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arXiv 2009.08464astro-ph.GA
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MusE GAs流和风(MEGAFLOW)V.环银河系介质的尘埃/金属性各向异性

MusE GAs FLOw and Wind (MEGAFLOW) V. The dust/metallicity-anisotropy of the Circum-Galactic Medium

Martin Wendt, Nicolas F. Bouché, Johannes Zabl, Ilane Schroetter, Sowgat Muzahid

摘要:

我们研究环银河系介质(CGM)的尘埃含量是否取决于类星体视线相对于星系主轴的位置,使用13个星系-MgII吸收体对(9 - 81 kpc距离)从MusE GAs流动和风(MEGAFLOW)调查在0.4 < z < 1.4。CGM的粉尘含量是使用紫外线和可见中阶梯光谱仪(UVES)数据从[Zn/Fe]获得的。当[Zn/Fe]的直接测量不可用时,我们从一种方法来估计灰尘的消耗,该方法包括解决多个单离子化离子(例如MnII,CrII,ZnII)的消耗,因为每个离子以不同的速率消耗灰尘颗粒。我们发现方位角和[Zn/Fe]之间呈正相关,Pearson r = 0.70 +/- 0.14。沿长轴的视线显示[Zn/Fe] < 0.5,而沿短轴的[Zn/Fe]> 0.8。这些结果表明,CGM沿短轴平均更丰富的金属(由~ 1德克斯)比气体位于沿星系的主轴提供的尘埃耗尽是金属丰度的代理。这种各向异性的分布是一致的流出和吸积流体动力学模拟的最新结果。

英文摘要:

We investigate whether the dust content of the circum-galactic medium (CGM) depends on the location of the quasar sightline with respect to the galaxy major-axis using 13 galaxy-MgII absorber pairs (9 - 81 kpc distance) from the MusE GAs FLOw and Wind (MEGAFLOW) survey at 0.4 < z < 1.4. The dust content of the CGM is obtained from [Zn/Fe] using Ultraviolet and Visual Echelle Spectrograph (UVES) data. When a direct measurement of [Zn/Fe] is unavailable, we estimate the dust depletion from a method which consists in solving for the depletion from multiple singly ionized ions (e.g. MnII, CrII, ZnII) since each ion depletes on dust grains at different rates. We find a positive correlation between the azimuthal angle and [Zn/Fe] with a Pearson's r = 0.70 +/- 0.14. The sightlines along the major axis show [Zn/Fe] < 0.5, whereas the [Zn/Fe] is > 0.8 along the minor axis. These results suggest that the CGM along the minor axis is on average more metal enriched (by ~ 1 dex) than the gas located along the major axis of galaxies provided that dust depletion is a proxy for metallicity. This anisotropic distribution is consistent with recent results on outflow and accretion in hydro-dynamical simulations.

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