  Burrage, Davis, and Shaw recently suggested exploiting the correlations
between high and low energy luminosities of astrophysical objects to probe
possible mixing between photons and axion-like particles (ALP) in magnetic
field regions. They also presented evidence for the existence of ALP's by
analyzing the optical/UV and X-ray monochromatic luminosities of AGNs. We
extend their work by using the monochromatic luminosities of 320 unobscured
Active Galactic Nuclei from the Sloan Digital Sky Survey/Xmm-Newton Quasar
Survey (Young et al., 2009), which allows the exploration of 18 different
combinations of optical/UV and X-ray monochromatic luminosities. However, we do
not find compelling evidence for the existence of ALPs. Moreover, it appears
that the signal reported by Burrage et al. is more likely due to X-ray
absorption rather than to photon-ALP oscillation.
