arXiv 1102.18272011-02-09astro-ph.CO

宇宙红外背景光谱能量分布的测量

Measurements of the spectral energy distribution of the cosmic infrared background

Matthieu Béthermin, Hervé Dole

备注：: 9 pages, 1 figure, 1 table, proceedings of invited talk at CRF2010, DESY Hamburg, Nov 9-12 2010
发表信息：: PoS(CRF 2010)002

摘要：

河外背景光（EBL）是宇宙中所有结构形成过程的遗迹辐射。大约一半的背景，称为宇宙红外背景（CIB），在8-1000微米范围内发射，峰值约为150微米。这是由于恒星形成过程中的尘埃再发射和活动星系核的发射。CIB光谱能量分布（SED）制约着宇宙中恒星形成的模型。计算宇宙对TeV光子的不透明度也很有用。我们提出了不同类型的测量的CIB，并讨论他们的优点和缺点。1.通过COBE和其他实验测量绝对SED。这些测量受到分量分离（即，前景减法）的精度的限制。2.鲁棒的下限是由红外星系的河外星系数计数确定的。这些下限非常严格，最高可达100微米。在较大的波长下，仪器相当低的角分辨率强烈限制了数字计数的深度。“叠加”方法通过在另一波长处检测到的总体来确定在给定波长处发射的通量，并且提供在亚毫米范围内的严格下限。它与其他基于地图属性统计分析的方法如P（D）分析是互补的。3.最后，上限可以从河外源的高能谱中推导出来。这些上限给出了目前在近红外和中红外的良好约束。自大约15年前CIB发现以来，进展令人惊讶：SED更为人所知，其中大部分可以由星系（直接或间接）解释。前景也令人兴奋，普朗克和赫歇尔的波动分析，以及即将到来的任务。

英文摘要：

The extragalactic background light (EBL) is the relic emission of all processes of structure formation in the Universe. About half of this background, called the Cosmic Infrared Background (CIB) is emitted in the 8-1000 microns range, and peaks around 150 microns. It is due to the dust reemission from star formation processes and AGN emission. The CIB spectral energy distribution (SED) constraints the models of star formation in the Universe. It is also useful to compute the opacity of the Universe to the TeV photons. We present the different types of measurements of the CIB and discuss their strengths and weaknesses. 1. The absolute SED was measured by COBE, and by other experiments. These measurements are limited by the accuracy of the component separation, i.e. the foreground subtraction. 2. Robust lower limits are determined from the extragalactic number counts of infrared galaxies. These lower limits are very stringent up to 100 microns. At larger wavelengths, the rather low angular resolution of the instruments limits strongly the depth of the number counts. The "stacking" method determines the flux emitted at a given wavelength by a population detected at another wavelength, and provides stringent lower limits in the sub-mm range. It is complementary with other methods based on the statistical analysis of the map properties like the P(D) analysis. 3. Finally, upper limits can be derived from the high energy spectra of extragalactic sources. These upper limits give currently good constraints in the near- and mid-IR. Progress have been amazing since the CIB discovery about 15 years ago: the SED is much better known, and most of it can be accounted for by galaxies (directly or indirectly). Prospects are also exciting, with fluctuation analysis with Planck&Herschel, and forthcoming missions.

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