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

R. van Dijk; K. Bennett; H. Bloemen; W. Collmar; A. Connors; R. Diehl; W. Hermsen; G. G. Lichti; M. McConnell; R. Much; V. Schoenfelder; H. Steinle; A. Strong; M. Tavani

arXiv · astro-ph/9604136

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

R. van Dijk·K. Bennett·H. Bloemen·W. Collmar·A. Connors·R. Diehl·W. Hermsen·G. G. Lichti·M. McConnell·R. Much·V. Schoenfelder·H. Steinle·A. Strong·M. Tavani

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Abstract

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.

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R. van Dijk, K. Bennett, H. Bloemen, W. Collmar, A. Connors, R. Diehl, W. Hermsen, G. G. Lichti, M. McConnell, R. Much, V. Schoenfelder, H. Steinle, A. Strong, M. Tavani. 1996-04-23. COMPTEL detection of the high-energy gamma-ray source 2CG 135+01. https://arxiv.org/abs/astro-ph/9604136

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