Near-extremal Kerr-like ECO in the Kerr/CFT Correspondence M. Zhahir Djogama (a*), Muhammad F. A. R. Sakti (c), and Freddy P. Zen (a,b)
a) Theoretical High Energy Physics Group, Department of Physics, Institut Teknologi Bandung, Bandung 40132, Indonesia
*zhahirdjo[at]gmail.com
b) Indonesia Center for Theoretical and Mathematical Physics (ICTMP), Institut Teknologi Bandung, Bandung 40132, Indonesia
c) High Energy Physics Theory Group, Department of Physics,
Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
Abstract
The Kerr/CFT correspondence initially introduced to study the quantum theory of gravity in the near-horizon geometry of an extreme Kerr black holes. The horizon can be replaced by a partially reflective membrane that comes from quantum gravitational corrections on the near-horizon region. In such modification, the black holes now can be seen as a horizonless exotic compact object (ECO). In this work, we consider the properties of Kerr-like ECOs in near-extremal condition using Kerr/CFT correspondence. We calculate the quasinormal modes and absorption cross-section in that background and compare the results with CFT dual computation. The corresponding dual CFT one needs to incorporate finite size/finite N effects in the dual CFT terminology to facilitate the reflective boundary condition. We find consistency between properties of the ECOs from gravity and CFT calculations. The QNMs is in line with non-extreme case, where the differences are in the length of the torus on which the dual CFT lives and phase shift of the perturbations. The absorption cross-section has oscillatory feature that start to disappear near extremal limit. We also obtain that the echo time-delay depends on the position of the membrane and extremality of the ECOs.
Keywords: Black holes, Exotic compact object, Kerr/CFT correspondence
