Figuring Out Gas & Galaxies in Enzo (FOGGIE). II. Emission from the z = 3 Circumgalactic Medium

Abstract

Observing the circumgalactic medium (CGM) in emission provides 3D maps of the spatial and kinematic extent of the gas that fuels galaxies and receives their feedback. We present mock emission-line maps of highly resolved CGM gas from the Figuring Out Gas & Galaxies in Enzo (FOGGIE) project and link these maps back to physical and spatial properties of the gas. In particular, we examine the ionization source leading to most O vi emission and how resolution affects the physical properties of the gas generating the emission. Finally, when increasing the spatial resolution alone, the total luminosity of the line emission increases by an order of magnitude for some lines considered. Current integral field unit instruments like Keck Cosmic Web Imager and Multi Unit Spectroscopic Explorer should be able to detect the brightest knots and filaments of such emission, and use this to infer the bulk kinematics of the CGM gas with respect to the galaxy. We conclude that the spatial resolution of simulated CGM gas can significantly influence the distribution of gas temperatures, densities, and metallicities that contribute to a given observable region. Greater spatial resolution than has been typically included in cosmological simulations to date is needed to properly interpret observations in terms of the underlying gas structure driving emission.

A Giant Lyα Nebula and a Small-scale Clumpy Outflow in the System of the Exotic Quasar J0952+0114 Unveiled by MUSE∗

“…measured in a consistent way and spatially resolved on extended scales. In general, the bi-dimensional distributions of He II/Lyα and C IV/Lyα line ratios are not homogeneous, as also suggested by previous observations and theoretical works (C19, Corlies et al 2018;McCourt et al 2018, among others). Particularly, ratios in the inner region are lower and more ordered than in the outer parts, where these values tend to be relatively higher and less spatially structured.…”

Project AMIGA: The Circumgalactic Medium of Andromeda*

“…The individual small-scale structures that contribute to the observed absorption profiles can therefore be resolved. These small-scale structures that become only apparent in highresolution simulations are hosts to a significant amount of cool gas, enhancing the column densities in especially the low ionization state of the gas (Peeples et al 2019;Corlies et al 2020; see also Hummels et al 2019;Rhodin et al 2019;van de Voort et al 2019).…”

“…New high-resolution, zoom-in simulations employ explicit treatments of the multiple gas-phase nature and feedback from stellar population models (e.g., Hopkins et al 2014Hopkins et al , 2018. It is also becoming clear that high resolution not only inside the galaxies but also in their CGM is required to capture more accurately the complex processes in the cool CGM, such as metal mixing (Hummels et al 2019;Peeples et al 2019;Suresh et al 2019;van de Voort et al 2019;Corlies et al 2020).…”

simba: the average properties of the circumgalactic medium of 2 ≤ z ≤ 3 quasars are determined primarily by stellar feedback

“…Indeed, the size of high-column density clouds in the aforementioned observations would require a cell size of 140 pc in AMR simulations and a resolution better than 4 M in SPH codes (Crighton et al 2015; see also Agertz et al 2007;Stern et al 2016;McCourt et al 2018). On the other hand, recent zoom-in simulations built upon the moving-mesh code Arepo were able to achieve a uniform resolution within the CGM of 1 ckpc (van de Voort et al 2019), while zoom-in simulations utilizing AMR codes could resolve even ∼ 500 cpc scales (Hummels et al 2019;Peeples et al 2019;Corlies et al 2018). A length scale of 500 cpc corresponds to ∼ 165 pc at z ≈ 2.4, which is about the resolution target for AMR codes that Crighton et al (2015) argued for.…”