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COMPTEL MeV Observations of the TeV Sources Markarian 421 and Markarian 501

W. Collmar·K. Bennett·H. Bloemen·W. Hermsen·J. Ryan·V. Schoenfelder·H. Steinle·O. R. Williams
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Abstract

The COMPTEL experiment aboard the COMPTON Gamma-Ray Observatory (CGRO) has observed the prominent TeV-blazars Mkn 421 and Mkn 501 many times between the start of its mission in April '91 and December '98. This paper reports first COMPTEL results from mainly time-averaged (CGRO Cycles) data. No evidence for both sources is found up to the end Cycle VI. However, the sum of all 10-30 MeV Cycle VII data shows a weak (3.2 sigma detection) MeV-source being positionally consistent with Mkn 421. During Cycle VII Mkn 421 was rather active at TeV-energies. Due to the lack of other known Gamma-ray sources in this sky region, we consider Mkn 421 as the most likely counterpart for this Gamma-ray emission. However, its connection cannot be proven by COMPTEL.

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W. Collmar, K. Bennett, H. Bloemen, W. Hermsen, J. Ryan, V. Schoenfelder, H. Steinle, O. R. Williams. 1999-12-02. COMPTEL MeV Observations of the TeV Sources Markarian 421 and Markarian 501. https://arxiv.org/abs/astro-ph/9912042

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