Abstract / Description of output
ONE of the most direct methods of constraining the epoch at which the
first galaxies formed-and thereby to constrain the age of the
Universe-is to identify and date the oldest galaxies at high redshift.
But most distant galaxies have been identified on the basis of their
abnormal brightness in some spectral region1-4 such selection
criteria are biased towards objects with pronounced nuclear activity or
young star-forming systems, in which the spectral signature of older
stellar populations will be concealed. Here we report the discovery of a
weak and extremely red radio galaxy (53W091) at z = 1.55, and present
spectroscopic evidence that its red colour results from a population of
old stars. Comparing our spectral data with models of the evolution of
stellar populations, we estimate that we are observing this galaxy at
least 3.5 Gyr after star-formation activity ceased. This implies an
extremely high formation redshift (z > 4) for 53W091 and, by
inference, other elliptical galaxies. Moreover, the age of 53W091 is
greater than the predicted age of the Universe at z = 1.55, under the
assumption of a standard Einstein-de Sitter cosmology (for any Hubble
constant greater than 50kms-1 Mpc-1), indicating
that this cosmological model can be formally excluded.
Original language | English |
---|---|
Pages (from-to) | 581-584 |
Journal | Nature |
Volume | 381 |
Issue number | 6583 |
Publication status | Published - 1 Jun 1996 |