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Published February 2001 | Accepted Version + Published
Journal Article Open

On galaxy cluster sizes and temperatures


We show that the distribution of the sizes and temperatures of clusters can be used to constrain cosmological models. The size-temperature (ST) distribution predicted in a flat Gaussian cluster-abundance-normalized Ω₀ = 0.3 model agrees well with the fairly tight ST relation observed. A larger power-spectrum amplitude σ₈ would give rise to a larger scatter about the ST relation as would a larger value of Ω₀ and/or long non-Gaussian high-density tails in the probability density function. For Gaussian initial conditions, the ST distribution suggests a constraint σ₈Ω₀⁰·²⁶ ≃ 0.76. The ST relation is expected to get tighter at high redshifts. In the process, we derive a simple formula for the halo formation-redshift distribution for non-Gaussian models. We also suggest that the discrepancy between the naive zero-redshift ST relation and that observed may be owing, at least in part, to the fact that lower-mass clusters form over a wider range of redshifts. An Appendix derives an equation for the formation-redshift distribution of haloes.

Additional Information

© 2001 RAS. Accepted 2000 November 6. Received 2000 October 25; in original form 2000 August 3. Published: 11 February 2001. We thank P. Goldreich for asking questions that stimulated this investigation. This research was supported in part by the NSF under grant no. PHY94-07194 to the Institute for Theoretical Physics (Santa Barbara), where part of this research was completed. LV was supported by a TMR grant and thanks Caltech for hospitality. MK was supported in part by NSF AST-0096023, NASA NAG5-8506, and DoE DE-FG03-92-ER40701. JJM is supported by Chandra Fellowship grant PF8-1003, awarded through the Chandra Science Center. The Chandra Science Center is operated by the Smithsonian Astrophysical Observatory for NASA under contract NAS8-39073. AJB was supported by a PPARC studentship.

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Published - 321-1-L7.pdf

Accepted Version - 0007426.pdf


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