Revisiting the radial distribution of pulsars in the Galaxy

Department of Astronomy & Space Sciences, Faculty of Arts & Sciences, Erciyes University, Talas Yolu, 38039 Kayseri, Turkey e-mail: yusifov;kucuk@erciyes.edu.tr

Received: 9 July 2003
Accepted: 31 March 2004

Abstract

The high sensitivity Parkes and Swinburne Multibeam pulsar surveys have nearly doubled the number of known pulsars and revealed many more distant pulsars with high dispersion measures. These data allow us to investigate in more detail the statistical parameters and distribution of pulsars, especially in the central regions of the Galaxy, which was almost impossible in previous low-frequency and less-sensitive surveys. To estimate the distances to pulsars we used the new NE2001 Galactic electron density model. We study the Galactic distribution of normal pulsars with 1400 MHz luminosities greater than 0.1 mJy kpc² refining the shape and parameters of the radial distribution of pulsars. The maximum galactocentric distribution of pulsars is located at 3.2 ± 0.4 kpc and the scale-length of this distribution is 3.8 ± 0.4 kpc for the assumed distances to the Galactic center  kpc. The surface density of pulsars near the Galactic center is equal to or slightly higher than that in the solar neighborhood. For observable normal pulsars with luminosities ≥0.1 mJy kpc², we also re-estimate their local surface density and birth-rate: 41 ± 5 pulsars kpc^-2 and 4.1 ± 0.5 pulsars kpc^-2 Myr^-1 respectively. For the total number of potentially observable pulsars in the Galaxy, we obtain (24 ± 3)  10³ and (240 ± 30)  10³ before and after applying beaming correction according the Tauris & Manchester ([CITE]) beaming model. Within the limits of errors of estimations these results are in close agreement with the results of the previous studies of Lyne et al. ([CITE]) (hereafter LML98). The dependence of these results on the NE2001 model and recommendations for further improvement of electron density distribution are discussed.