The hidden X-ray Seyfert nucleus in 3C 273: BeppoSAX results

Abstract

We present the results of BeppoSAX AO1 Core Program observations of 3C~273 performed in Jan. 1997 and compare them in detail with data obtained during the satellite Science Verification Phase (SVP), in Jul. 1996. Though a power law is an acceptable representation of the data in the whole 0.1-200 keV range, there is indication of a steepening of the spectrum as the energy increases. Our data mark a difference with respect to the SVP data, where a steeper power law below 0.5 keV, an absorption feature at 0.6 keV, and a more prominent fluorescence iron line have been found. The weakening of cold/warm matter signatures in our data with respect to the SVP ones may indicate that, at higher luminosities, the featureless continuum produced in a relativistic jet overwhelms any thermal and/or reprocessed radiation, while the two components were almost comparable during the lower state of Jul. 1996. We conclude that this radio--loud source shows evidence not only for thermal disk--like emission, but also substantial reprocessing of X-rays onto cold matter.