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首页> 外文期刊>The Astrophysical journal >AN X-RAY AND OPTICAL STUDY OF MATTER DISTRIBUTION IN THE GALAXY CLUSTER A2319
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AN X-RAY AND OPTICAL STUDY OF MATTER DISTRIBUTION IN THE GALAXY CLUSTER A2319

机译：X射线和A2319星系物质分布的光学研究

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摘要

A new analysis of velocity distribution, optical photometry, and X-ray surface brightness from ROSAT Position Sensitive Proportional Counter data of the galaxy cluster A2319 is presented. The temperature profile recently derived from ASCA data by Markevitch is taken into account. A method to check the hydrostatic model in the presence of a temperature gradient is proposed. Consistency of the hydrostatic isothermal model and the explanation of the “β-discrepancy” are discussed. Galaxy and gas density pro- files of the main component A2319A are derived, allowing for the effect of the secondary component A2319B. The inadequacy of a polytropic model, which would produce a binding mass decrease with respect to the isothermal β-model, is discussed. A simple interpolation of the temperature profile pro- vides instead an increase of the binding mass and a lower baryon fraction, thus mitigating the “ baryon catastrophe.” Assuming as typical the value f_b ≈ 0.2, a comparison with the most recent estimate of Ω_b~nucl implies for the cosmological parameter Ωo ≈＜ 0.4.
机译：根据星系团A2319的ROSAT位置敏感比例计数器数据，对速度分布，光学测光和X射线表面亮度进行了新的分析。考虑了Markevitch最近从ASCA数据得出的温度曲线。提出了一种在温度梯度存在下检查静水模型的方法。讨论了静水恒温模型的一致性和“β差异”的解释。推导出主要成分A2319A的星系和气体密度分布，从而考虑了次要成分A2319B的影响。讨论了多向性模型的不足之处，该不足会导致等温β模型的结合质量降低。通过简单地对温度曲线进行插值，可以增加结合质量，并降低重子分数，从而减轻了“重子突变”。假设典型值f_b≈0.2，则与最新估计Ω_b〜nucl的比较意味着宇宙学参数Ωo≈＜0.4。

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