The Isotropic Interplanetary Dust Cloud and Near-infrared Extragalactic Background Light Observed with COBE/DIRBE
The Isotropic Interplanetary Dust Cloud and Near-infrared Extragalactic Background Light Observed with COBE/DIRBE
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DOI：
10.3847/1538-4357/abad3d
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发表时间：
2020-08
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通讯作者：
K. Sano;S. Matsuura;Kazuma Yomo;Aoi Takahashi College of Science;Engineering;S. O. Mathematics;Physics;K. University;D. Physics;School of Materials Science;Kwansei Gakuin University;Department of Electrical Engineering;T. University;Astrobiology Center
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作者：
K. Sano;S. Matsuura;Kazuma Yomo;Aoi Takahashi College of Science;Engineering;S. O. Mathematics;Physics;K. University;D. Physics;School of Materials Science;Kwansei Gakuin University;Department of Electrical Engineering;T. University;Astrobiology Center
通过分析宇宙背景探测器（COBE）上漫射红外背景实验（DIRBE）的红外（IR）图，我们报道了对各向同性行星际尘埃（IPD）的观测。为了寻找各向同性IPD，我们根据太阳延伸角（柱）进行了新的分析，因为我们预计各向同性IPD的黄道光（ZL）强度会作为柱的函数而降低。我们使用覆盖64°的DIRBE周平均图，并在减去传统的ZL分量后检查剩余强度的λ依赖关系。我们发现残差的λ依赖，表明各向同性IPD的存在。然而，中红外柱依赖性与各向同性IPD模型在λ≤90°处不同，残差强度随ε的变化而增加。为了解释观测到的ε依赖关系，我们假设球状IPD云在离太阳越远的地方密度越高。我们通过减去球体分量来估计近红外河外背景光（EBL）的强度，并假设剩余亮度在12 μm处的光谱能量分布。在1.25 μm、2.2 μm和3.5 μm处，导出的EBL强度分别为、、和。EBL仍然比普通星系的综合光大几倍，这表明存在未知的河外光源。
We report observation of isotropic interplanetary dust (IPD) by analyzing the infrared (IR) maps of the Diffuse Infrared Background Experiment (DIRBE) on board the Cosmic Background Explorer (COBE) spacecraft. To search for the isotropic IPD, we perform new analysis in terms of the solar elongation angle (ϵ), because we expect the zodiacal light (ZL) intensity from the isotropic IPD to decrease as a function of ϵ. We use the DIRBE weekly averaged maps covering 64° ≲ ϵ ≲ 124° and inspect the ϵ dependence of residual intensity after subtracting conventional ZL components. We find the ϵ dependence of the residuals, indicating the presence of the isotropic IPD. However, the mid-IR ϵ dependence is different from that of the isotropic IPD model at ϵ ≳ 90°, where the residual intensity increases as a function of ϵ. To explain the observed ϵ dependence, we assume a spheroidal IPD cloud showing higher density farther away from the Sun. We estimate the intensity of the near-IR extragalactic background light (EBL) by subtracting the spheroidal component, assuming the spectral energy distribution from the residual brightness at 12 μm. The EBL intensity is derived as , , and at 1.25, 2.2, and 3.5 μm, respectively. The EBL is still a few times larger than the integrated light of normal galaxies, suggesting the existence of unaccounted-for extragalactic sources.