Context : The flat-spectrum radio quasar 4C + 71.07 is a high-redshift ( z = 2.172 ) , \gamma -loud blazar whose optical emission is dominated by the thermal radiation from accretion disc .

Aims:4C + 71.07 has been detected in outburst twice by the AGILE \gamma -ray satellite during the period end of October – mid November 2015 , when it reached a \gamma -ray flux of the order of F _ { E > 100 MeV } = ( 1.2 \pm 0.3 ) \times 10 ^ { -6 } photons cm ^ { -2 } s ^ { -1 } and F _ { E > 100 MeV } = ( 3.1 \pm 0.6 ) \times 10 ^ { -6 } photons cm ^ { -2 } s ^ { -1 } , respectively , allowing us to investigate the properties of the jet and of the emission region .

Methods : We investigated its spectral energy distribution by means of almost simultaneous observations covering the cm , mm , near-infrared , optical , ultra-violet , X-ray and \gamma -ray energy bands obtained by the GASP-WEBT Consortium , the Swift and the AGILE and Fermi satellites .

Results : The spectral energy distribution of the second \gamma -ray flare ( the one whose energy coverage is more dense ) can be modelled by means of a one-zone leptonic model , yielding a total jet power of about 4 \times 10 ^ { 47 } erg s ^ { -1 } .

Conclusions : During the most prominent \gamma -ray flaring period our model is consistent with a dissipation region within the broad-line region .
Moreover , this class of high-redshift , large-mass black-hole flat-spectrum radio quasars might be good targets for future \gamma -ray satellites such as e-ASTROGAM .