Ken Matsuno

Kaluza-Klein Black Holes with Squashed Horizons

We study geometrical structures of charged static black holes in the five-dimensional Einstein-Maxwell theory. The black holes we study have horizons in the form of squashed S 3 , and their asymptotic structure consists of a twisted S 1 bundle over the four-dimensional flat spacetime at the spatial infinity. The spacetime we consider is fully five-dimensional in the vicinity of the black hole and four-dimensional with a compact extra dimension at infinity.

Hawking radiation as tunneling from squashed Kaluza-Klein black hole

We discuss Hawking radiation from a five-dimensional squashed Kaluza-Klein black hole on the basis of the tunneling mechanism. A simple method, which was recently suggested by Umetsu, may be used to extend the original derivation by Parikh and Wilczek to various black holes. That is, we use the two-dimensional effective metric, which is obtained by the dimensional reduction near the horizon, as the background metric. Using the same method, we derive both the desired result of the Hawking temperature and the effect of the backreaction associated with the radiation in the squashed Kaluza-Klein black hole background.

Charged rotating Kaluza-Klein black holes in five dimensions

We construct a new charged rotating Kaluza-Klein black hole solution in the five-dimensional Einstein-Maxwell theory with a Chern-Simon term. The features of the solutions are also investigated. The spacetime is asymptotically locally flat, i.e., it asymptotes to a twisted S{sup 1} bundle over the four-dimensional Minkowski spacetime. The solution describe a non-BPS black hole rotating in the direction of the extra dimension. The solutions have the limits to the supersymmetric black hole solutions, a new extreme non-BPS black hole solution and a new rotating non-BPS black hole solution with a constant twisted S{sup 1} fiber.

Kaluza-Klein multi-black holes in five-dimensional Einstein-Maxwell theory

We construct Kaluza–Klein multi-black hole solutions on the Gibbons–Hawking multi-instanton space in the five-dimensional Einstein–Maxwell theory. We study the geometric properties of the multi-black hole solutions. In particular, unlike the Gibbons–Hawking multi-instanton solutions, each nut-charge is able to take a different value due to the existence of a black hole on it. The spatial cross section of each horizon is admitted to have the topology of a different lens space in addition to S3.

Kaluza-Klein-Kerr-Godel Black Holes Kaluza-Klein Black Holes with Rotations of Black Hole and Universe

Applying squashing transformation to the Kerr-Godel black hole solution, we present a new type of a rotating Kaluza-Klein black hole solution in the five-dimensional minimal supergravity. The new solution generated by the squashing transformation has no closed timelike curve outside the black hole horizons. The spacetime is asymptotically locally flat. One of the remarkable features is that the solution has two independent rotation parameters along an extra dimension associated with the black holes rotation and Godels rotation. The spacetime also admits the existence of two disconnected ergoregions, an inner ergoregion and an outer ergoregion. These two ergoregions can rotate in opposite directions as well as in the same direction. Subject Index: 450, 451

Rotating Kaluza-Klein multi-black holes with Gödel parameter

We obtain new five-dimensional supersymmetric rotating multi-Kaluza-Klein black hole solutions with the Goedel parameter in the Einstein-Maxwell system with a Chern-Simons term. These solutions have no closed timelike curve outside the black hole horizons. At infinity, the space-time is effectively four-dimensional. Each horizon admits various lens space topologies L(n;1)=S{sup 3}/Z{sub n} in addition to a round S{sup 3}. The space-time can have outer ergoregions disjointed from the black hole horizons, as well as inner ergoregions attached to each horizon. We discuss the rich structures of ergoregions.

Black holes on Eguchi-Hanson space in five-dimensional Einstein-Maxwell theory

We construct a pair of black holes on the Eguchi-Hanson space as a solution in the five-dimensional Einstein-Maxwell theory.

Geodetic Precession in Squashed Kaluza-Klein Black Hole Spacetimes

We investigate the geodetic precession effect of a parallelly transported spin vector along a circular geodesic in five-dimensional squashed Kaluza-Klein black hole spacetime. Then we derive the higher-dimensional correction of the precession angle to general relativity. We find that the correction is proportional to the square of (size of extra dimension)/(gravitational radius of central object)

Coalescence of rotating black holes on Eguchi-Hanson space

We obtain new charged rotating multi-black hole solutions on the Eguchi-Hanson space in the five-dimensional Einstein-Maxwell system with a Chern-Simons term and a positive cosmological constant. In the two-black holes case, these solutions describe the coalescence of two rotating black holes with the horizon topologies of S{sup 3} into a single rotating black hole with the horizon topology of the lens space L(2;1)=S{sup 3}/Z{sub 2}. We discuss the differences in the horizon areas between our solutions and the two-centered Klemm-Sabra solutions which describe the coalescence of two rotating black holes with the horizon topologies of S{sup 3} into a single rotating black hole with the horizon topology of S{sup 3}.

Supersymmetric black rings on Eguchi–Hanson space

We construct new supersymmetric black ring solutions on the Eguchi–Hanson base space as solutions of five-dimensional minimal supergravity. The solutions have the same two angular momentum components and the asymptotic structure on timeslices is asymptotically locally Euclidean. The S1-direction of the black ring is along the equator on a S2-bolt on the Eguchi–Hanson space. We also investigate the limit to a black hole, which describes the BMPV black hole with the topology of the lens space .