A theoretical unifying scheme for gamma-ray bright blazars

The phenomenology of gamma-ray bright blazars can be accounted for by a seq uence in the source power and intensity of the diffuse radiation field surr ounding the relativistic jet. Correspondingly, the equilibrium particle dis tribution peaks at different energies. This leads to a trend in the observe d properties. an increase of the observed power corresponds to: (i) a decre ase in the frequencies of the synchrotron and inverse Compton peaks, and (i i) an increase in the ratio of the powers of the high- and low-energy spect ral components. Objects along this sequence would be observationally classi fied respectively as high-frequency BL Lac objects, low-frequency BL Lac ob jects, high-polarization quasars and low-polarization quasars. The proposed scheme is based on the correlations among the physical paramet ers derived in the present paper by applying to 51 gamma-ray loud blazars t wo of the most accepted scenarios for the broad-band emission of blazars, n amely the synchrotron self-Compton and external Compton models. This also e xplains the observational trends presented by Fossati et al., dealing with the spectral energy distributions of all blazars. This gives us confidence that our scheme applies to all blazars as a class.