1.12^{+4.79}_{-0.97}$\,km. Our result is robust when considering pulsars with different observed periods, transverse velocities, and ages. Our constraint can be used as a guide for core-collapse simulations of massive stars.
G. Fragione and A. Loeb
Wed, 17 May 23
3/67
Comments: 5 pages, 2 figures, 1 table