A comparative study of the absorption cross section of static regular black holes for electromagnetic field

In this article, we report our study on the absorption cross section for the electromagnetic field due to static spherically symmetric regular black holes of two distinct categories: the Fan-Wang generic class and the Simpson-Visser class. Existing studies on these two categories have relied on the WKB method, which applies to the low-frequency regime. In our analysis, we have numerically evaluated the absorption cross section for the electromagnetic field across all frequency ranges. To compute the absorption cross section, we followed a gauge-invariant approach, which avoids the need for gauge fixing for the electromagnetic field, thereby simplifying the methodology further. To emphasize the usefulness of this gauge invariant approach we have performed the same analysis for Simpson-Visser class black holes, which is more general in terms of the structure of the metric. For both types of regular black holes, the influence of regularization parameters on the absorption cross section reveals fundamental properties of their spacetime and their interactions with the surrounding astrophysical environment. Moreover, certain similarities observed between the Reissner-Nordström black hole and regular black holes of the Fan-Wang generic class indicate potential scenarios of correspondence between linear and nonlinear electrodynamics when coupled with gravity.