Study of the Cosmic Rays and Interstellar Medium in Local H i Clouds Using Fermi-LAT Gamma-Ray Observations
Study of the Cosmic Rays and Interstellar Medium in Local H i Clouds Using Fermi-LAT Gamma-Ray Observations
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DOI：
10.3847/1538-4357/ab6a99
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发表时间：
2020-02
期刊：
影响因子：
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通讯作者：
T. Mizuno;S. Abdollahi;Y. Fukui;K. Hayashi;T. Koyama;A. Okumura;H. Tajima;H. Yamamoto
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文献类型：
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作者：
T. Mizuno;S. Abdollahi;Y. Fukui;K. Hayashi;T. Koyama;A. Okumura;H. Tajima;H. Yamamoto
星际气体密度分布的准确估计对于理解星际介质（ISM）和银河宇宙线（CR）至关重要。为了了解局部环境中的ISM和CR，对第三象限中纬度地区的弥散γ射线发射进行了研究。利用费米大天区望远镜（LAT）0.1-25.6 GeV能区的γ射线数据和其他星际气体示踪剂如HI 4PI巡天数据及普朗克尘埃热辐射模型，分别对北方和南方区域进行了分析。研究了高尘温区的粉尘排放量随中性气柱总密度的变化规律，并在假设研究区中性气柱强度均匀的条件下，利用γ射线资料对中性气柱总密度/比值进行了标定。测得的100 MeV以上的积分γ射线发射率分别在北方和南方地区，支持在太阳系附近存在均匀的CR强度。虽然大多数气体可以被解释为具有等于或更高的自旋温度，但发现了一个以光学厚度为主的区域。
An accurate estimate of the interstellar gas density distribution is crucial to understanding the interstellar medium (ISM) and Galactic cosmic rays (CRs). To comprehend the ISM and CRs in a local environment, a study of the diffuse γ-ray emission in a midlatitude region of the third quadrant was performed. The γ-ray data in the 0.1–25.6 GeV energy range of the Fermi Large Area Telescope (LAT) and other interstellar gas tracers such as the HI4PI survey data and the Planck dust thermal emission model were used, and the northern and southern regions were analyzed separately. The variation of the dust emission with the total neutral gas column density was studied in high dust temperature areas, and the / ratio was calibrated using γ-ray data under the assumption of a uniform CR intensity in the studied regions. The measured integrated γ-ray emissivities above 100 MeV are and in the northern and southern regions, respectively, supporting the existence of a uniform CR intensity in the vicinity of the solar system. While most of the gas can be interpreted to be with a spin temperature of or higher, an area dominated by optically thick with was identified.