TY - JOUR

T1 - Superradiance around rotating dilatonic black holes

AU - Koga, Jun ichirou

AU - Maeda, Kei ichi

N1 - Funding Information:
We would like to thank T. Tachizawa for useful discussions. This work was supported partially by the Grant-in-Aid for Scientific ResearchF und of the Ministry of Education, Science and Culture (No. 06302021 and No. 06640412)) and by Waseda University Grant for Special ResearchP rojects.

PY - 1994/12/1

Y1 - 1994/12/1

N2 - We consider a superradiance effect around rotating dilatonic black holes. We analyze two cases: one is an exact solution with the coupling constant α = 3, which effective action is reduced from the 5-dimensional Kaluza-Klein theory, and the other is a slowly rotating dilatonic black holes with arbitrary coupling constant. We find that there exists a critical value (α ∼ 1), which is predicted from a superstring model, and the superradiant emission rate with coupling larger than the critical value becomes much higher than the Kerr-Newman case (α = 0) in the maximally charged limit. Consequently, 4-dimensional primordial black holes in higher dimensional unified theories are either rotating but almost neutral or charged but effectively non-rotating.

AB - We consider a superradiance effect around rotating dilatonic black holes. We analyze two cases: one is an exact solution with the coupling constant α = 3, which effective action is reduced from the 5-dimensional Kaluza-Klein theory, and the other is a slowly rotating dilatonic black holes with arbitrary coupling constant. We find that there exists a critical value (α ∼ 1), which is predicted from a superstring model, and the superradiant emission rate with coupling larger than the critical value becomes much higher than the Kerr-Newman case (α = 0) in the maximally charged limit. Consequently, 4-dimensional primordial black holes in higher dimensional unified theories are either rotating but almost neutral or charged but effectively non-rotating.

UR - http://www.scopus.com/inward/record.url?scp=0040331316&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0040331316&partnerID=8YFLogxK

U2 - 10.1016/0370-2693(94)91293-9

DO - 10.1016/0370-2693(94)91293-9

M3 - Article

AN - SCOPUS:0040331316

VL - 340

SP - 29

EP - 34

JO - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

JF - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

SN - 0370-2693

IS - 1-2

ER -