[nikhilgk]

So if I understood you and the original paper correctly, this observation is not in conflict with the Standard Model or Lambda-CDM and that this is an observational outcome of general relativity. Is that a correct statement? If so, then those models may need to incorporate why this may have happened, right?

Edit: Thank you for the detailed post. Learned a few things from it.

[raattgift]

It's support for \Lambda-CDM, which is the standard model of cosmology. The standard model of particle physics is only involved to the extent that it explains spectral emission and absorption lines in the first place; locally the physics of electromagnetism vs hydrogen ions (among others) works the same over-there-back-then and here-and-now.

Sorry that there's two "standard model"s. One often hears "concordance model" or "standard cosmology" or \Lambda-CDM instead, as a result.

This study's novelty is in showing that [a] the changing luminosities of both families of variable quasar can be usefully compared and [b] similar variable quasars have similar luminosity-changing rates at similar redshift; if the redshifts differ, the less-redshifted one's brightness changes more frequently and more quickly.