  Planets form in discs of gas and dust around stars, and continue to grow by
accretion of disc material while available. Massive planets clear a gap in
their protoplanetary disc, but can still accrete gas through a circumplanetary
disk. For high enough accretion rates the planet should be detectable at
infrared wavelengths. As the energy of the gas accreted on to the planet is
released, the planet surroundings heat up in a feedback process. We aim to test
how this planet feedback affects the gas in the coorbital region and the
accretion rate itself. We modified the 2D code FARGO-AD to include a
prescription for the accretion and feedback luminosity of the planet and use it
to model giant planets on 10 au circular and eccentric orbits around a solar
mass star. We find that this feedback reduces but does not halt the accretion
on to the planet, although this result might depend on the near-coincident
radial ranges where both recipes are implemented. Our simulations also show
that the planet heating gives the accretion rate a stochastic variability with
an amplitude $\Delta \dot{M}_p \sim 0.1 \dot{M}_p$. A planet on an eccentric
orbit ($e=0.1)$ presents a similar variability amplitude, but concentrated on a
well-defined periodicity of half the orbital period and weaker broadband noise,
potentially allowing observations to discriminate between both cases. Finally,
we find that the heating of the coorbital region by the planet feedback alters
the gas dynamics, reducing the difference between its orbital velocity and the
Keplerian motion at the edge of the gap, which can have important consequences
for the formation of dust rings.
