The Galactic Center black hole, Sgr A*, as a probe of new gravitational physics with the scalaron fifth force.
Abstract (from CDS):
The Galactic Center black hole (Sgr A*) provides an ideal laboratory for astronomical tests of new gravitational physics. This work reports that curvature correction (f(R)) to quantum vacuum fluctuations naturally yields a Yukawa-type scalar fifth force with potential exp(-Mψr)/r, where Mψ is the mass of the f(R) scalarons. Estimating the UV and IR cutoff scales of vacuum fluctuations, the Yukawa coupling strength is connected to the scalaron field amplitude. Whereas recently constrained Yukawa coupling and range correspond to light scalarons with Mψ = (1.37 x 10–21-5.49 x 10–20) eV, vacuum fluctuations yield a massive scalaron with Mψ = 10–16 eV. Scalaron-induced periastron shift of stellar orbits near Sgr A* has been studied with respect to the semimajor axis in the range a = 10-1000 au. It is found that the scalarons resulting from quantum fluctuations affect the precession of orbits with a = 128-256 Rs. The possibility of future constraints on massive scalarons in observations near Sgr A* is discussed. This is a new and independent effort to express a prototype quantum gravity effect in terms of astronomically accessible quantities.