The blazar sequence: a new perspective

By G. Ghisellini, F. Tavecchio. 2008

266 citations recorded by the source corpus.

We revisit the so called “blazar sequence”, which connects the observed bolometric luminosity to the shape of the spectral energy distribution (S ED) 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 r ate; 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 th e ionising disk luminosity. These assumptions, motivated by existing observations or by reasonable theoretical considerations, are sufficient to uniquely determine the SED of all blazars. T his framework accounts for the existence of “blue quasars”, i.e. objects with broad emissi on 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 o nce the AGILE and especially the GLAST satellite observations, coupled with information in the op tical/X‐ray band from Swift, will allow the knowledge of the entire SED of hundreds (and possibly thousands) blazars.

Subfields: Astronomy and Astrophysics, Instrumentation, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/9c8cb844af61342e3ae0c832cda8a4048eb1f8df

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Citations in the corpus

SPECTROSCOPY OF THE LARGEST EVER γ-RAY-SELECTED BL LAC SAMPLE (2013, background): “Such transition objects support the idea of a Blazar continuum, rather than two distinct populations (Fossati et al. 1998; Ghisellini & Tavecchio 2008).”
TeV BL Lac objects at the dawn of the Fermi era (2009, background): “Faster variations (such as those observed in PKS 2155−304 and Mkn 501: Aharonian et al. 2007a; Albert et al. 2007a) require modifications of this scheme (Ghisellini & Tavecchio 2008b; Ghisellini et al. 2009b; Giannios, Uzdensky & Begelman 2009; Neronov, Semikoz & Sibiryakov 2008).”
A Multimessenger Picture of the Flaring Blazar TXS 0506+056: Implications for High-energy Neutrino Emission and Cosmic-Ray Acceleration (2018, background): “26BLR cov» erg cm −3, where fcov is the covering fraction (Ghisellini & Tavecchio 2008).”
A simplified view of blazars: clearing the fog around long‐standing selection effects (2011, background): “…of intense discussions since its first proposal by Fossati et al. (1998) and Ghisellini et al. (1998) (e.g., Giommi, Menna & Padovani 1999; Padovani et al. 2003; Caccianiga & Marchã 2004; Nieppola et al. 2006; Padovani 2007; Ghisellini & Tavecchio 2008; Nieppola et al. 2008; Giommi et al. 2011).”
The Fermi blazar sequence (2017, methodology): “This is because we expect that the parameter controlling the sequence is not the mere luminosity, but the luminosity in units of Eddington, as proposed by Ghisellini & Tavecchio (2008).”
CONSTRAINING EMISSION MODELS OF LUMINOUS BLAZAR SOURCES (2009, methodology): “In the case of luminous blazars, the observed synchrotron peak frequencies seem to cluster within a relatively narrow frequency range 1012–1014 Hz (Ghisellini & Tavecchio 2008 and references therein).”
Simultaneous Planck, Swift, and Fermi observations of X-ray and γ-ray selected blazars (2011, background): “…between bolometric luminosity and νSpeakclaimed by Fossati et al. (1998) and Ghisellini et al. (1998) that remains a subject of lively debate (e.g., Giommi et al. 1999; Padovani et al. 2003; Caccianiga & Marchã 2004; Nieppola et al. 2006; Padovani 2007; Ghisellini & Tavecchio 2008).”
FROM THE BLAZAR SEQUENCE TO THE BLAZAR ENVELOPE: REVISITING THE RELATIVISTIC JET DICHOTOMY IN RADIO-LOUD ACTIVE GALACTIC NUCLEI (2011, background): “Optical Spectral Type and the Envelope While the original observational sequence of Fossati et al. (1998) implied a transition from quasars to line-less BL Lacs along a sequence from high to low bolometric luminosity, a firm distinction is not a necessary part of the theoretical scheme for a continu”
The Fermi blazars' divide (2009, background): “Indeed, for TeV BL Lacs, which span the entire region of BL Lacs, the available estimates indicate high black hole masses (e.g. Wagner 2008, Ghisellini & Tavecchio 2008a), in some cases exceeding109M⊙.”
FERMI/LARGE AREA TELESCOPE DISCOVERY OF GAMMA-RAY EMISSION FROM A RELATIVISTIC JET IN THE NARROW-LINE QUASAR PMN J0948+0022 (2009, background): “In fact challenges have been raised to the validity of the sequence (for a review, see Padovani 2007 and references therein), which however could be overcome (Maraschi et al. 2008, Ghisellini & Tavecchio 2008).”
Canonical high power blazars (2009, methodology): “The total power carried by the jet,Pj, was assumed in Ghisellini & Tavecchio (2008) to be related to the mass accretionrate, i.e.Pj = ηjṀc2.”
The transition between BL Lac objects and flat spectrum radio quasars (2010, methodology): “We interpret this behavior (see also G10 and Ghisellini & Tavecchio 2008) as follows.”