Gamma-ray emission from the Sagittarius dwarf spheroidal galaxy due to millisecond pulsars
Gamma-ray emission from the Sagittarius dwarf spheroidal galaxy due to millisecond pulsars
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DOI：
10.1038/s41550-022-01777-x
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发表时间：
2022-04
期刊：
影响因子：
14.1
通讯作者：
R. Crocker;O. Macias;D. Mackey;M. Krumholz;S. Ando;S. Horiuchi;M. Baring;C. Gordon;T. Venville;A. Duffy;Rui-zhi Yang;F. Aharonian;J. Hinton;D. Song;A. Ruiter;M. Filipović
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文献类型：
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作者：
R. Crocker;O. Macias;D. Mackey;M. Krumholz;S. Ando;S. Horiuchi;M. Baring;C. Gordon;T. Venville;A. Duffy;Rui-zhi Yang;F. Aharonian;J. Hinton;D. Song;A. Ruiter;M. Filipović
费米气泡是由费米伽马射线空间望远镜上的大面积望远镜收集的~1-100γGeV数据中发现的从银河系核心发出的巨大的 射线波瓣。之前的工作已经揭示了费米气泡中的亚结构，这被解释为银河系超大质量黑洞准直流出的标志。在这里，我们通过空间模板分析表明，与子结构中最亮的区域--所谓的蚕茧--相关的大部分γ射线发射很可能是由于人马座矮星球状星系(DSph)。这颗巨大的银河系卫星是从太阳系的位置通过费米气泡观看的。作为一个潮汐和冲撞压力剥离的残余物，人马座dSph没有正在形成的恒星，但我们仍然证明了矮星的毫秒脉冲星群体可以可信地提供γ-射线信号，我们的分析将其与其恒星模板相关联。测量到的光谱可以通过射手座dSph毫秒脉冲星注入的高能电子-正电子对对宇宙微波背景光子的逆康普顿散射，结合这些天体的磁层发射来自然解释。这一发现可信地表明，毫秒脉冲星在老恒星群中产生了显著的γ射线发射，可能会混淆银河系中心、仙女座星系和其他大质量银河系dsps等区域的间接暗物质搜索。
The Fermi bubbles are giant, γ-ray-emitting lobes emanating from the nucleus of the Milky Way discovered in ~1–100 GeV data collected by the Large Area Telescope on board the Fermi Gamma-Ray Space Telescope. Previous work has revealed substructure within the Fermi bubbles that has been interpreted as a signature of collimated outflows from the Galaxy’s supermassive black hole. Here we show via a spatial template analysis that much of the γ-ray emission associated with the brightest region of substructure—the so-called cocoon—is probably due to the Sagittarius dwarf spheroidal galaxy (dSph). This large Milky Way satellite is viewed through the Fermi bubbles from the position of the Solar System. As a tidally and ram-pressure stripped remnant, the Sagittarius dSph has no ongoing star formation, but we nevertheless demonstrate that the dwarf’s millisecond pulsar population can plausibly supply the γ-ray signal that our analysis associates with its stellar template. The measured spectrum is naturally explained by inverse Compton scattering of cosmic microwave background photons by high-energy electron–positron pairs injected by millisecond pulsars belonging to the Sagittarius dSph, combined with these objects’ magnetospheric emission. This finding plausibly suggests that millisecond pulsars produce significant γ-ray emission among old stellar populations, potentially confounding indirect dark-matter searches in regions such as the Galactic Centre, the Andromeda galaxy and other massive Milky Way dSphs.