Arecibo timing and single-pulse observations of 17 pulsars

Abstract

We report on timing and single-pulse observations of 17 pulsars discovered at the Arecibo Observatory. The highlights of our sample are the recycled pulsars J1829+2456, J1944+0907 and the drifting subpulses observed in PSR J0815+0939. For the double neutron star binary J1829+2456, in addition to improving upon our existing measurement of relativistic periastron advance, we have now measured the pulsar's spin-period derivative. This new result sets an upper limit on the transverse speed of 120 km s−1 and a lower limit on the characteristic age of 12.4 Gyr. From our measurement of proper motion of the isolated 5.2-ms pulsar J1944+0907, we infer a transverse speed of 188 ± 65 km s−1. This is higher than that of any other isolated millisecond pulsar. An estimate of the speed, using interstellar scintillation, of 235 ± 45 km s−1 indicates that the scattering medium along the line of sight is non-uniform. We discuss the drifting subpulses detected from three pulsars in the sample, in particular the remarkable drifting subpulse properties of the 645-ms pulsar J0815+0939. Drifting is observed in all four components of the pulse profile, with the sense of drift varying among the different components. This unusual ‘bi-drifting’ behaviour challenges standard explanations of the drifting subpulse phenomenon.