Understand
Recent observations with JWST have identified several bright galaxy candidates at $z\gtrsim 10$, some of which appear unusually massive (up to $\sim 10^{11}\ \rm M_{\odot}$).
- Such early formation of massive galaxies is difficult to reconcile with standard $\Lambda\rm CDM$ predictions, demanding very high star formation efficiency (SFE), possibly even in excess of the cosmic baryon mass budget in collapsed structures.
- With an idealized analysis based on linear perturbation theory and the Press-Schechter formalism, we show that the observed massive galaxy candidates can be explained with lower SFE than required in $\Lambda\rm CDM$, if structure formation is accelerated/seeded by massive ($\gtrsim 10^{9}\ \rm M_{\odot}$) primordial black holes (PBHs) that make a up a small fraction ($\sim 10^{-6}-10^{-3}$) of dark matter, considering existing empirical constraints on PBH parameters.
- We also discuss the potential observational signatures of PBH cosmologies in the JWST era.