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arXiv 0802.2416astro-ph
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重子声学振荡光谱红移巡天中星系偏置的自校准

Self calibration of galaxy bias in spectroscopic redshift surveys of baryon acoustic oscillations

Pengjie Zhang

摘要:

重子声学振荡(BAO)是研究宇宙膨胀的有力工具,它揭示了宇宙尺度上难以捉摸的暗能量和引力。像大多数建议那样,通过有偏的示踪剂对底层物质密度场进行BAO测量,可以达到很高的统计精度。然而,可能的规模依赖偏差可能会导致不可忽略的系统误差,特别是对于最雄心勃勃的光谱调查提出。我们表明,在这些调查中,精确的光谱红移信息允许{ \it自我校准}的星系偏差和它的随机性,作为规模和红移的函数。通过红移畸变效应,可以同时测量星系的实空间功率谱、星系速度和速度。在BAO的相关尺度上,星系速度忠实地跟踪底层物质的速度。这个有价值的功能,而模型独立的方式来衡量星系的偏差和它的随机性,通过比较三个功率谱。对于平方公里阵列(SKA),这种自校准在统计上是准确的,以校正由偏置尺度依赖引起的BAO峰位置的1%电平偏移。此外,我们发现SKA能够在速度功率谱中检测到BAO,为BAO宇宙学打开了一个新的窗口。

英文摘要:

Baryon acoustic oscillation (BAO) is a powerful probe on the expansion of the universe, shedding light on elusive dark energy and gravity at cosmological scales. BAO measurements through biased tracers of the underlying matter density field, as most proposals do, can reach high statistical accuracy. However, possible scale dependence in bias may induce non-negligible systematical errors, especially for the most ambitious spectroscopic surveys proposed. We show that precision spectroscopic redshift information available in these surveys allows for {\it self calibration} of the galaxy bias and its stochasticity, as function of scale and redshift. Through the effect of redshift distortion, one can simultaneously measure the real space power spectra of galaxies, galaxy-velocity and velocity, respectively. At relevant scales of BAO, galaxy velocity faithfully traces that of the underlying matter. This valuable feature enables a rather model independent way to measure the galaxy bias and its stochasticity by comparing the three power spectra. For the square kilometer array (SKA), this self calibration is statistically accurate to correct for 1% level shift in BAO peak positions induced by bias scale dependence. Furthermore, we find that SKA is able to detect BAO in the velocity power spectrum, opening a new window for BAO cosmology.

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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