2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/213539Gravitational microlensing has been employed to identify massive halo objects by their amplification of distant sources; MACHO searches have studied event times $2 h \lesssim t_0 \lesssim 2 y$ corresponding masses in the range $10^{-6} M_{\odot} \lesssim M \lesssim 100 M_{\odot}$. We suggest that larger masses up to $10^6 M_{\odot}$ are also of considerable interest. It has not been excluded that there is a significant number of halo black holes with such high masses as suggested by cosmological entropy considerations and potentially detectable by high longevity microlensing events.Table clarifiedGeneral Relativity and Quantum CosmologyAstrophysicsHigh Energy Physics - PhenomenologyHigh Energy Physics - Theorytext