A SEARCH FOR PULSAR COMPANIONS TO OB RUNAWAY STARS

We have searched for radio pulsar companions to 40 nearby OB runaway s tars. Observations were made at 575 and 770 MHz with the NRAO 140 foot (43 m) telescope. The survey was sensitive to long-period pulsars wit h flux densities of 1 mJy or more. No pulsar companions to OB runaways were discovered. One previously unknown pulsar was discovered, PSR J2 044+4614, while observing toward target O star ED +45 degrees 3260. Fo llow-up timing observations of the pulsar measured its position to hig h precision, revealing a 9' separation between the pulsar and the targ et star, unequivocally indicating they are not associated. The pulsar is ordinary, except that its dispersion measure, 315 pc cm(-3), is unu sually high given its Galactic longitude, I = 85 degrees. The nondetec tion of pulsars bound to target stars places an upper limit of 8% (95% confidence) for the fraction of runaway OB stars with pulsar companio ns detectable via pulsed radio emission by surveys such as ours. Assum ing standard models for the pulsar beaming fraction and luminosity fun ction, we conclude most OB runaways do not have pulsar companions.