用ISOPHOT仪器测定宇宙远红外背景能级
Determination of the cosmic far-infrared background level with the ISOPHOT instrument
摘要：
宇宙红外背景（CIRB）主要由遥远星系的积分光组成。在远红外波段，目前对其表面亮度的估计是基于COBE卫星的测量。这些结果还需要其他仪器的独立确认。在本文中，我们得出的远红外CIRB使用的ISO卫星上的ISOPHOT仪器进行测量的估计。这些结果被用来进一步确认各个小组使用COBE数据得出的CIRB水平。我们研究了三个非常低的卷云发射区。用ISOPHOT仪器在90、150和180 μ m处观测到的表面亮度与来自Effelsberg射电望远镜的氢21 cm线数据相关。外推到零氢柱密度给出了河外信号加上黄道光的总和的估计。黄道光是用较短波长的ISOPHOT数据减去的。因此，所得到的远红外CIRB的估计值仅基于ISO测量。在150 - 180 μ m范围内，我们得到的CIRB值为1.08+-0.32+-0.30 MJy/sr，分别引用统计误差和系统误差。在90微米波段，我们得到一个2 σ上限为2.3兆焦耳/锶。来自ISOPHOT远红外地图的估计是一致的，与早期的COBE结果。
英文摘要：
The cosmic infrared background (CIRB) consists mainly of the integrated light of distant galaxies. In the far-infrared the current estimates of its surface brightness are based on the measurements of the COBE satellite. Independent confirmation of these results is still needed from other instruments. In this paper we derive estimates of the far-infrared CIRB using measurements made with the ISOPHOT instrument aboard the ISO satellite. The results are used to seek further confirmation of the CIRB levels that have been derived by various groups using the COBE data. We study three regions of very low cirrus emission. The surface brightness observed with the ISOPHOT instrument at 90, 150, and 180 um is correlated with hydrogen 21 cm line data from the Effelsberg radio telescope. Extrapolation to zero hydrogen column density gives an estimate for the sum of extragalactic signal plus zodiacal light. The zodiacal light is subtracted using ISOPHOT data at shorter wavelengths. Thus, the resulting estimate of the far-infrared CIRB is based on ISO measurements alone. In the range 150 to 180 um, we obtain a CIRB value of 1.08+-0.32+-0.30 MJy/sr quoting statistical and systematic errors separately. In the 90 um band, we obtain a 2-sigma upper limit of 2.3 MJy/sr. The estimates derived from ISOPHOT far-infrared maps are consistent with the earlier COBE results.
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