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arXiv 2506.08082astro-ph.CO
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BAO尺度附近红移空间成团中的尺度依赖偏倚与模式耦合

Scale-dependent bias and mode coupling in redshift-space clustering near the BAO scale

Aseem Paranjape, Ravi K. Sheth

AI总结:

本研究针对现有BAO特征模型未考虑尺度依赖偏倚与模式耦合的不足,构建了包含这两种效应的拉普拉斯-高斯类模型,验证其可准确描述BAO尺度示踪物两点相关函数多极矩,为巡天观测建模提供支撑。

摘要:

红移空间中偏倚示踪物两点成团特征的重子声学振荡(BAO)特征可以用与模型无关的方式描述,该方法仅依赖如下假设:非线性增长会以高斯核近似抹平该特征,而高斯核由泽尔多维奇近似下引力驱动的整体流产生。近期一项验证了该结论的显式模型未考虑两个在当前巡天中极可能具有观测相关性的物理效应,即线性拉格朗日密度与速度偏倚的尺度依赖性,以及模式耦合效应。本文弥补了这一缺陷,证明一个包含上述效应的简单模型能够准确描述BAO尺度下真实示踪物样本两点相关函数(2pcf)的多极矩。结果表明,尺度依赖偏倚的效应对DESI这类巡天的建模十分重要,而模式耦合的效应相对次要。我们提出的尺度依赖偏倚与模式耦合模型,源于峰理论和泽尔多维奇近似的与模型无关的论证,属于“拉普拉斯-高斯”展开类,因此可直接纳入前述与模型无关的推断框架中。

英文摘要:

The baryon acoustic oscillation (BAO) feature in the 2-point clustering of biased tracers in redshift space can be described in a model-agnostic manner, relying only on the assumption that nonlinear growth approximately smears this feature with a Gaussian kernel sourced by gravitationally driven bulk flows as in the Zel'dovich approximation. An explicit model that demonstrated this in recent work did not account for two physical effects that are very likely observationally relevant in the context of ongoing surveys, namely, the scale-dependence of linear Lagrangian density and velocity bias and the effects of mode coupling. We rectify this shortcoming in this paper by showing that a simple model including these effects is able to accurately describe the multipoles of the 2pcf of realistic tracer samples at BAO scales. Our results indicate that the effects of scale-dependent bias will be important to model for surveys such as DESI, while those of mode coupling are relatively less significant. Our model for scale-dependent bias and mode coupling, which is motivated by model-agnostic arguments from peaks theory and the Zel'dovich approximation, lies in the class of `Laplace-Gauss' expansions, making it straightforward to incorporate these effects in the model-agnostic inference framework mentioned above.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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