Echoes from braneworld black holes
Ramit Dey, Sumanta Chakraborty, Niayesh Afshordi
Abstract
The holographic interpretation of the Randall-Sundrum model based on the adaptation of the $\mathrm{AdS}/\mathrm{CFT}$ correspondence to the braneworld scenario states that the black holes localized on the brane are quantum corrected. This can be better understood from the fact that the classical ${\mathrm{AdS}}_{5}$ bulk dynamics is dual to gravity coupled with conformal field theory (CFT) on the four-dimensional brane. Based on the backreaction of the CFT on the classical black hole geometry, localized on the brane, it is expected that there exist possible near-horizon modifications. This may result in the black hole horizon becoming partially reflective, thus giving rise to echoes in the ringdown signal in gravitational wave observations. In this paper, we investigate the existence of such echoes in the ringdown phase of a black hole localized on the brane, carrying a negative tidal charge, and establish the layout for future investigation of higher-dimensional effects in the ringdown signal. Confirmed detections of echoes at the current levels of instrumental sensitivity can constrain the dimensionless value of tidal charge to $|Q|\ensuremath{\lesssim}{M}^{2}$.