Rotating black holes in the Hernquist galactic halo and its accretion disk luminosity

Static, spherically symmetric black holes immersed in a dark matter halo with a Hernquist-type density profile have been derived by Cardoso et. al. in Ref. \redcite{Cardoso:2021wlq}. Using the Newman-Janis algorithm, we construct the metric for a stationary and axially symmetric rotating black hole in this environment. Then, we obtain the electromagnetic properties of thin accretion disks around such rotating black holes by utilizing the steady-state Novikov-Thorne model, and study the effects of spin parameter and halo compactness parameter on the disk properties. Finally, by comparison the results of the rotating Cardoso black hole with that of Kerr black hole in the absence of dark matter, we find that the presence of dark matter can not significantly affect the disk properties and thus for astrophysical black holes with large spin parameter, the distinction of rotating Cardoso black holes becomes more difficult than the Kerr black hole.