23
January 2003
The first quasars: gas fuelled
The Sloan Digital Sky Survey of high-redshift quasars revealed that a billion years after the Big Bang there were plenty of supermassive black holes in the Universe. How can objects a billion times the mass of the Sun be formed on such a cosmologically short timescale? Barkana and Loeb show that the rapid infalls of gas needed to feed black holes growing at such rapid rates would imprint a distinctive signature on the Lyman-a emission spectrum. And recent data do contain this signature, providing observational evidence for the presence of massive host galaxies, with haloes of dark matter, around the first generation of quasars.
Spectral signature of cosmological infall of gas around the first quasars
RENNAN BARKANA & ABRAHAM LOEB
Nature 421, 341–343 (2003); doi:10.1038/nature01330
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Astronomy: Feeding the first quasars
LAURA FERRARESE
Quasars, the oldest known objects in the Universe, are powered by gas falling into black holes at their centres. How black holes formed so early in time has been hard to explain, but a new model might have the answer.
Nature 421, 329–330 (2003); doi:10.1038/421329a
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