Observability of spherical photon orbits in near-extremal Kerr black holes
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DOI: 10.1103/physrevd.100.044058
Abstract: We investigate the spherical photon orbits in near-extremal Kerr spacetimes. We show that the spherical photon orbits with impact parameters in a finite range converge on the event horizon. Furthermore, we demonstrate that the Weyl… read more here.
Keywords: photon orbits; spherical photon; near extremal; orbits near ... See more keywords
Existence or absence of superregular boson clouds around extremal Kerr black holes and its connection with number theory
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DOI: 10.1103/physrevd.101.044040
Abstract: We argue about the (non) existence of {\it superregular} scalar clouds (i.e., bound states of a massive and complex-valued scalar field $\Psi$) around exact {\it extremal} ($a = M$) Kerr black holes (BH's) possessing {\it… read more here.
Keywords: number; superregular clouds; harmonics; existence ... See more keywords
Extremal Kerr white holes as a source of ultrahigh energy particles
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DOI: 10.1103/physrevd.102.024002
Abstract: We consider a process where two identical massive particles fall inwards, starting from rest at infinity towards the extremal Kerr black hole, collide outside the event horizon in its vicinity, and produce two massless particles.… read more here.
Keywords: energy particles; event horizon; energy; horizon ... See more keywords
Photon emissions from near-horizon extremal and near-extremal Kerr equatorial emitters
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DOI: 10.1103/physrevd.104.124005
Abstract: We consider isotropic and monochromatic photon emissions from equatorial emitters moving along future-directed timelike geodesics in the near-horizon extremal Kerr (NHEK) and near-horizon near-extremal Kerr (near-NHEK) regions, to asymptotic infinity. We obtain numerical results for… read more here.
Keywords: near horizon; equatorial emitters; horizon extremal; photon emissions ... See more keywords
Separating metric perturbations in near-horizon extremal Kerr spacetimes
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DOI: 10.1103/physrevd.96.064017
Abstract: Linear perturbation theory is a powerful toolkit for studying black hole spacetimes. However, the perturbation equations are hard to solve unless we can use separation of variables. In the Kerr spacetime, metric perturbations do not… read more here.
Keywords: metric perturbations; near horizon; separating metric; extremal kerr ... See more keywords