  It is argued that, in heavy ion collisions, thermal dileptons are good probes
of the transport properties of the medium created in such events, and also of
its early-time dynamics, usually inaccessible to hadronic observables. In this
work we show that electromagnetic azimuthal momentum anisotropies do not only
display a sensitivity to the shear relaxation time and to the initial
shear-stress tensor profile, but also to the temperature dependence of the
shear viscosity coefficient.
