NASA Performs Headcount of Local Black Holes

This all-sky map contains all active supermassive black holes out to a distance of 400 million light years from Earth. This is an unbiased survey, and scientists are convinced that no active black hole (called AGN, for Active Galactic Nucleus) has gone uncounted. Shown here are all high-energy X-ray sources, which includes many star systems within our galaxy which are not part of the Swift black hole survey. The AGN are the light blue and green dots, largely "high" in the sky above and below the galactic plane. Credit: NASA/Swift/BAT/Markwardt et al.