PSR J2021+3651: A new γ-ray pulsar candidate

M. S.E. Roberts, J. W.T. Hessels, S. M. Ransom, V. M. Kaspi, P. C.C. Freire, F. Crawford, D. R. Lorimer

Research output: Contribution to journalArticlepeer-review


The COS B high energy γ-ray source 2CG 075+00, also known as GeV J2020+3658 or 3EG J2021+3716, has avoided identification with a low energy counterpart for over 20 years. We present a likely identification with the discovery and subsequent timing of a young and energetic pulsar, PSR J2021+3651, with the Wideband Arecibo Pulsar Processor at the Arecibo Observatory. PSR J2021+3651 has a rotation period P ∼ 104 ms and Ṗ ∼ 9.6 × 10 -14 , implying a characteristic age τ c ∼ 17 kyr and a spin-down luminosity Ė ∼ 3.4 × 10 36 erg s -1 . The pulsar is also coincident with the ASCA source AX J2021.1+3651. The implied luminosity of the associated X-ray source suggests the X-ray emission is dominated by a pulsar wind nebula unresolved by ASCA. The pulsar's unexpectedly high dispersion measure (DM ∼ 371 pc cm -3 ) and the d ≥ 10 kpc DM distance pose a new question: is PSR J2021+3651 an extremely efficient γ-ray pulsar at the edge of the Galaxy? This is a question for AGILE and GLAST to answer.

Original languageEnglish (US)
Pages (from-to)577-580
Number of pages4
JournalAdvances in Space Research
Issue number4
StatePublished - 2004


  • GeV 2020+3658
  • High energy γ-rays
  • PSR J2021+3651
  • Pulsars
  • Young pulsar
  • γ-ray pulsar

ASJC Scopus subject areas

  • Aerospace Engineering
  • Astronomy and Astrophysics
  • Geophysics
  • Atmospheric Science
  • Space and Planetary Science
  • General Earth and Planetary Sciences


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