The k-band hubble diagram for brightest cluster galaxies in x-ray clusters
Dec, 1997
15 pages
Published in:
- Mon.Not.Roy.Astron.Soc. 297 (1998) 128
e-Print:
- astro-ph/9712104 [astro-ph]
Report number:
- ICAST-97-16
View in:
Citations per year
Abstract: (arXiv)
This paper concerns the K band Hubble diagram for the brightest cluster galaxies (BCGs) in a sample of X-ray clusters covering the redshift range . We show that BCGs in clusters of high X-ray luminosity are excellent standard candles: the intrinsic dispersion in the raw K band absolute magnitudes of BCGs in clusters with erg s (in the 0.3 - 3.5 keV band) is no more than 0.22 mag, and is not significantly reduced by correcting for the BCG structure parameter, , or for X-ray luminosity. This is the smallest scatter in the absolute magnitudes of any single class of galaxy and demonstrates the homogeneity of BCGs in high- clusters. By contrast, we find that the brightest members of low- systems display a wider dispersion ( mag) in absolute magnitude than commonly seen in previous studies, which arises from the inclusion, in X-ray flux-limited samples, of poor clusters and groups which are usually omitted from low redshift studies of BCGs in optically rich clusters....[abstract shortened].. The BCGs in our high- clusters yield a value of if the cosmological constant . For a flat Universe we find with a 95 per cent confidence upper limit to the cosmological constant corresponding to . These results are discussed in the context of other methods used to constrain the density of the Universe, such as Type Ia supernovae.References(1)
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