Isn't that where the 'therefore acts as dark energy' bit comes from? From the paper:PeterDonis said:The key requirement for the paper's claim is "dynamical mass", and that is the most questionable one. How does this "dynamical mass" work without violating the condition that the covariant divergence of the stress-energy tensor must be zero?
Later on, they cite Croker et al. 2020 for that (and both refer to Gliner 1966 as seminal). Perhaps criticism of whether the theory is correct should be aimed at those papers?I'd like to note for the discussion, that the specific claim the paper makes is not that BHs (or, what we tend to think of as black holes) >can< grow with expansion or act as DE - these are taken as given, to claim that BHs with these properties are consistent with the two kinds of observational data shown in the paper. I.e., they are saying something along the lines of 'maybe we should take these particular models more seriously because it kinda fits?'Section 3.1 said:When accretion becomes subdominant to growth by cosmological coupling, this population of BHs will contribute in aggregate as a nearly cosmologically constant energy density.
From conservation of stress-energy, this is only possible if the BHs also contribute cosmological pressure equal to the negative of their energy density, making k ∼ 3 BHs a cosmological dark energy species.
This is observational astronomy, not theory development. They work out very little in terms of new ideas in the paper. It 'merely' attempts to tie together earlier work into a new picture.