アイテム詳細

要旨

The pure quadratic term of New Massive Gravity in three dimensions admits
asymptotically locally flat, rotating black holes. These black holes are
characterized by their mass and angular momentum, as well as by a hair of
gravitational origin. As in the Myers-Perry solution in dimensions greater than
five, there is no upper bound on the angular momentum. We show that,
remarkably, the equation for a massless scalar field on this background can be
solved in an analytic manner and that the quasinormal frequencies can be found
in a closed form. The spectrum is obtained requiring ingoing boundary
conditions at the horizon and an asymptotic behavior at spatial infinity that
provides a well-defined action principle for the scalar probe. As the angular
momentum of the black hole approaches zero, the imaginary part of the
quasinormal frequencies tends to minus infinity, migrating to the north pole of
the Riemann Sphere and providing infinitely damped modes of high frequency. We
show that this is consistent with the fact that the static black hole within
this family does not admit quasinormal modes for a massless scalar probe.