用COBE/DIRBE观测的各向同性行星际尘埃云和近红外河外背景光
The isotropic interplanetary dust cloud and near-infrared extragalactic background light observed with COBE/DIRBE
摘要：
通过分析COBE探测器上的漫红外背景实验（DIRBE）的红外图像，我们观测到了各向同性的行星际尘埃（IPD）。为了寻找各向同性IPD，我们在太阳伸长角（$ε$）方面进行了新的分析，因为我们预计来自各向同性IPD的黄道光（ZL）强度将作为$ε$的函数而降低。我们使用覆盖$64^\circ \lesssim ε\lesssim 124^\circ$的DIRBE周平均图，并在减去常规ZL分量后检查剩余强度的$ε$依赖性。我们发现$ε$依赖的残差，表明各向同性IPD的存在。然而，中红外$ε$依赖性不同于在$ε\gtrsim 90^\circ$的各向同性IPD模型，其中残余强度作为$ε$的函数增加。为了解释所观察到的$ε$依赖性，我们假设一个球状IPD云显示更高的密度更远离太阳。我们估计的近红外河外背景光（EBL）的强度减去球状分量，假设从$12\,{\rm μm}$的剩余亮度的光谱能量分布。EBL强度分别以$1.25$、$2.2$和$3.5\,{\rm μm}$推导为$45_{-8}^{+11}$、$21_{-4}^{+3}$和$15\pm3\,{\rm nWm^{-2}sr^{-1}}$。EBL仍然比正常星系的积分光大几倍，这表明存在不明的河外源。
英文摘要：
We report observation of isotropic interplanetary dust (IPD) by analyzing the infrared (IR) maps of Diffuse Infrared Background Experiment (DIRBE) onboard the Cosmic Background Explorer (COBE) spacecraft. To search for the isotropic IPD, we perform new analysis in terms of solar elongation angle ($ε$), because we expect zodiacal light (ZL) intensity from the isotropic IPD to decrease as a function of $ε$. We use the DIRBE weekly-averaged maps covering $64^\circ \lesssim ε\lesssim 124^\circ$ 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 $ε\gtrsim 90^\circ$, 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 further away from the sun. We estimate intensity of the near-IR extragalactic background light (EBL) by subtracting the spheroidal component, assuming the spectral energy distribution from the residual brightness at $12\,{\rm μm}$. The EBL intensity is derived as $45_{-8}^{+11}$, $21_{-4}^{+3}$, and $15\pm3\,{\rm nWm^{-2}sr^{-1}}$ at $1.25$, $2.2$, and $3.5\,{\rm μm}$, respectively. The EBL is still a few times larger than integrated light of normal galaxies, suggesting existence of unaccounted extragalactic sources.
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。
