We consider rotating charged black holes with a scalar dilaton field and
surrounded by plasma, and we study their shadows. The metric is obtained from
the static solution by using the Newman-Janis algorithm. Assuming a suitable
form for the plasma distribution, we separate the Hamilton-Jacobi equation for
light and we derive an expression for the shape of the shadow. We present some
examples of contours and we study their observable properties as functions of
the charge and the dilaton coupling. We find that the presence of plasma
introduces a dependency on the frequency, with the shadow becoming smaller as
the frequency decreases.
