Paolo De Gregorio - INFN Padova #
On the effect of heat fluxes on the vibrational energy of a solid #
Starting from operational concerns in Gravitational Waves detection 
attempts, the RareNoise collaboration has devised a few experiments to 
determine whether nonequilibrium should be expected to play a role in a 
large class of precision measurements. The most impacting result has 
been to demonstrate that temperature differences across a macroscopic 
oscillator cause a marked increase of the amplitude of the fluctuations 
of a few low-frequency resonant modes. If one were to make use of the 
concept of effective temperature, it would mean that to within room 
temperature, the equivalent energy stored in those modes is of the order 
of 400 and up to 900 K. From another perspective, this may be viewed as 
an explicit measurable violation of the energy equipartition principle 
induced by a heat flux. Numerical simulation results of a semi-open 
linear chain are in agreement with the experimental finding, which can 
be explained at the most basic level also theoretically. One assumes 
that heat fluxes go hand in hand with an increase of intermodal correlations, which can 
sometimes become measurable depending on the strength of the coupling.