New Limits to the IR Background: Bounds on Radiative Neutrino Decay and   on VMO Contributions to the Dark Matter Problem
  From considering the effect of gamma-gamma interactions on recently observed TeV gamma-ray spectra, improved limits are set to the density of extragalactic infrared (IR) photons which are robust and essentially model-independent. The resulting limits are up to two orders of magnitude more restrictive than direct observations in the 0.025-0.3eV regime. These limits are used to improve constraints on radiative neutrino decay in the mass range above 0.05eV and on Very Massive Objects (VMOs) as providing the dark matter needed to explain galaxy rotation curves. 
S.D. Biller, J. Buckley, A. Burdett, J. Bussons Gordo, D.A.   Carter-Lewis, D.J. Fegan, J. Findley, J.A. Gaidos, A.M. Hillas...