Echoes from the Minkowski-core spacetime

Abstract: In this study, we construct a class of horizonless exotic compact objects (ECOs) with Minkowski core, classifying them as either photon sphere ECOs (PS ECOs) or photon sphere lacking ECOs (PL ECOs) based on photon sphere topology. Time domain analysis reveals that the dynamical evolution can be divided into three phases: the initial ringdown, the echo phase, and the final ringdown. The echo signals exhibit the periodic damping, with quantum effects significantly accelerating the echo dissipation and prompting an earlier transition to the long lived mode dominated phase. Furthermore, the QNM spectrum of the PS ECO exhibits fundamentally different behavior from that of BHs including the presence of long lived modes and the absence of overtone outbursts providing a clear spectroscopic signature distinguishing PS ECOs from BHs. This work is significant in providing new theoretical foundations and waveform features for identifying such quantum corrected ECOs, contributing critically to the understanding of quantum gravity effects.