Axion cloud evaporation during inspiral of black hole binaries -- the effects of backreaction and radiation

Understand

Ultralight scalar fields such as axions can form clouds around rotating black holes (BHs) by the superradiant instability.

• It is important to consider the evolution of clouds associated with BH binaries for the detectability of the presence of clouds through gravitational wave signals and observations of the mass and spin parameters of BHs.
• We re-examine the impact on the axion cloud due to the tidal perturbation from the companion in a binary system taking into account the following points.
• First, we study the influence of higher-multipole moments.