PSR J2021+3651: A young radio pulsar coincident with an unidentified egret γ-ray source

Mallory S.E. Roberts, Jason W.T. Hessels, Scott M. Ransom, Victoria M. Kaspi, Paulo C.C. Freire, Fronefield Crawford, Duncan R. Lorimer

Research output: Contribution to journalArticlepeer-review


We report on a deep search for radio pulsations toward five unidentified ASCA X-ray sources coincident with EGRET γ-ray sources. This search has led to the discovery of a young and energetic pulsar using data obtained with the new Wideband Arecibo Pulsar Processor. PSR J2021+3651 is likely associated with the X-ray source AX J2021.1+3651, which in turn is likely associated with the COS B high-energy γ-ray source 2CG 075+00, also known as GeV J2020+3658 or 3EG J2021+3716. PSR J2021+3651 has a rotation period of P ∼ 104 ms and P ̇ ∼ 9.6 × 10-14, implying a characteristic age of τ c ∼ 17 kyr and a spin-down luminosity of Ė ∼ 3.4 × 1036 ergs s-1. The dispersion measure DM ∼ 371 pc cm-3 is by far the highest of any observed pulsar in the Galactic longitude range 55° < l < 80°. This DM suggests a distance d ≳ 10 kpc and a high γ-ray efficiency of ∼15%, but the true distance may be closer if there is a significant contribution to the DM from excess gas in the Cygnus region. The implied luminosity of the associated X-ray source suggests the X-ray emission is dominated by a pulsar wind nebula unresolved by ASCA.

Original languageEnglish (US)
Pages (from-to)L19-L22
JournalAstrophysical Journal
Issue number1 II
StatePublished - Sep 20 2002


  • Gamma rays: observations
  • Pulsars: general
  • Stars: neutron

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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