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arXiv 1105.1463astro-ph.CO
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100和160 μ m宇宙红外本底各向异性和平均能级的精确测量

An accurate measurement of the anisotropies and mean level of the Cosmic Infrared Background at 100 and 160 um

Aurélie Pénin, Guilaine Lagache, Alberto Noriega-Crepo, Julien Grain, Marc-Antoine Miville-Deschênes, Nicolas Ponthieu, Peter Martin, Kevin Blagrave, Felix J. Lockman

摘要:

宇宙红外背景(CIB)各向异性的测量是研究星系演化和大尺度结构的有力手段。这些各向异性已经通过从远红外到毫米的大量实验测量。在大尺度上进行精确测量的主要障碍之一是银河尘埃排放对前景信号的污染。我们的目标是表明,我们可以消除银河卷云污染使用HI数据,从而准确地测量在CIB星暴星系的集群。我们使用ELAIS N1场在远红外(100和160μm)和无线电(21 cm)波长的观测结果。我们计算尘埃排放,跟踪远红外观测,HI气体跟踪21厘米的观测之间的相关性,并推导出尘埃发射率,使我们能够减去卷云发射的远红外地图。然后,我们推导出CIB各向异性的功率谱,以及它在100μm和160μm的平均水平。我们还结合了HI数据和Spitzer总功率模式绝对测量值来确定160μm处的CIB平均水平。我们发现B_(160)=0.77 \pm 0.04 \pm 0.12 MJ/sr,其中第一个误差是统计误差,第二个误差是系统误差。结合相关各向异性的B100/B160颜色,我们还导出了100 μm处的CIB平均值,B100=0.24 \pm 0.08 \pm 0.04 MJy/sr。这个测量值与最近的红外星系演化模型和Herschel/PACS数据所获得的值一致,但比以前的DIRBE测量值小得多。必须使用高角分辨率的Hi数据来准确地区分卷云和CIB辐射。在这样的河外磁场中,100 μm的IRAS图(以及Schlegel和合作者开发的图)受到CIB各向异性的高度污染,因此不能用作银河卷云示踪剂。

英文摘要:

The measurement of the anisotropies in the cosmic infrared background (CIB) is a powerful mean of studying the evolution of galaxies and large-scale structures. These anisotropies have been measured by a number of experiments, from the far-infrared to the millimeter. One of the main impediments to an accurate measurement on large scales is the contamination of the foreground signal by Galactic dust emission. Our goal is to show that we can remove the Galactic cirrus contamination using HI data, and thus accurately measure the clustering of starburst galaxies in the CIB. We use observations of the ELAIS N1 field at far-infrared (100 and 160μm) and radio (21 cm) wavelengths. We compute the correlation between dust emission, traced by far-infrared observations, and HI gas traced by 21cm observations, and derive dust emissivities that enable us to subtract the cirrus emission from the far-infrared maps. We then derive the power spectrum of the CIB anisotropies, as well as its mean level at 100μm and 160μm. We also combine the HI data and Spitzer total power mode absolute measurements to determine the CIB mean level at 160μm. We find B160=0.77\pm0.04\pm0.12MJy/sr,where the first error is statistical and the second systematic. Combining this measurement with the B100/B160 color of the correlated anisotropies, we also derive the CIB mean at 100 μm, B100=0.24\pm0.08\pm0.04 MJy/sr. This measurement is in line with values obtained with recent models of infrared galaxy evolution and Herschel/PACS data, but is much smaller than the previous DIRBE measurements. The use of high-angular resolution Hi data is mandatory to accurately differentiate the cirrus from the CIB emission. The 100 μm IRAS map (and thus the map developed by Schlegel and collaborators) in such extragalactic fields is highly contaminated by the CIB anisotropies and hence cannot be used as a Galactic cirrus tracer.

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