2004/03/09 by K. S. Cheng, L. Zhang, P. Leung +1
Physics and Astronomy · #Astrophysical Phenomena and Observations #Galactic plane #Galaxy #Millisecond pulsar #Pulsar #Pulsars and Gravitational Waves Research #Scientific Research and Discoveries #X-ray pulsar #astro-ph
paper · pdf · doi:10.1086/386537
published as Astrophys.J. 608 (2004) 418-426 · 24 pages, 21 figures, accepted to be published in ApJ
arxiv created 2004/03/09 · openalex publication_date 2004/06/07 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/06
We study the γ-ray emission properties of pulsars by using a new self-consistent outer gap model. The outer gap can exist in pulsars older than 1 million yr if the effect of magnetic inclination angle, as well as the average properties of the outer gap, are considered. The mature γ-ray pulsars, whose ages are between 0.3 and 3 million yr, are able to move up to high Galactic latitude. Moreover, their γ-ray luminosities are weaker, and their spectra are significantly softer than those of younger γ-ray pulsars in the Galactic plane. We use a Monte Carlo method to simulate the statistical properties of γ-ray pulsars in the Galaxy as well as in the Gould Belt. We find that γ-ray pulsars located at ∣ b ∣ < 5° and ∣ b ∣ > 5° have very different properties. High Galactic latitude γ-ray pulsars are dominated by mature pulsars with longer periods, weaker fluxes, and softer spectra. If the pulsar birth rates in the Galaxy and the Gould Belt are ~10 -2 and ~2 × 10 -5 yr -1 , respectively, there are 42 and 35 radio-quiet γ-ray pulsars for ∣ b ∣ < 5° and ∣ b ∣ > 5°, respectively. The number of radio-quiet γ-ray pulsars from the Gould Belt are 2 and 13 for ∣ b ∣ < 5° and ∣ b ∣ > 5°, respectively. We suggest that a good fraction of unidentified EGRET γ-ray sources may be these radio-quiet γ-ray pulsars. Furthermore, γ-ray pulsars located at ∣ b ∣ > 5° satisfy L γ ∝ L , whereas L γ ∝ L for γ-ray pulsars in the Galactic plane, where β ~ 0.6 and δ ~ 0.3, respectively.