Spectral Signature of Cosmological Infall Around the First Quasars
Abstract
The massive galaxies hosting the earliest supermassive black holes only a billion years after the big bang are expected to be surrounded by a large volume of infalling gas. This infall is halted at the boundary of the host galactic halo by a shock. Here we show that this generic infall pattern imprints a unique signature on the Lyman-alpha emission-line profile of bright high-redshift quasars. Absorption by the infalling hydrogen modifies the intrinsic singly-peaked emission line shape into a doubly-peaked profile. Recent spectra of quasars with redshifts >5 show apparent evidence for this predicted shape. This evidence confirms for the first time the idea that the earliest known quasars reside in massive (>10^{12} solar mass) host halos. The inferred mass infall rates are consistent with the expected build-up of the quasar host galaxies over the age of the universe at that early epoch.Keywords
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