Probing the Physics of the Circumgalactic Medium using Fast Radio Bursts: Insights from CAMELS

The physics of the circumgalactic medium (CGM) is complex and not well understood. It is essential that we understand the processes and properties of baryons in the CGM as within are encoded formation history, feedback mechanisms of galaxy evolution, and a portion of the “missing” baryons. In the era of multi-wavelength astronomical surveys, one promising probe of the CGM are fast radio bursts (FRBs), millisecond-long luminous extragalactic pulses. The dispersion measure (DM) of FRBs is useful for quantifying and locating baryons in the CGM as it is solely a function of the electron density distribution. We analyze the CAMELS simulations, comprising over 6000 state-of-the-art cosmological simulations, and spanning a wide range of astrophysical and cosmological parameters. We explore how the implementation of CGM physics impacts the DM of FRBs. We investigate the distribution of DM resulting from varying cosmological (Ω_M, σ₈) and astrophysical parameters (stellar and AGN feedback), finding that Ω_M and the star formation rate result in significant differences in the distribution of DM. We explore the evolution of DM with redshift, comparing to previous models. We measure the excess DM associated with FRBs that interact with the CGM. Finally, we calculate the F parameter, an essential parameter that quantifies the effect of feedback, for each simulation run. We include a correction factor to F to account for the lack of representative cosmic variance due to the small box size.