The Broad Band Energy Distributions of a Complete Sample of Radio-selected BL Lacertae Objects
Session 88 -- Mulit-Wavelength Observations of Blazars and BL Lacertae Obj Objects
Oral presentation, Wednesday, 11, 1995, 10:00am - 11:30am

## [88.01D] The Broad Band Energy Distributions of a Complete Sample of Radio-selected BL Lacertae Objects

R. M. Sambruna, C. M. Urry (STScI), L. Maraschi (Univ. of Milan), G. Ghisellini (Univ. of Turin)

The complete 1 Jy sample of radio-selected BL Lacs (RBLs) of Stickel et al. (1991, ApJ 374, 431) was observed with the Rosat PSPC instrument (Urry et al., in prep.). Here we discuss the derived X-ray spectra in relation to the Broad-Band Energy Distributions (BBEDs). There is a wide spread in the shape of the multifrequency continuum emission of RBLs (which is well characterized by the radio-to-optical spectral index $\alpha_{ro}$), and in the way the X-ray spectra connect to lower frequencies. For low values of $\alpha_{ro}$ the BBEDs are similar to those of X-ray--selected BL Lacs, while for high $\alpha_{ro}$ the BBEDs resemble those of Flat Spectrum Radio Quasars. The correlations of spectral parameters characterizing the BBEDs with other relevant quantities are examined. The BBEDs of single representative objects and of subgroups are discussed in the frame of the current Blazar models, in order to find the more crucial physical quantity leading the smooth spectral change in spectral properties. It is argued that RBLs have properties intermediate between X-ray-selected BL Lacs on one hand and Flat Spectrum Radio Quasars and on the other.