Metal enrichment in the Fermi bubbles as a probe of their origin

Yoshiyuki Inoue, Shinya Nakashima, Masaya Tahara, Jun Kataoka, Tomonori Totani, Yutaka Fujita, Yoshiaki Sofue

    研究成果: Article査読

    7 被引用数 (Scopus)


    The Fermi bubbles are gigantic gamma-ray structures in our Galaxy. The physical origin of the bubbles is still under debate. The leading scenarios can be divided into two categories. One is nuclear star-forming activity similar to extragalactic starburst galaxies and the other is past active galactic nucleus (AGN)-like activity of the Galactic center supermassive black hole. In this letter, we propose that metal abundance measurements will provide an important clue to probe their origin. Based on a simple spherically symmetric bubble model, we find that the generated metallicity and abundance patterns of the bubbles' gas strongly depend on assumed star formation or AGN activities. Star formation scenarios predict higher metallicities and abundance ratios of [O/Fe] and [Ne/Fe] than AGN scenarios do because of supernovae ejecta. Furthermore, the resultant abundance depends on the gamma-ray emission process because different mass injection histories are required for the different gamma-ray emission processes due to the acceleration and cooling time scales of non-thermal particles. Future X-ray missions such as ASTRO-H and Athena will give a clue to probe the origin of the bubbles through abundance measurements with their high energy resolution instruments.

    ジャーナルPublications of the Astronomical Society of Japan
    出版ステータスPublished - 2015 4月 8

    ASJC Scopus subject areas

    • 天文学と天体物理学
    • 宇宙惑星科学


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