Tidal Love numbers of a nonexotic compact object with a thin shell

Abstract

As a possible alternative to black holes, horizonless compact objects have significant implications for gravitational-wave physics. In this work, we utilize the standard linearized theory of general relativity to calculate the quadrupolar tidal Love numbers of a nonexotic compact object with a thin shell proposed by Rosa and Piçarra. It is found that both types of tidal Love numbers are positive and increase with the initial radius for almost all values of the compactness parameter. Furthermore, they have an unexpected upper bound and vanish in the most compact configurations. As a result, this model is indeed a suitable mimicker of a black hole. However, we also observed that the speed of sound within the fluid on the shell diverges in the black hole limit.

7 two-column pages, 3 figures; v2: typos corrected; v3: matching the published version in PRD