Supermassive black holes lead busy lives behind veils of dust that keep much of their activity under wraps. New X-ray observations challenge the notion that these cannibals, which reside at the cores of galaxies, finished growing soon after their host galaxies formed. Instead, these gravitational beasts--1 million to 1 billion times the mass of the sun--may pack on weight much more gradually, gobbling surrounding gas and stars for up to 2 billion years.
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