Circular motion and QPOs near BHs surrounded by dust fields in f(R, T) gravity

Exploring exotic matter around black holes (BHs) under different conditions, using equations of state and astrophysical observational data from BHs, may deepen our understanding of the nature of dark matter and theories of gravity. In the present work, we first briefly introduce a BH solution surrounded by a dust field in f ( R, T ) gravity and study the properties of the horizon around the BH. We investigate scalar invariants of the spacetime geometry, such as the Ricci scalar, the square of the Ricci tensor, and the Kretchman scalar. We also study the circular motion of test particles. Additionally, we investigate the effects of the dust field on the innermost stable circular orbits (ISCOs) and the particle’s energy and angular momentum at the ISCO. Moreover, we investigate particle oscillations near ISCO around the BH and calculate the frequencies of Keplerian orbits and vertical oscillations. As an astrophysical application of the studies, we study quasiperiodic oscillations (QPOs) in various QPO models. Finally, we obtain constraints on the dust field and BH parameters using a Monte Carlo Markov Chain (MCMC) simulation across the multidimensional parameter space for the microquasars GRO J1655-40 & GRS 1915-105, the Milky Way, and the M82 X-1 galaxy.