# The Spectral Energy Distribution of Fermi bright blazars

Abstract : We have conducted a detailed investigation of the broad-band spectral properties of the \gamma-ray selected blazars of the Fermi LAT Bright AGN Sample (LBAS). By combining our accurately estimated Fermi gamma-ray spectra with Swift, radio, infra-red, optical and other hard X-ray/gamma-ray data, collected within three months of the LBAS data taking period, we were able to assemble high-quality and quasi-simultaneous Spectral Energy Distributions (SED) for 48 LBAS blazars.The SED of these gamma-ray sources is similar to that of blazars discovered at other wavelengths, clearly showing, in the usual Log $\nu$ - Log $\nu$ F$_\nu$ representation, the typical broad-band spectral signatures normally attributed to a combination of low-energy synchrotron radiation followed by inverse Compton emission of one or more components. We have used these SEDs to characterize the peak intensity of both the low and the high-energy components. The results have been used to derive empirical relationships that estimate the position of the two peaks from the broad-band colors (i.e. the radio to optical and optical to X-ray spectral slopes) and from the gamma-ray spectral index. Our data show that the synchrotron peak frequency $\nu_p^S$ is positioned between 10$^{12.5}$ and 10$^{14.5}$ Hz in broad-lined FSRQs and between $10^{13}$ and $10^{17}$ Hz in featureless BL Lacertae objects.We find that the gamma-ray spectral slope is strongly correlated with the synchrotron peak energy and with the X-ray spectral index, as expected at first order in synchrotron - inverse Compton scenarios. However, simple homogeneous, one-zone, Synchrotron Self Compton (SSC) models cannot explain most of our SEDs, especially in the case of FSRQs and low energy peaked (LBL) BL Lacs. (...)
Keywords :
Document type :
Journal articles
Domain :

http://hal.in2p3.fr/in2p3-00496030
Contributor : Virginie Mas <>
Submitted on : Tuesday, June 29, 2010 - 3:08:39 PM
Last modification on : Monday, April 5, 2021 - 2:26:07 PM

### Citation

A.A. Abdo, Markus Ackermann, Marco Ajello, Magnus Axelsson, Luca Baldini, et al.. The Spectral Energy Distribution of Fermi bright blazars. The Astrophysical Journal, American Astronomical Society, 2010, 716, pp.30-70. ⟨10.1088/0004-637X/716/1/30⟩. ⟨in2p3-00496030⟩

Record views