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arXiv 0910.4910astro-ph.CO
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寻找第一个星系:透镜或空白领域?

Looking for the first galaxies: Lensing or blank fields?

A. Maizy, J. Richard, M. A. De Leo, R. Pello, J. P. Kneib

摘要:

第一个星系的识别和研究仍然是观测宇宙学中最令人兴奋的课题之一。确定最佳的观测策略是一个非常重要的选择,以便建立一个具有代表性的高z(z>7)光谱确认源的样本,超过目前的观测极限。本文对6<z<12星系的鉴别和研究中透镜场和空白场的相对效率进行了精确的讨论。的检测效率和字段到字段的方差估计从直接模拟的空白和透镜字段的观察。沿视线方向存在的强透镜星团对观测到的源的数量有着巨大的影响,在典型的地基“浅层”观测中,放大率偏差为正(AB<~25.5)。正放大率偏差随源的红移而增大,随测量深度和测量面积的增大而减小。在z~0.1-0.3处达到透镜簇的最大效率。如果LBG的UV LF在z>~7处强烈演化,则与透镜场相比,在浅勘测中观察空白场特别低效。同样在这种情况下,在JWST的典型深度(AB~28-29)处预期的z>8源的数量在透镜作用中比在空白场中高得多(例如,对于AB<~28,因子为~10)。需要具有大视场的空白场巡天来证明LF在z>6-7处的亮端,而透镜星团对于探索LF的中端至暗端特别有用。

英文摘要:

The identification and study of the first galaxies remains one of the most exciting topics in observational cosmology. The determination of the best possible observing strategies is a very important choice in order to build up a representative sample of spectroscopically confirmed sources at high-z (z>7), beyond the limits of present-day observations. This paper is intended to precisely adress the relative efficiency of lensing and blank fields in the identification and study of galaxies at 6<z<12. The detection efficiency and field-to-field variance are estimated from direct simulations of both blank and lensing fields observations. The presence of a strong-lensing cluster along the line of sight has a dramatic effect on the number of observed sources, with a positive magnification bias in typical ground-based ``shallow'' surveys (AB<~25.5). The positive magnification bias increases with the redshift of sources and decreases with both depth of the survey and the size of the surveyed area. The maximum efficiency is reached for lensing clusters at z~0.1-0.3. Observing blank fields in shallow surveys is particularly inefficient as compared to lensing fields if the UV LF for LBGs is strongly evolving at z>~7. Also in this case, the number of z>8 sources expected at the typical depth of JWST (AB~28-29) is much higher in lensing than in blank fields (e.g. a factor of ~10 for AB<~28). Blank field surveys with a large field of view are needed to prove the bright end of the LF at z>6-7, whereas lensing clusters are particularly useful for exploring the mid to faint end of the LF.

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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