Discovery of High-Energy Gamma-Ray Pulsations from PSR J2021+3651 with AGILE

Abstract

Discovered after the end of the Compton Gamma-Ray Observatory mission, the radio pulsar PSR J2021+3651 was long considered a likely counterpart of the high-energy gamma-ray source 2CG 075+00 = 3EG J2021+3716 = GeV J2020+3658, but it could not be confirmed due to the lack of a contemporaneous radio pulsar ephemeris to fold the sparse, archival gamma-ray photons. Here, we report the discovery of gamma-ray pulsations from PSR J2021+3651 in the 100-1500 MeV range using data from the AGILE satellite gathered over 8 months, folded on a densely sampled, contemporaneous radio ephemeris obtained for this purpose at the Green Bank Telescope. The gamma-ray pulse consists of two sharp peaks separated by 0.47+/-0.01 cycles. The single radio pulse leads the first gamma-ray peak by 0.165+/-0.010 cycles. These properties are similar to those of other gamma-ray pulsars, and the phase relationship of the peaks can be interpreted in the context of the outer-gap accelerator model for gamma-ray emission. Pulse-phase resolved images show that there is only one dominant source, AGL J2020.5+3653 = PSR J2021+3651 in the region previously containing confused sources 3EG J2021+3716 and 3EG J2016+3657.

4 pages, 4 figures. to appear in The Astrophysical Journal Letters

References in corpus (4)

• TeV Gamma-Ray Sources from a Survey of the Galactic Plane with Milagro
• Discovery of TeV Gamma-Ray Emission from the Cygnus Region of the Galaxy
• Fitting Pulsar Wind Tori. II. Error Analysis and Applications
• Rings and Jets around PSR J2021+3651: the `Dragonfly Nebula'

Cited by in corpus (11)

• Milagro Observations of Multi-TeV Emission from Galactic Sources in the Fermi Bright Source List
• The Third Fermi Large Area Telescope Catalog of Gamma-ray Pulsars
• Discovery of new gamma-ray pulsars with AGILE
• Pulsed Gamma-rays from PSR J2021+3651 with the Fermi Large Area Telescope
• Pulsed Gamma-rays from the millisecond pulsar J0030+0451 with the Fermi Large Area Telescope
• Discovery of Pulsations from the Pulsar J0205+6449 in SNR 3C 58 with the Fermi Gamma-Ray Space Telescope
• The Second AGILE Catalog of Gamma-Ray Sources
• Study of the gamma-ray source 1AGL J2022+4032 in the Cygnus Region
• A 350-MHz Green Bank Telescope Survey of Unassociated Fermi LAT Sources: Discovery and Timing of Ten Millisecond Pulsars
• High-Resolution Radio Study of the Dragonfly Nebula
• Pulsar Simulations for the Fermi Large Area Telescope