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

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.