PT Journal
AU Maso-Ferrando, A
   Sanchis-Gual, N
   Font, JA
   Olmo, GJ
TI Birth of baby universes from gravitational collapse in a modified-gravity scenario
SO Journal of Cosmology and Astroparticle Physics
JI J. Cosmol. Astropart. Phys.
PY 2023
BP 028
EP 19pp
VL 06
IS 6
DI 10.1088/1475-7516/2023/06/028
LA English
DE modified gravity; Wormholes
AB We consider equilibrium models of spherical boson stars in Palatini f (R) = R + CR2 gravity and study their collapse when perturbed. The Einstein-Klein-Gordon system is solved using a recently established correspondence in an Einstein frame representation. We find that, in that frame, the endpoint is a nonrotating black hole surrounded by a quasi -stationary cloud of scalar field. However, the dynamics in the f (R) frame is dramatically different. The innermost region of the collapsing object exhibits the formation of a finite -size, exponentially-expanding baby universe connected with the outer (parent) universe via a minimal area surface (a throat or umbilical cord). Our simulations indicate that this surface is at all times hidden inside a horizon, causally disconnecting the baby universe from observers above the horizon. The implications of our findings in other areas of gravitational physics are also discussed.
ER