The unidentified TeV source (TeV J2032+4130) and surrounding field: Final HEGRA IACT-System results

¹ Max-Planck-Institut für Kernphysik, Postfach 103980, 69029 Heidelberg, Germany e-mail: [Gavin.Rowell;Dieter.Horns]@mpi-hd.mpg.de
² Yerevan Physics Institute, Alikhanian Br. 2, 375036 Yerevan, Armenia
³ Universität Hamburg, Institut für Experimentalphysik, Luruper Chaussee 149, 22761 Hamburg, Germany
⁴ Universität Kiel, Inst. f. Experimentelle und Angewandte Physik, Leibnizstr. 15-19, 24118 Kiel, Germany
⁵ Universität Wuppertal, Fachbereich Physik, Gaußstr. 20, 42097 Wuppertal, Germany
⁶ Max-Planck-Institut für Physik, Föhringer Ring 6, 80805 München, Germany
⁷ Universidad Complutense, Facultad de Ciencias Físicas, Ciudad Universitaria, 28040 Madrid, Spain
⁸ Now at Max-Planck-Institut für Physik, Föhringer Ring 6, 80805 München, Germany
⁹ Now at Washington University, St. Louis MO 63130, USA
¹⁰ Now at Humboldt Universität f. Physik, Unter den Linden 6, 10099 Berlin, Germany
¹¹ Altai State University, Dimitrov Street 66, 656099 Barnaul, Russia
¹² Now at Landessternwarte Heidelberg, Königstuhl, 69117 Heidelberg, Germany
¹³ Home institute: University Lodz, Poland
¹⁴ Now at Laboratoire Leprince-Ringuet, École Polytechnique, 91128 Palaiseau, France (IN2P3/CNRS)

Received: 29 June 2004
Accepted: 17 September 2004

Abstract

The unidentified TeV source in Cygnus is now confirmed by follow-up observations from 2002 with the HEGRA stereoscopic system of Cherenkov Telescopes. Using all data (1999 to 2002) we confirm this new source as steady in flux over the four years of data taking, extended with radius 6.2′ (± ± ) and exhibiting a hard spectrum with photon index -1.9. It is located in the direction of the dense OB stellar association, Cygnus OB2. Its integral flux above energies  TeV amounts to ~5% of the Crab assuming a Gaussian profile for the intrinsic source morphology. There is no obvious counterpart at radio, optical nor X-ray energies, leaving TeV J2032+4130 presently unidentified. Observational parameters of this source are updated here and some astrophysical discussion is provided. Also included are upper limits for a number of other interesting sources in the FoV, including the famous microquasar Cygnus X-3.