Do OB Runaway Stars Have Pulsar Companions?
C. J. Philp, C. R. Evans (UNC-CH), P. J. T. Leonard (UMD), D. A. Frail (NRAO) We have conducted a VLA search for radio pulsars at the positions of 44 nearby OB runaway stars. The observations involved both searching images for point sources of continuum emission and a time series analysis. Our mean flux sensitivity at 1.4 GHz to pulsars slower than 50 ms was 0.2 mJy. No new pulsars were found in the survey. The size of the survey, combined with the high sensitivity of the observations, sets a significant constraint on the probability, f_p, of a runaway OB star having an observable pulsar companion. We find f_p \le 6.5% with 95% confidence, if the general pulsar luminosity function is applicable to OB star pulsar companions. If a pulsar beaming fraction of 1 øver 3 is assumed, then we estimate that fewer than 20% of runaway OB stars have neutron star companions, unless pulsed radio emission is frequently obscured by the OB stellar wind. Our result is consistent with the dynamical (or cl
