  The gamma-ray emission in broad-line blazars is generally explained as
inverse Compton (IC) radiation of relativistic electrons in the jet scattering
optical-UV photons from the Broad Line Region (BLR), the so-called BLR External
Compton scenario. We test this scenario on the Fermi gamma-ray spectra of 106
broad-line blazars detected with the highest significance or largest BLR, by
looking for cut-off signatures at high energies compatible with gamma-gamma
interactions with BLR photons. We do not find evidence for the expected BLR
absorption. For 2/3 of the sources, we can exclude any significant absorption
($\tau_{max}<1$), while for the remaining 1/3 the possible absorption is
constrained to be 1.5-2 orders of magnitude lower than expected. This result
holds also dividing the spectra in high and low-flux states, and for powerful
blazars with large BLR. Only 1 object out of 10 seems compatible with
substantial attenuation ($\tau_{max}>5$). We conclude that for 9 out of 10
objects, the jet does not interact with BLR photons. Gamma-rays seem either
produced outside the BLR most of the time, or the BLR is ~100x larger than
given by reverberation mapping. This means that i) External Compton on BLR
photons is disfavoured as the main gamma-ray mechanism, vs IC on IR photons
from the torus or synchrotron self-Compton; ii) the Fermi gamma-ray spectrum is
mostly intrinsic, determined by the interaction of the particle distribution
with the seed-photons spectrum; iii) without suppression by the BLR, broad-line
blazars can become copious emitters above 100 GeV, as demonstrated by 3C454.3.
We expect the CTA sky to be much richer of broad-line blazars than previously
thought.
