The Blazar Sequence 2.0

Abstract

I discuss the spectral energy distribution (SED) of all blazars with redshift detected by the {\it Fermi} satellite and listed in the 3LAC catalog. I will update the so called "blazar sequence" from the phenomenological point of view, with no theory or modelling. I will show that: i) pure data show that jet and accretion power are related; ii) the updated blazar sequence maintains the properties of the old version, albeit with a less pronounced dominance of the $\gamma$--ray emission; iii) at low bolometric luminosities, two different type of objects have the same high energy power: low black hole mass flat spectrum radio quasars and high mass BL Lacs. Therefore, at low luminosities, there is a very large dispersion of SED shapes; iv) in low power BL Lacs, the contribution of the host galaxy is important. Remarkably, the luminosity distribution of the host galaxies of BL Lacs are spread in a very narrow range; v) a simple sum of two smoothly joining power laws can describe the blazar SEDs very well.