Cosmological black holes are not described by the Thakurta metric: LIGO-Virgo bounds on PBHs remain unchanged

Understand

We show that the physical conditions which induce the Thakurta metric, recently studied by B{\oe}hm {\it et al.} in the context of time-dependent black hole masses, correspond to a single accreting black hole in the entire Universe filled with isotropic non-interacting dust.

• In such a case, the physics of black hole accretion is not local but tied to the properties of the whole Universe.
• We show that radiation, primordial black holes or particle dark matter cannot produce the specific energy flux required for supporting the mass growth of Thakurta black holes.
• In particular, this solution does not apply to black hole binaries.