1. 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

2. 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.

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

4. Particle motion around Kerr BH
縄文式土器　　

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

6. Maximally rotating case
asymptote to
BH horizon
horizon

7. asymptotes to BH horizon “velocity”

8. not fine
tuned
Center of mass energy
can be very large

9. center of mass energy

10. on horizon
BSW (2009)

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

12. 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.

13. ISCO particles in
fine tuned !!

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

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

16. Higher dimensional case
ISCO does not exist in

17. 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

18. 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.

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

20. 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

21. 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

22. 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.

23. Discussions
BSW
ISCO ?
BSW
field instability

24. Thank you