  We investigate shell emission associated with dying radio loud AGNs. First,
based on our recent work by Ito et al. (2015), we describe the dynamical and
spectral evolutions of shells after stopping the jet energy injection. We find
that the shell emission overwhelms that of the radio lobes soon after stopping
the jet energy injection because fresh electrons are continuously supplied into
the shell via the forward shock while the radio lobes rapidly fade out without
jet energy injection. We find that such fossil shells can be a new class of
target sources for SKA telescope. Next, we apply the model to the nearby radio
source 3C84. Then, we find that the fossil shell emission in 3C84 is less
luminous in radio band while it is bright in TeV gamma-ray band and it can be
detectable by CTA.
