Searching for stellar mass black holes in the solar neighborhood

We propose a search strategy for isolated stellar mass black holes in the solar neighborhood using information from the Sloan Digital Sky Survey. Accretion of the interstellar medium onto an isolated black hole is expected to result in a blended, thermal synchrotron spectrum, roughly flat from the optical to the far-infrared. We find that the Sloan Survey will be sensitive to isolated black holes in the range 1-100 M. out to a few hundred parsecs. We find that multiband photometry can distinguish black holes from field stars, with black holes having colors similar to QSOs. The holes may then be isolated from QSOs because they have a featureless spectrum with no emission lines. The Sloan Survey will likely find hundreds of objects that meet these criteria, and to reduce the number of candidates we suggest other selection criteria such as infrared observations and proper-motion measurements. If no black hole candidates are found in this survey, important limits can be placed on the local density of black holes and the halo fraction in black holes.