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.
Published - 321-1-L7.pdf
Accepted Version - 0007426.pdf