A Giant Shell of Ionized Gas Discovered near M82 with the Dragonfly Spectral Line Mapper Pathfinder
A Giant Shell of Ionized Gas Discovered near M82 with the Dragonfly Spectral Line Mapper Pathfinder
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DOI：
10.3847/1538-4357/ac50b6
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发表时间：
2022-03
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通讯作者：
D. Lokhorst;R. Abraham;I. Pasha;P. V. van Dokkum;Seery Chen;T. Miller;S. Danieli;J. Greco;Jielai Zhang;A. Merritt;C. Conroy
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作者：
D. Lokhorst;R. Abraham;I. Pasha;P. V. van Dokkum;Seery Chen;T. Miller;S. Danieli;J. Greco;Jielai Zhang;A. Merritt;C. Conroy
我们提出了一个巨大的电离气体云在恒星爆发星系M82领域的发现。来自云的发射在Hα和[N ii] λ6583中被看到，这些数据是通过一个小型探路者仪器获得的，该仪器用于测试将在蜻蜓光谱线测绘仪中实现的关键思想，蜻蜓光谱线测绘仪是蜻蜓长焦阵列的一个即将推出的超窄带成像版本。发现的云有一个贝壳状的形态，线性范围为0.8 °，位于M82西北0.6 °。在M81群的日心距离上，云的最长角范围对应于55 kpc，它到M82核心的投影距离是40 kpc。云团的平均Hα表面亮度为2 × 10−18 ergcm−2s−1arcsec−2。[N ii] λ6583/Hα谱线比值在整个云层中从[N ii]/Hα <$0.2到[N ii]/Hα <$1.0不等，在其东端发现较高的值。用Keck LRIS获得的后续光谱证实了云的存在，云中的屈服线比[N ii] λ6583/Hα = 0.340 ± 0.003，[S ii] λ6716，6731/Hα = 0.64 ± 0.03。这个巨大的物质云可能是通过潮汐相互作用或强大的恒星爆发从M82中升起的。或者，它可能是来自宇宙网的气体，可能是由M82的超级风沉淀下来的。需要更深入的数据来进一步测试这些想法。即将推出的Dragonfly光谱线测绘仪将有120个镜头，比用于获得此处所示数据的探路者仪器多40倍。
We present the discovery of a giant cloud of ionized gas in the field of the starbursting galaxy M82. Emission from the cloud is seen in Hα and [N ii] λ6583 in data obtained though a small pathfinder instrument used to test the key ideas that will be implemented in the Dragonfly Spectral Line Mapper, an upcoming ultranarrow-bandpass imaging version of the Dragonfly Telephoto Array. The discovered cloud has a shell-like morphology with a linear extent of 0.°8 and is positioned 0.°6 northwest of M82. At the heliocentric distance of the M81 group, the cloud’s longest angular extent corresponds to 55 kpc and its projected distance from the nucleus of M82 is 40 kpc. The cloud has an average Hα surface brightness of 2 × 10−18 ergcm−2s−1arcsec−2 . The [N ii] λ6583/Hα line ratio varies from [N ii]/Hα ∼ 0.2 to [N ii]/Hα ∼ 1.0 across the cloud, with higher values found in its eastern end. Follow-up spectra obtained with Keck LRIS confirm the existence of the cloud and yield line ratios of [N ii] λ6583/Hα = 0.340 ± 0.003 and [S ii] λλ6716, 6731/Hα = 0.64 ± 0.03 in the cloud. This giant cloud of material could be lifted from M82 by tidal interactions or by its powerful starburst. Alternatively, it may be gas infalling from the cosmic web, potentially precipitated by the superwinds of M82. Deeper data are needed to test these ideas further. The upcoming Dragonfly Spectral Line Mapper will have 120 lenses, 40× more than in the pathfinder instrument used to obtain the data presented here.