  We study heat radiation and radiative heat transfer for nanoparticles in the
presence of an infinitely long cylinder in different geometrical
configurations, based on its electromagnetic Green's tensor. The heat radiation
of a single particle can be enhanced by placing it close to a nanowire, and
this enhancement can be much larger as compared to placing it close to a plate
of the same material. The heat transfer along a cylinder decays much slower
than through empty vacuum, being especially long-ranged in the case of a
perfectly conducting nanowire, and showing nonmonotonic behavior in the case of
a SiC cylinder. Exploring the dependence on the relative azimuthal angle of the
nanoparticles, we find that the results are insensitive to small angles, but
they can be drastically different when the angle is large, depending on the
material. Finally, we demonstrate that a cylinder can either enhance or block
the heat flux when placed perpendicular to the interparticle distance line,
where the blocking in particular is strongly enhanced compared to the geometry
of a sphere of same radius.
