Are Supershells Powered by Multiple Supernovae? Modeling the Radio Pulsar Population Produced by OB Associations

Abstract

Traditional searches for radio pulsars have targeted individual small regions such as supernova remnants or globular clusters or have covered large contiguous regions of the sky. None of these searches have been specifically directed toward giant supershells, some of which are likely to have been produced by multiple supernova (SN) explosions from an OB association. Here we perform a Monte Carlo simulation of the pulsar population associated with supershells powered by multiple SNe. We predict that several tens of radio pulsars associated with the largest Galactic supershells (with kinetic energies 1053 ergs) could be detected with current instruments and a few pulsars associated with the smaller supershells. We test these predictions for some of the supershells that lie in regions covered by past pulsar surveys. For the smaller supershells, our results are consistent with the few detected pulsars per bubble. For the giant supershell GSH 242-03+37, we find the multiple SN hypothesis inconsistent with current data at the ~95% level. We stress the importance of undertaking deep pulsar surveys in correlation with supershells. Failure to detect any pulsar enhancement in the largest of them would put serious constraints on the multiple SN origin for them. Conversely, the discovery of the pulsar population associated with a supershell would allow a different, independent approach to the study of pulsar properties.