The blazar sequence: a new perspective

Abstract

We revisit the so called "blazar sequence", which connects the observed bolometric luminosity to the shape of the spectral energy distribution (SED) of blazars. We propose that the power of the jet and the SED of its emission are linked to the two main parameters of the accretion process, namely the mass of the black hole and the accretion rate. We assume: i) that the jet kinetic power is proportional to the mass accretion rate; ii) that most of the jet dissipation takes place at a distance proportional to the black hole mass; iii) that the broad line region exists only above a critical value of the disk luminosity, in Eddington units, and iv) that the radius of the broad line region scales as the square root of the ionising disk luminosity. These assumptions, motivated by existing observations or by reasonable theoretical considerations, are sufficient to uniquely determine the SED of all blazars. This framework accounts for the existence of "blue quasars", i.e. objects with broad emission lines but with SEDs resembling those of low luminosity high energy peaked BL Lac objects, as well as the existence of relatively low luminosity "red" quasars. Implications on the possible evolution of blazars are briefly discussed. This scenario can be tested quite easily once the AGILE and especially the GLAST satellite observations, coupled with information in the optical/X-ray band from Swift, will allow the knowledge of the entire SED of hundreds (and possibly thousands) blazars.

Revised version, accepted for publication in MNRAS

References in corpus (10)

• The power of blazar jets
• Implications of very rapid TeV variability in blazars
• Rapid variability in TeV blazars: the case of PKS 2155-304
• The spectrum of the Broad Line Region and the high-energy emission of powerful blazars
• The Blazar Sequence: Validity and Predictions
• A sample of low-redshift BL Lacertae objects. II. EVN and MERLIN data and multi-wavelength analysis
• Synoptic studies of seventeen blazars detected in very high-energy gamma-rays
• Low energy cut-offs and hard X-ray spectra in high-z radio-loud quasars: the Suzaku view of RBS315
• IGR J22517+2218=MG3 J225155+2217: a new gamma-ray lighthouse in the distant Universe
• ROXA J081009.9+384757.0: a $10^{47}$ erg/s blazar with hard X-ray synchrotron peak or a new type of radio loud AGN?

Cited by in corpus (4)

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• Blazar nuclei in radio-loud narrow-line Seyfert 1?
• Patterns of variability in gamma-ray blazars
• SDSS spectroscopy for blazars in the $Fermi$ LAT bright AGN sample