OSSE Observations of the Bright Seyfert 1 Galaxy IC 4329A
Abstract
We present the first hard X-ray/soft γ-ray observations from the Oriented Scintillation Spectrometer Experiment (OSSE) of a bright Seyfert 1 galaxy, IC 4329A. Significant variability was seen over the 3 week observing period. The 50-200 keV spectrum is steep and can be characterized by a power-law spectrum of photon index 2.84 +/- 0.36, at 90% confidence. This is significantly steeper than the X-ray spectrum found from Ginga data of the source. Joint fits of the Ginga and OSSE data are well modeled by a thermal model represented by an exponential spectral break with an e-folding energy at about 130 keV. Good fits are also obtained if a reflection component is included. We constrain possible nonthermal continuum models involving photon-photon pair production. There is a similarity between the X-ray/γ-ray spectra of IC 4329A and Cygnus X-1.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- October 1993
- DOI:
- 10.1086/187070
- Bibcode:
- 1993ApJ...416L..57F
- Keywords:
-
- GALAXIES: INDIVIDUAL ALPHANUMERIC: IC 4329A;
- GALAXIES: SEYFERT;
- GAMMA RAYS: OBSERVATIONS;
- GAMMA RAYS: THEORY