Volume 411, Number 1, November III 2003
Special letters issue on: first science with integral
|Page(s)||L405 - L410|
|Published online||17 November 2003|
Letter to the Editor
First INTEGRAL observations of Cygnus X-3*
Science Data Center, Chemin d'Écogia 16, 1290 Versoix, Switzerland
2 Observatory, PO Box 14, 00014 University of Helsinki, Finland
3 Centrum Astronomiczne im. M. Kopernika, Bartycka 18, 00-716 Warszawa, Poland
4 CNR-IASF, Sezione di Milano, via Bassini 15, 20133 Milano, Italy
5 Smithsonian Astrophysical Observatory, 60 Garden Street, MS 67, Cambridge, MA 02138-1516, USA
6 Institut für Astronomie and Astrophysik, Universität Tübingen, Sand 1, 72076 Tübingen, Germany
7 Geneva Observatory, Ch. des Maillettes 51, 1290 Sauverny, Switzerland
8 Laboratory for High Energy Astrophysics, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
9 Centre d'Études de Saclay, DAPNIA/Service d'Astrophysique, Orme des Merisiers, 91191 Gif-sur-Yvette Cedex, France
10 Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstrasse, 85748 Garching, Germany
11 Danish Space Research Institute, Juliane Maries Vej 30, 2100 Copenhagen Ø, Denmark
Corresponding author: O. Vilhu, firstname.lastname@example.org
Accepted: 18 August 2003
We present the first INTEGRAL results on Cyg X-3 from the PV phase observations of the Cygnus region. The source was clearly detected by the JEM-X, ISGRI and SPI. The INTEGRAL observations were supported by simultaneous pointed RXTE observations. Their lightcurves folded over the 4.8 hour binary period are compatible with the mean RXTE/ASM and CGRO/BATSE light curves. We fit our broad-band X-ray/γ-ray spectra with a physical model, which represents the first such published model for Cyg X-3. The main physical processes in the source are thermal Comptonization and Compton reflection with parameters similar to those found for black-hole binaries at high Eddington rates.
Key words: gamma rays: observations / radiation mechanisms: non-thermal / stars: individual: Cyg X-3 / X-rays: binaries / X-rays: general / X-rays: stars
© ESO, 2003
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