Eric S. Perlman, Y. Jack Ng, David J. E. Floyd, Wayne A. Christiansen. Using Observations of Distant Quasars to Constrain Quantum Gravity
Natural Sciences / Astronomy / Cosmology
Submitted on: Aug 26, 2012, 06:23:42
Description: When calculating the path taken by photons as they travel from a distant source to Earth, one must use the comoving distance rather than the luminosity distance. This then also becomes the appropriate distance to use when calculating the angular broadening expected in a distant source. The use of the wrong distance measure causes Tamburini et al. to overstate the constraints that can be placed on models of spacetime foam. In addition, we consider the impact of different ways of parametrizing and measuring the effects of spacetime foam. Given the variation of the shape of the point-spread function (PSF) on the chip, as well as observation-specific factors, it is important to select carefully -- and document -- the comparison stars used as well as the methods used to compute the Strehl ratio.