A high-frequency survey of the galactic plane for young and distant pulsars

Abstract

A survey has been conducted for radio pulsars along the northern galactic plane at 1400 MHz. Using a fast sampling rate and relatively high radio frequency, this survey minimized the selection effects associated with high galactic background emission, interstellar dispersion and multipath scattering, all of which had seriously affected previous major surveys. As a result, the search was sensitive to distant and shorter period pulsars at low galactic latitude. A total of 61 pulsars were detected of which 40 were not previously known. Most of the objects are at low galactic longitudes |$( -{5}^{\circ } \lt{}l\lt{}40^{\circ })$| and have high dispersion measures, |$DM\gtrsim400 \,\text{cm}^{-3}$| pc, suggesting that, for the first time, the survey significantly penetrated the pulsar population in the inner Galaxy. The pulse periods and timing data presented in this paper show that the detected sample is nearly an order of magnitude younger than those objects discovered in previous all-sky surveys, the median age being only about 8 × 105 yr. Three of the new pulsars have characteristic ages of only 2 × 104 yr and yet none of these, or any of the other pulsars, appears to be associated with known supernova remnants. Four of the pulsars have suffered glitches since their discovery: one, PSR 1820 – 11, is a member of a highly eccentric binary system and PSR 1829 – 10 has a planet-sized companion. Many of the new pulsars have integrated pulse profiles which, even at high radio frequency, are broadened by interstellar scattering. This suggests that the lines of sight sample high levels of irregular ionization in the galactic plane at low z-distance.