Data di Pubblicazione:
2012
Abstract:
Blazars constitute the most enigmatic class of extragalactic γ -ray sources, and their observational features have
been ascribed to a relativistic jet closely aligned to the line of sight. They are generally divided in two main
classes: the BL Lac objects (BL Lacs) and the flat-spectrum radio quasars (FSRQs). In the case of BL Lacs the
double-bumped spectral energy distribution (SED) is generally described by the synchrotron self-Compton (SSC)
emission, while for the FSRQs it is interpreted as due to external Compton (EC) emission. Recently, we showed
that in the [3.4]–[4.6]–[12]μm color–color diagram the blazar population covers a distinct region (i.e., the WISE
blazar Strip (WBS)) clearly separated from the other extragalactic sources that are dominated by thermal emission.
In this paper, we investigate the relation between the infrared and γ -ray emission for a subset of confirmed blazars
from the literature, associated with Fermi sources, for which WISE archival observations are available. This sample
is a proper subset of the sample of sources used previously, and the availability of Fermi data is critical to constrain
the models on the emission mechanisms for the blazars. We found that the selected blazars also lie on the WBS
covering a narrower region of the infrared color–color planes than the overall blazar population. We then found an
evident correlation between the IR and γ -ray spectral indices expected in the SSC and EC frameworks. Finally,
we determined the ratio between their γ -ray and infrared fluxes, a surrogate of the ratio of powers between the
inverse Compton and the synchrotron SED components, and used such parameter to test different blazar emitting
scenarios.
Tipologia CRIS:
03A-Articolo su Rivista
Keywords:
BL Lacertae objects: general , gamma rays: galaxies , infrared: galaxies , radiation mechanisms: non-thermal
Elenco autori:
R. D'Abrusco;F. Massaro;M. Ajello;J. E. Grindlay;Howard A. Smith;G. Tosti
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