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arXiv 2409.03178astro-ph.CO
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空洞数目计数作为大尺度结构的宇宙学探针

Void Number Counts as a Cosmological Probe for the Large-Scale Structure

Yingxiao Song, Qi Xiong, Yan Gong, Furen Deng, Kwan Chuen Chan, Xuelei Chen, Qi Guo, Yun Liu, Wenxiang Pei

AI总结:

本文提出将空洞数目计数(VNC)作为宇宙学探针,利用CSST模拟光谱巡天数据在六个红移区间约束宇宙学参数,证明其约束能力与空洞尺寸函数方法相当,可用于研究大尺度结构。

摘要:

空洞数目计数(VNC)表示宇宙大尺度结构(LSS)中低密度区域的数目,我们提出将其作为一种有效的宇宙学探针。基于九天(Jiutian)模拟生成星系模拟星表,并考虑中国空间站望远镜(CSST)的光谱巡天策略与仪器设计——其极限星等可达约23 AB mag,光谱分辨率R≳200,天区覆盖面积为17,500平方度——我们使用分水岭算法在不对空洞形状作任何假设的条件下识别空洞,获得模拟空洞星表,并在从z=0.3到1.3的六个红移区间内得到VNC数据。我们使用马尔可夫链蒙特卡洛(MCMC)方法约束宇宙学参数和VNC参数。理论模型中的空洞线性低密度阈值δ_v在给定红移处被设为自由参数,以拟合VNC数据并探索其红移演化。我们发现,VNC能够正确提取宇宙学信息,其对宇宙学参数的约束强度与空洞尺寸函数(VSF)方法相当,在CSST全光谱巡天中可达到百分之几的水平。这是因为VNC对空洞形状不敏感,修正后的理论模型可以通过对空洞特征进行积分而更好地匹配数据,并且通过采用更简单的选择标准,可以将更多空洞纳入VNC分析,从而提高统计显著性。这表明VNC可以成为探索LSS的有效宇宙学探针。

英文摘要:

Void number counts (VNC) indicates the number of low-density regions in the large-scale structure (LSS) of the Universe, and we propose to use it as an effective cosmological probe. By generating the galaxy mock catalog based on Jiutian simulations and considering the spectroscopic survey strategy and instrumental design of the China Space Station Telescope (CSST), which can reach a magnitude limit $\sim$23 AB mag and spectral resolution $R\gtrsim200$ with a sky coverage 17,500 deg$^2$, we identify voids using the watershed algorithm without any assumption of void shape, and obtain the mock void catalog and data of the VNC in six redshift bins from $z=0.3$ to1.3. We use the Markov Chain Monte Carlo (MCMC) method to constrain the cosmological and VNC parameters. The void linear underdensity threshold $δ_{\rm v}$ in the theoretical model is set to be a free parameter at a given redshift to fit the VNC data and explore its redshift evolution. We find that, the VNC can correctly derive the cosmological information, and the constraint strength on the cosmological parameters is comparable to that from the void size function (VSF) method, which can reach a few percentage levels in the CSST full spectroscopic survey. This is because that, since the VNC is not sensitive to void shape, the modified theoretical model can match the data better by integrating over void features, and more voids could be included in the VNC analysis by applying simpler selection criteria, which will improve the statistical significance. It indicates that the VNC can be an effective cosmological probe for exploring the LSS.

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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