2001ApJ...549L..67L

The idea that the TeV air showers, thought to be produced by gamma rays greater than 10 TeV from Markarian 501, can be mimicked by coherent bunches of sub-TeV photons is reexamined, focusing on fundamental considerations. In particular, it is shown that the minimum spot size of a beam of photons arriving at Earth is on the order of a few kilometers unless a lens with certain characteristics is placed between the TeV laser and Earth. The viability of the production mechanism of coherent bunches of TeV photons proposed by M. Harwit et al. is also reassessed.