Tidal deformability of ultracompact Schwarzschild stars and their approach to the black hole limit

Abstract

A well-known result in general relativity is that the tidal Love numbers of black holes vanish. In contrast, different configurations to a black hole may have non-vanishing Love numbers. For instance, it has been conjectured recently that the Love number of generic exotic compact objects (ECOs) shows a logarithmic behavior. Here we analyze the ultracompact Schwarzschild star which allows the compactness to cross and go beyond the Buchdahl limit. This Schwarzschild star has been shown to be a good black hole mimicker, moreover, it has been found that the Love number of these objects approaches zero as their compactness approaches the black hole limit. Here we complement those results, by showing that the Love number for these configurations follows an exponentially decaying behavior rather than the logarithmic behavior proposed for generic ECOs.