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arXiv 2212.02569astro-ph.CO
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用宇宙空洞约束引力的挑战

Challenges in Constraining Gravity with Cosmic Voids

Christopher Wilson, Rachel Bean

AI总结:

本研究通过N体模拟比较nDGP、$f(R)$引力与GR的空洞统计,发现模拟星系示踪体消除大小函数差异,但四极矩对引力模型不敏感,GSM可准确重构$ξ_2$,且空洞四极矩是$β$的无偏估计量。

摘要:

我们使用N体模拟比较了nDGP和$f(R)$引力模型与GR中的空洞大小和成团统计量。我们展示了考虑从模拟星系目录而非仅暗物质晕导出的统计量至关重要。当使用暗物质晕识别空洞时,GR与$f(R)$模型在空洞大小函数上呈现的显著差异,在更现实地使用晕的模拟星系示踪体识别空洞时被消除。在$f(R)$和nDGP模型中,无论是晕识别还是模拟星系识别的空洞,其径向速度和速度弥散相对于GR均有所增强。尽管如此,我们发现从模拟星系示踪体导出的红移空间空洞四极矩在三种引力模型中惊人地相似。高斯流模型(GSM)被证明能准确重构修正引力模型中的$ξ_2$,我们采用GSM,利用函数导数方法,分析$ξ_2$对引力模型的不敏感性。假设线性理论,我们展示了在修正引力理论中,空洞四极矩是红移空间增长率参数$β=f/b$的无偏估计量。

英文摘要:

We compare void size and clustering statistics for nDGP and $f(R)$ gravity models and GR using N-body simulations. We show how it is critical to consider the statistics derived from mock galaxy catalogs rather than the dark matter halos alone. Marked differences between the void size functions for GR and $f(R)$ models which present when voids are identified using dark matter halos are removed when voids are identified, more realistically, from mock galaxy tracers of the halos. The void radial velocities and velocity dispersions in the $f(R)$ and nDGP models are enhanced relative to GR in both halos and mock galaxy identified voids. Despite this, we find that the redshift space void quadrupole moments derived from the mock galaxy tracers are strikingly similar across the three gravity models. The Gaussian Streaming Model (GSM) is shown to accurately reconstruct $ξ_2$ in modified gravity models and we employ the GSM, using a functional derivative approach, to analyze the insensitivity of $ξ_2$ to the gravity model. Assuming linear theory, we show the void quadrupole to be an unbiased estimator of the redshift space growth rate parameter $β=f/b$ in the modified gravity theories.

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