We report the XMM-Newton discovery of the first Compton-thick obscured AGN in a Broad Line Radio Galaxy , the Gigahertz Peaked-Spectrum source Mkn 668 ( OQ+208 ) .
The remarkably flat 2–10 keV X-ray spectrum ( observed photon index , \Gamma \simeq 0.7 ) , alongside with a prominent iron K _ { \alpha } fluorescent emission line , is a clear signature of a Compton-reflection dominated spectrum .
Mkn 688 represents a remarkable example of discrepancy between X-ray spectral properties and optical classification , as its optical spectrum is characterized by broad and asymmetric Balmer lines .
The obscuring matter is constrained to be located within the radio hotspots , in turn separated by about 10 pc .
If the jets are piercing their way through a Compton-thick medium pervading the nuclear environment , one could be largely underestimating the radio activity dynamical age determined from the observed hotspot recession velocity .
The soft X-ray spectrum is dominated by a much steeper component , which may be due to nuclear continuum electron scattering , or inverse Compton of the - remarkably large - far infrared emission .
Soft X-rays are suppressed by a further Compton-thin ( N _ { H } \sim 10 ^ { 21 } cm ^ { -2 } ) absorbing system , that we identify with matter responsible for free-free absorption of the radio lobes .