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arXiv 1012.4996astro-ph.CO
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AMI Sunyaev-Zel'dovich观测分析中的参数化效应

Parameterization Effects in the analysis of AMI Sunyaev-Zel'dovich Observations

The AMI Consortium, :, Malak Olamaie, Carmen Rodriguez-Gonzalvez, Matthew L. Davies, Farhan Feroz, Thomas M. O. Franzen, Keith J. B. Grainge, Michael P. Hobson,… 展开作者

The AMI Consortium, :, Malak Olamaie, Carmen Rodriguez-Gonzalvez, Matthew L. Davies, Farhan Feroz, Thomas M. O. Franzen, Keith J. B. Grainge, Michael P. Hobson, Natasha Hurley-Walker, Anthony N. Lasenby, Guy G. Pooley, Richard D. E. Saunders, Anna M. M. Scaife, Michel Schammel, Paul F. Scott, Timothy W. Shimwell, David J. Titterington, Elizabeth M. Waldram, Jonathan T. L. Zwart

摘要:

大多数Sunyaev-Zel 'dovich(SZ)和X射线分析的星系团试图限制集群的总质量和/或气体质量使用参数化模型和假设的球对称性和流体静力平衡。通过数值探索的概率分布的集群参数给出了模拟的干涉SZ数据的背景下,贝叶斯方法,并假设一个β模型的电子数密度,我们调查的能力,这个模型和分析返回模拟集群输入量通过三个rameterisation。在参数化I中,我们假设T是一个输入参数。我们发现,参数化我几乎不能约束集群参数。然后,我们调查参数化II和III,其中fg(r200)取代温度作为主要变量。在参数化II中,我们将M_T(r200)和T联系起来,假设流体静力平衡。我们发现,参数化II可以限制集群的物理参数,但温度估计是有偏见的低。在参数化III中,维里定理取代了流体静力平衡假设。我们发现,参数化III的集群属性的无偏估计的结果。我们使用广义NFW(GNFW)压力分布生成第二个模拟集群,并使用基于熵的模型对其进行分析,以考虑我们分析中的温度梯度,并改善集群气体密度分布。该模型还约束了团簇的物理参数,结果表明气体温度如预期的那样径向下降。平均集群总质量估计值也在模拟集群真实值的1 sigma范围内。然而,我们发现,至少在目前的实践中的干涉SZ分析,有两个模型之间的AMI活力没有差异。当然,随着文书的改进,这种情况可能会改变。

英文摘要:

Most Sunyaev--Zel'dovich (SZ) and X-ray analyses of galaxy clusters try to constrain the cluster total mass and/or gas mass using parameterised models and assumptions of spherical symmetry and hydrostatic equilibrium. By numerically exploring the probability distributions of the cluster parameters given the simulated interferometric SZ data in the context of Bayesian methods, and assuming a beta-model for the electron number density we investigate the capability of this model and analysis to return the simulated cluster input quantities via three rameterisations. In parameterisation I we assume that the T is an input parameter. We find that parameterisation I can hardly constrain the cluster parameters. We then investigate parameterisations II and III in which fg(r200) replaces temperature as a main variable. In parameterisation II we relate M_T(r200) and T assuming hydrostatic equilibrium. We find that parameterisation II can constrain the cluster physical parameters but the temperature estimate is biased low. In parameterisation III, the virial theorem replaces the hydrostatic equilibrium assumption. We find that parameterisation III results in unbiased estimates of the cluster properties. We generate a second simulated cluster using a generalised NFW (GNFW) pressure profile and analyse it with an entropy based model to take into account the temperature gradient in our analysis and improve the cluster gas density distribution. This model also constrains the cluster physical parameters and the results show a radial decline in the gas temperature as expected. The mean cluster total mass estimates are also within 1 sigma from the simulated cluster true values. However, we find that for at least interferometric SZ analysis in practice at the present time, there is no differences in the AMI visibilities between the two models. This may of course change as the instruments improve.

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