High Energy Collision of Particles in the Vicinity of Extremal BHs in Higher Dims Masashi KIMURA (YITP, Kyoto university) w/ N.Tsukamoto and T.Harada New Perspectives on Cosmology, APCTP

High energy particle collision is also possible around higher-dim BHs. BSW process Collision of two particles with arbitrarily high center of mass energy can occur around rapidly rotating BH (in 4Dim) . High energy particle collision is also possible around higher-dim BHs.

Contents ・summary ・BSW process in 4D ・fine tuning and ISCO scenario ・”Instability” of extremal BH ・BSW process in higher Dims

Particle motion around Kerr BH 縄文式土器　　

are symmetric directions Motion of particle are symmetric directions (energy , angular momentum )

Maximally rotating case asymptote to BH horizon horizon

asymptotes to BH horizon “velocity”

not fine tuned Center of mass energy can be very large

center of mass energy

on horizon BSW (2009)

conditions for BSW process ・ extremal horizon ・ fine tuned parameters Fine tuning is naturally realized by an ISCO particle

ISCO (innermost stable circular orbit) ・ The inner edge of the standard accretion disk is given by the ISCO. ・ Compact object inspirals around a super-massive BH. Once the compact object reaches the radius of the ISCO, it begins to plunge into the BH. ISCO particle is naturally realized.

ISCO particles in fine tuned !!

collision of two particles Harada, Kimura (2011) ISCO particle not fine tuned

ISCO scenario and BSW process existence of ISCO scenario BSW process ?? ISCO circular orbit = centrifugal force gravitational force

Higher dimensional case ISCO does not exist in

Higher dimensional case BSW ISCO If is correct, BSW process does not work in higher dimensions However, another point of view suggests BSW process can work

Linear unstable? linear perturbation around Kerr BH Kimura+ (2011) linear perturbation around Kerr BH We can construct a perturbation which can be described by a linear perturbation around an extremal Kerr BH initially, but it cannot be after time evolution.

Linear instability of fields Aretakis (2011) on the horizon of extremal BH blows up in late times

Analogy between two instability ・ ： a particle or a field can stay in the vicinity of the horizon ・A wave with sufficiently short wavelength behaves like a test particle BSW field instability

Higher dimensional case Recently, it was shown that field instabilities appear in higher dimensional case (Murata,2012) BSW field instability BSW process also works suggest

BSW process in higher dims In , we showed that can be arbitrarily large around extremal Myers-Perry BH with equal angular momenta if (i) horizon is extremal (ii) parameter is fine tuned are satisfied.

Discussions BSW ISCO ? BSW field instability

Thank you