A theoretical unifying scheme for gamma-ray bright blazars

Abstract

The phenomenology of gamma-ray bright blazars can be accounted for by a sequence in the source power and intensity of the diffuse radiation field surrounding the relativistic jet. Correspondingly, the equilibrium particle distribution peaks at different energies. This leads to a trend in the observed properties: an increase of the observed power corresponds to: 1) a decrease in the frequencies of the synchrotron and inverse Compton peaks; 2) an increase in the ratio of the powers of the high and low energy spectral components. Objects along this sequence would be observationally classified respectively as high frequency BL Lac objects, low frequency BL Lac objects, highly polarized quasars and lowly polarized quasars. The proposed scheme is based on the correlations among the physical parameters derived in the present paper by applying to 51 gamma ray loud blazars two of the most accepted scenarios for the broad band emission of blazars, namely the synchrotron self--Compton and external Compton models, and explains the observational trends presented by Fossati et al. (1998) in a companion paper, dealing with the spectral energy distributions of all blazars. This gives us confidence that our scheme applies to all blazars as a class.Comment: 25 pages, 11 figures, uses mn.sty and psfig.tex. Accepted for publication in MNRA

NEW HIGH-z FERMI BL LACS WITH THE PHOTOMETRIC DROPOUT TECHNIQUE

“…In other words, theblazar sequence predicts the non-existence of high-frequency peaked, highly luminous BL Lac objects. A theoretical justification of these correlations is discussed in Ghisellini et al (1998). The concept of a Blazar sequence is an interesting but still debated idea (e.g., Ghisellini et al 2012;Padovani et al 2012).…”

From the ‘blazar sequence' to unification of blazars and radio galaxies

“…Fossati et al (1998) presented the blazar sequence: the peak luminosity of the synchrotron component (L peak ) and the Compton dominance (the ratio of the peak of the Compton to the synchrotron peak luminosity) are anti-correlation with the synchrotron peak frequency ν peak . Ghisellini et al (1998) modeled the broadband spectra of blazars, and suggested that along the blazar sequence (BL Lacs → FSRQs), a stronger radiative cooling causes a particle energy distribution with a break at lower energies. So the synchrotron ⋆ E-mail: ynzx@yeah.net and Compton peaks shift to lower frequencies.…”

Patterns of variability in γ-ray blazars

“…The latter population of photons can be the same synchrotron radiation (Synchrotron Self-Compton, SSC) or a source external to the jet, like the accretion disk or the broad-line region (External Compton, EC). and Ghisellini et al (1998) suggested that blazars follow a trend -the blazar sequence -where sources with low bolometric luminosity have both peaks at high frequencies (soft X-rays for synchrotron and TeV for IC), while, as the luminosity increases, both peaks shift to lower frequencies (optical/infrared for synchrotron and MeV/GeV for IC). See, however, Padovani (2007) and references therein for a discussion.…”