TeV gamma-ray observations of SS-433 and a survey of the surrounding field with the HEGRA IACT-System

¹ Max-Planck-Institut für Kernphysik, Postfach 103980, 69029 Heidelberg, Germany, e-mail: Gavin.Rowell@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, Newtonstr. 15, Berlin, Germany
¹¹ Altai State University, Dimitrov Street 66, 656099 Barnaul, Russia;
¹² Now at Landessternwarte Heidelberg, Königstuhl, Heidelberg, Germany;
¹³ Home institute: University Lodz, Poland;
¹⁴ Now at Laboratoire Leprince-Ringuet, École Polytechnique, Palaiseau, France (IN2P3/CNRS);

Received: 25 October 2004
Accepted: 28 March 2005

Abstract

We present results of a search for TeV γ-ray emission from the microquasar SS-433 and the surrounding region covering a ~  field of view. Analysis of data taken with the HEGRA stereoscopic system of imaging atmospheric Čerenkov imaging telescopes reveals no evidence of steady or variable emission from any position. Observation times of over 100 h have been achieved in central parts of the field of view. We set 99% confidence level upper limits to a number of a-priori-chosen objects of interest, including SS-443 and its interaction regions, 32 pulsars, 3 supernova remnants and the GeV source GeV J1907+0537. Our upper limit of 3.2% Crab flux (for energies  TeV) for the eastern-lobe region e3 of SS-433 permits, after comparison with X-ray fluxes, a lower limit of G on the post-shocked magnetic field in this region. An ensemble upper limit at 0.3% Crab flux ( TeV) from a subset (11) of the 32 pulsars implies a maximum of 4.5% of the spin-down pulsar power is available for TeV γ-ray production. For one of the SNR in our FoV, 3C 396, recent Chandra observations suggest that a central pulsar-driven wind nebula may be the source of X-ray emission. Our upper limit implies that a maximum of 0.1% of the spin-down power from the central source of 3C 396 would be available for TeV γ-rays.