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Does circumventing the curvature singularity of the Kerr black hole affects
the timescale of the scalar cloud formation around it? By definition, the
scalar cloud, forms a gravitational atom with hydrogen-like bound states, lying
on the threshold of a massive scalar field’s superradiant instability regime
(time-growing quasi-bound states) and beyond (time-decaying quasi-bound
states). By taking a novel type of rotating hollow regular black hole proposed
by Simpson and Visser which unlike its standard rivals has an asymptotically
Minkowski core, we address this question. The metric has a minimal extension
relative to the standard Kerr, originating from a single regularization
parameter $\ell$, with length dimension. We show with the inclusion of the
regularization length scale $\ell$ into the Kerr spacetime, without affecting
the standard superradiant instability regime, the timescale of scalar cloud
formation gets shorter. Since the scalar cloud after its formation, via energy
dissipation, can play the role of a continuum source for gravitational waves,
such a reduction in the instability growth time improves the phenomenological
detection prospects of new physics because the shorter the time, the more
astrophysically important.

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