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Adsorption line Survey of H+3 in the Galactic Center: The Warm and Diffuse Gas in the Central Molecular Zone

银河系中心H 3 吸附线巡天：中心分子区温暖而弥散的气体

基本信息

批准号：
203319529
负责人：
Dr. Miwa Goto, Ph.D.
金额：
--
依托单位：
Lehrstuhl für beobachtende und experimentelle Astrophysik
依托单位国家：
德国
项目类别：
Priority Programmes
财政年份：
2011
资助国家：
德国
起止时间：
2010-12-31 至 2015-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/203319529?language=en
关键词：
Adsorption line Survey H+3 Galactic

项目摘要

H+3 is the most fundamental molecular ion in the universe. It plays a pivotal role in the interstellar chemistry for its large Langevin reaction rate in ion-neutral reactions. The vibrational transition of H+3 is a unique probe for high-temperature (50–500 K) low-density (50–200 cm−3) gas, that other molecules, for instance CO, are not sensitive. Using infrared H+3 lines, we have found a large reservoir of warm and diffuse gas in the Central Molecular Zone (CMZ) of our Galaxy. The gas has similar density with the diffuse clouds in the Galactic disk, but the temperature is much higher (~250K). The filling factor of the cloud in the CMZ is significantly larger than 0.1, which makes it a new major population of the medium in the Galactic center. The cosmic ray ionization rate of H2 is at least one order of magnitude higher (ζ >10−15 s−1) in the cloud than in any other part of the Galactic disk. High ζ is potentially important for the energetics of the Galactic center, as it may explain how the kinetic energy of gas is efficiently converted to the thermal energy. In this program, we will investigate the physical extent of the clouds, the temperature and density profile inside the CMZ, and eventually the origin of the cloud in the context of the large-scale evolution of the Milky Way Galaxy.

H+3是宇宙中最基本的分子离子。它在离子中性反应中具有很大的朗之万反应速率，在星际化学中起着举足轻重的作用。H+3的振动跃迁是高温（50-500 K）低密度（50-200 cm−3）气体的独特探针，其他分子，如CO，不敏感。利用红外H+3谱线，我们在银河系的中央分子带（CMZ）发现了一个巨大的温暖和弥漫的气体库。该气体的密度与银盘中的弥散云相似，但温度要高得多（~ 250 K）。CMZ中云的填充因子明显大于0.1，这使其成为银河系中心介质的新的主要群体。星云中H2的宇宙线电离率比银盘的任何其他部分至少高一个数量级（ε>10−15 s−1）。高的能量密度对于银河系中心的能量学是潜在的重要，因为它可以解释气体的动能如何有效地转化为热能。在这个项目中，我们将研究云的物理范围，CMZ内部的温度和密度分布，并最终在银河系大规模演化的背景下研究云的起源。