HI line measurements of pulsars towards the Gum nebula and the Carina arm

Abstract

We have observed 21-cm absorption and emission spectra in the direction of seven southern pulsars with the Parkes telescope in order to derive their kinematic distances and to study the interstellar medium. For the first time, we have successfully obtained H I absorption measurements for PSRs J0942-5552, J1048-5832, J1224-6424 and J1401-6357. We have also significantly improved the sensitivity and resolution on PSRs J0738-4042, J0837-4135 and J1157-6224, the spectra of which have been measured previously, and obtained the transverse velocities of PSRs J0837-4135 and J0942-5552 by analysing their scintillation properties. We show that the Taylor & Cordes distance model works reasonably well for pulsars located behind the Gum nebula. Following from our earlier work, we show further evidence for strong deviations from a simple Galactic rotation law in the velocities of the H I gas towards the Carina arm.