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arXiv · 2009.08464

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
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Abstract

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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Martin Wendt, Nicolas F. Bouché, Johannes Zabl, Ilane Schroetter, Sowgat Muzahid. 2020-09-17. MusE GAs FLOw and Wind (MEGAFLOW) V. The dust/metallicity-anisotropy of the Circum-Galactic Medium. https://doi.org/10.1093/mnras/stab049

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