  We investigate coarse-grained models of suspended self-thermophoretic
microswimmers. Upon heating, the Janus spheres, with hemispheres made of
different materials, induce a heterogeneous local solvent temperature that
causes the self-phoretic particle propulsion.
  Starting from atomistic molecular dynamics simulations, we verify the
coarse-grained description of the fluid in terms of a local molecular
temperature field, and its role for the particle's thermophoretic
self-propulsion and hot Brownian motion.
  The latter is governed by effective nonequilibrium temperatures, which are
measured from simulations by confining the particle position and orientation.
They are theoretically shown to remain relevant for any further spatial
coarse-graining towards a hydrodynamic description of the entire suspension as
a homogeneous complex fluid.
