New light on black holes

Discoveries over the past several years have taken the study of classical black holes out of the hands of relativists and into the realm of observational astronomy and astrophysics. We now know, beyond all reasonable doubt, that black holes are usually present in the nuclei of normal galaxies with masses millions to billions that of the sun. Stellar mass black holes, whose births may sometimes be marked by gamma-ray bursts, are also plentiful within our Galaxy and show many similar behaviors to their giant counterparts on correspondingly shorter timescales. These observations are forcing us to re-think how black holes release energy from accreting gas and power their radiant emission and outflowing jets and winds. Black holes also appear to account for a larger fraction of the luminosity budget of the Universe than previously thought and, consequently, are likely to have an important role in the formation of galaxies