No quantum gravity signature from the farthest quasars (F. Tamburini et al.)

Vol. 533
In section 2. Astrophysical processes

No quantum gravity signature from the farthest quasars

by F. Tamburini, C. Cuofano, M. Della Valle, and R. Gilmozzi, A&A 533, A71

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Quantum gravity is a central topic of field theory and cosmology, particularly in the context of dark energy. We examine the possibility that light propagating through a vacuum, is scattered by a foam of fluctuations causing the systematic degradation of the images of progressively more distant objects. We analyse archival Hubble Space Telescope ACS/HRC images of 25 milliarcsec resolution, using our newly developed approach. We compare quasi-stellar object (QSO) images in the redshift range from 4 to 6.3 with stellar images in the same field to determine the blurring (or phase dispersion) of the diffraction-limited images. The measured blurring upper limit rules out two classes of space-time foam and is consistent with isotropy on large scales.