I believe that if in the vacuum of space you place a blackbody object with (a) a constant (i.e.,
unchanging energy per unit time) internal thermal energy source, and (b) internal / surface thermal conduction properties such that independent of how energy enters the blackbody, the surface temperature of the blackbody is everywhere the same and you place that object in cold space (no background thermal radiation of any kind), eventually the object will come to a steady
state condition — i.e., the object will eventually radiate energy to space at a
rate equal to the
rate of energy produced by the internal energy source.