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Astronomy

The age of the quasars

Nature volume 514, pages 43–44 (2014)Cite this article

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An infrared census of accreting supermassive black holes across a wide range of cosmic times indicates that the canonical understanding of how these luminous objects form and evolve may need to be adjusted.

Ask an astronomer when quasars were at their peak and they will probably tell you it was about 10 billion years ago, when the Universe was about one-third of its current size1,2. Before then, the quasar population was still growing along with other large structures in the young Universe; there has since been a steady decrease in quasar numbers. However, in a paper published in The Astrophysical Journal, Vardanyan et al.3 present results suggesting that this widely accepted picture may not be correct — or at least that it does not tell the whole story.

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Figure 1: The energy output of quasars over cosmic time.

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  1. Daniel Mortlock is in the Departments of Physics and of Mathematics, Imperial College London, London SW7 2AZ, UK.,

    Daniel Mortlock

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  1. Daniel Mortlock
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Correspondence to Daniel Mortlock.

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Mortlock, D. The age of the quasars. Nature 514, 43–44 (2014). https://doi.org/10.1038/514043a

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