CfA astronomer Igor Chilingarian led a team that has for the first time identified a set of galaxies with active nuclei hosting intermediate-mass black holes. They used optical and near-infrared galaxy surveys to identify candidate sources from the intensity and velocities of their atomic emission lines, selecting three hundred and five likely IMBH candidates. They then obtained X-ray measurements from the Chandra and/or XMM missions which confirmed that ten of these nuclei were IMBHs and were actively accreting. The least massive IMBH they discovered in their set of ten had thirty-six thousand solar-masses; the largest had about ten times more. Their discovery is remarkable not only because it marks the first conclusive detection of these elusive objects, but because it lends credence to the idea that stellar-mass black holes seeded the early universe, with many of them then growing into the supermassive monsters we see today. Reference: “A Population of Bona Fide Intermediate-mass Black Holes Identified as Low-luminosity Active Galactic Nuclei” by Igor V. Chilingarian, Ivan Yu. Katkov, Ivan Yu. Zolotukhin, Kirill A. Grishin, Yuri Beletsky, Konstantina Boutsia and David J. Osip, 6 August 2018, The Astrophysical Journal.DOI 10.3847/1538-4357/aad184
