Evidence for Late-time Feedback from the Discovery of Multiphase Gas in a Massive Elliptical at z = 0.4
Evidence for Late-time Feedback from the Discovery of Multiphase Gas in a Massive Elliptical at z = 0.4
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DOI：
10.3847/2041-8213/abc48d
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发表时间：
2020-09
期刊：
影响因子：
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通讯作者：
F. Zahedy;Hsiao-Wen Chen;E. Boettcher;M. Rauch;K. Decker French;A. Zabludoff
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文献类型：
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作者：
F. Zahedy;Hsiao-Wen Chen;E. Boettcher;M. Rauch;K. Decker French;A. Zabludoff
我们报告了在z≈0以外的静止星系中首次探测到多相气体。观测使用了更明亮的双透镜类星体HE0047−1756图像来探测质量()椭圆透镜星系的星际介质。利用哈勃太空望远镜的宇宙起源光谱仪(COS)，我们获得了透镜类星体的中分辨率FUV光谱，并在投影距离d=4.6kpc的透镜ISM中发现了许多来自H2的吸收特征。H2柱的密度是分子气体的分数，与一些局部静止的星系大致一致。新的COS光谱还揭示了来自高度电离的物种Ovi和Nv的运动复杂吸收特征，它们的柱密度分别为logN(Ovi)和logN(Nv)，这是外部星系中已知的最高水平。假设高电离吸收特征起源于星系周围的热晕辐射冷却的瞬变暖相(T∼105K)，我们推导出质量吸积率为。透镜中没有恒星的形成表明，这种流动的大部分返回到热晕，这意味着加热率为。来自演化的恒星群(主要是SNE Ia，但也有来自AGB恒星的风)的持续加热可能足以防止ISM中大量积累冷气体，即使在没有来自活动核的强烈反馈的情况下也是如此。
We report the first detection of multiphase gas within a quiescent galaxy beyond z ≈ 0. The observations use the brighter image of doubly lensed QSO HE 0047−1756 to probe the interstellar medium (ISM) of the massive ( ) elliptical lens galaxy at . Using Hubble Space Telescope's Cosmic Origins Spectrograph (COS), we obtain a medium-resolution FUV spectrum of the lensed QSO and identify numerous absorption features from H2 in the lens ISM at projected distance d = 4.6 kpc. The H2 column density is with a molecular gas fraction of , roughly consistent with some local quiescent galaxies. The new COS spectrum also reveals kinematically complex absorption features from highly ionized species O vi and N v with column densities log N(O vi) and log N(N v) , among the highest known in external galaxies. Assuming the high-ionization absorption features originate in a transient warm (T ∼ 105 K) phase undergoing radiative cooling from a hot halo surrounding the galaxy, we infer a mass accretion rate of . The lack of star formation in the lens suggests that the bulk of this flow is returned to the hot halo, implying a heating rate of . Continuous heating from evolved stellar populations (primarily SNe Ia but also winds from AGB stars) may suffice to prevent a large accumulation of cold gas in the ISM, even in the absence of strong feedback from an active nucleus.