The BL lacertae objects OQ 530 and S5 0716+714 simultaneous observations in the X-rays, radio, optical and TeV bands

INAF – Osservatorio Astronomico di Brera, Via Brera 28, I-20121 Milano, ItalyReceived October 2002Abstract. We present the results of the BeppoSAX observations of two BL Lacs, OQ530 and S50716+714, as part of a ToOprogram for the simultaneous observation at radio, optical, X–ray and TeV energies. Both sources are detected in the LECS andMECS, with S50716+714 visible also in the PDS band, up to about ∼60 keV. The X-ray spectra of both sources are better fittedby a double power–law model, with a steep soft X–ray componen t flattening at harder energies, with breaks at 0.3 and 1.5 keV,respectively. The concave shape of the spectra in both objects is consistent with soft X–rays being produced by the synchrotronand harder X–rays by the inverse Compton processes. Also the X–ray variability properties confirm this scenario, in part icularfor S50716+714 our observation shows variations by about a factor 3 over one hour below ∼ 3 keV and no variability above.Their simultaneous broad band energy spectral distributions can be successfully interpreted within the frame of a homogeneoussynchrotron and inverse Compton model, including a possible contribution from an external source of seed photons with thedifferent spectral states of S50716+714 being reproduced by changing the injected power. The resulting parameters are fullyconsistent with the two sources being intermediate objects within the “sequence” scenario proposed for blazars.Key words. BL Lacetae objects: general – X-rays: galaxies – BL Lacetae objects: individual: OQ530, S50716+714