COMPTEL detection of the high-energy gamma-ray source 2CG 135+01

Academic Article


  • We present an analysis of COMPTEL observations made between November 1991 and May 1994 of 2CG 135+01, a bright gamma-ray source located near the Galactic plane. At energies above 1 MeV, an excess consistent with the position of 2CG 135+01 is detected in the sum of the observations, at flux levels which are a factor of 10-100 below those published in the past. The detection significance of this excess, when the possible presence of underlying Galactic diffuse emission is neglected, is 6.6 sigma for 3 degrees of freedom. The differential photon spectrum in the 1-30 MeV energy range can be described by a power law with a spectral index of $1.95^{+0.2}_{-0.3}$. Due to the uncertainties involved in modelling the Galactic-disk diffuse emission underneath the source, the absolute flux levels must be considered uncertain by a factor of two. They are consistent with the extrapolation of the time-averaged spectrum of 2CG 135+01 measured with EGRET, thereby strengthening the identification. No significant temporal correlation between the gamma-ray emission and the monitored radio emission of the possible counterpart radio source GT 0236+610 (showing a 26.5 day modulation) is found.
  • Authors

  • vanDijk, R
  • Bennett, K
  • Bloemen, H
  • Collmar, W
  • Connors, A
  • Diehl, R
  • Hermsen, W
  • Lichti, GG
  • McConnell, Mark
  • Much, R
  • Schonfelder, V
  • Steinle, H
  • Stong, A
  • Tavani, M
  • Status

    Publication Date

  • November 1996
  • Has Subject Area

    Published In


  • gamma rays, observations
  • stars, individual, 2CG 135+01
  • stars, individual, GT 0236+610
  • Start Page

  • 485
  • End Page

  • 492
  • Volume

  • 315
  • Issue

  • 3