The fates of the circumgalactic medium in the FIRE simulations

Hafen, Zachary; Faucher-Giguère, Claude André; Anglés-Alcázar, Daniel; Stern, Jonathan; Kereš, Dušan; Hummels, Cameron; Esmerian, Clarke J.; Garrison-Kimmel, Shea; El-Badry, Kareem; Wetzel, Andrew; Chan, T. K.; Hopkins, Philip F.; Murray, Norman

doi:10.1093/mnras/staa902

Cited by 67 publications

(68 citation statements)

References 89 publications

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“…rounding the ∼L galaxies we analyze (e.g., Stern et al 2019;Hafen et al 2020). Some of the inflowing gas can also correspond to the recycling of gas previously ejected by winds (Oppenheimer et al 2010;Anglés-Alcázar et al 2017).…”

Section: Vertical Profiles Of Bulk Velocities and Velocity Dispersionsmentioning

confidence: 98%

Pressure balance in the multiphase ISM of cosmologically simulated disc galaxies

Gurvich

Faucher-Giguère

Richings

et al. 2020

Monthly Notices of the Royal Astronomical Society

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Pressure balance plays a central role in models of the interstellar medium (ISM), but whether and how pressure balance is realized in a realistic multiphase ISM is not yet well understood. We address this question using a set of FIRE-2 cosmological zoom-in simulations of Milky Way-mass disk galaxies, in which a multiphase ISM is self-consistently shaped by gravity, cooling, and stellar feedback. We analyze how gravity determines the vertical pressure profile as well as how the total ISM pressure is partitioned between different phases and components (thermal, dispersion/turbulence, and bulk flows). We show that, on average and consistent with previous more idealized simulations, the total ISM pressure balances the weight of the overlying gas. Deviations from vertical pressure balance increase with increasing galactocentric radius and with decreasing averaging scale. The different phases are in rough total pressure equilibrium with one another, but with large deviations from thermal pressure equilibrium owing to kinetic support in the cold and warm phases, which dominate the total pressure near the midplane. Bulk flows (e.g., inflows and fountains) are important at a few disk scale heights, while thermal pressure from hot gas dominates at larger heights. Overall, the total midplane pressure is well-predicted by the weight of the disk gas, and we show that it also scales linearly with the star formation rate surface density (ΣSFR). These results support the notion that the Kennicutt-Schmidt relation arises because ΣSFR and the gas surface density (Σg) are connected via the ISM midplane pressure.

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Section: Vertical Profiles Of Bulk Velocities and Velocity Dispersionsmentioning

confidence: 98%

Pressure balance in the multiphase ISM of cosmologically simulated disc galaxies

Gurvich

Faucher-Giguère

Richings

et al. 2020

Monthly Notices of the Royal Astronomical Society

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“…While Project AMIGA is dedicated to understanding the CGM of M31, our survey also provides a unique probe of the dwarf galaxies found in the halo of M31. In particular, we have the opportunity to assess whether the CGM of dwarf satellites plays an important role in the CGM of the host galaxy, as studied by cosmological and idealized simulations(e.g., Anglés-Alcázar et al 2017;Bustard et al 2018;Hafen et al 2019Hafen et al , 2020. When considering the dwarf galaxies in our analysis, we have two main goals: (1) to determine whether the velocity distributions of the dwarfs and the absorbers are similar, and (2) to assess whether some of the absorption observed toward the QSOs could be associated directly with the dwarfs, either as gas that is gravitationally bound or as gas that has been recently stripped.…”

Section: M31 Dwarf Galaxy Satellitesmentioning

confidence: 99%

“…In the CR run, collisional ionization and photoionization contribute comparably to the O VI mass at radii 50 <R<200 kpc (Ji et al 2020). The actual origins of the CGM in terms of gas flows in FIRE-2 simulations without magnetic fields or CRs were analyzed in Hafen et al (2020), although the results are expected to be similar for simulations with MHD only. In these simulations, O VI exists as part of a well-mixed hot halo, with contributions from all the primary channels of CGM mass growth: IGM accretion, wind, and contributions from satellite halos (reminiscent of the Eris2 simulations; see above and Shen et al 2013).…”

Section: Quantitative Comparison In the Cgm Variation Betweenmentioning

confidence: 99%

Project AMIGA: The Circumgalactic Medium of Andromeda*

Lehner

Berek

Howk

et al. 2020

ApJ

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Project AMIGA (Absorption Maps In the Gas of Andromeda) is a survey of the circumgalactic medium (CGM) of Andromeda (M31, R vir ;300 kpc) along 43 QSO sightlines at impact parameters 25 R569 kpc (25 at RR vir). We use ultraviolet absorption measurements of Si II, Si III, Si IV, C II, and C IV from the Hubble Space Telescope/Cosmic Origins Spectrograph and O VI from the Far Ultraviolet Spectroscopic Explorer to provide an unparalleled look at how the physical conditions and metals are distributed in the CGM of M31. We find that Si III and O VI have a covering factor near unity for R1.2 R vir and 1.9 R vir , respectively, demonstrating that M31 has a very extended ∼10 4-10 5.5 K ionized CGM. The metal and baryon masses of the 10 4-10 5.5 K CGM gas within R vir are 10 8 and 4×10 10 (Z/0.3 Z e) −1 M e , respectively. There is not much azimuthal variation in the column densities or kinematics, but there is with R. The CGM gas at R0.5 R vir is more dynamic and has more complicated, multiphase structures than at larger radii, perhaps a result of more direct impact of galactic feedback in the inner regions of the CGM. Several absorbers are projected spatially and kinematically close to M31 dwarf satellites, but we show that those are unlikely to give rise to the observed absorption. Cosmological zoom simulations of ∼L * galaxies have O VI extending well beyond R vir as observed for M31 but do not reproduce well the radial column density profiles of the lower ions. However, some similar trends are also observed, such as the lower ions showing a larger dispersion in column density and stronger dependence on R than higher ions. Based on our findings, it is likely that the Milky Way has a ∼10 4-10 5.5 K CGM as extended as for M31 and their CGM (especially the warm-hot gas probed by O VI) are overlapping.

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“…For example, simulations from Shen et al (2013) show that gas inflows are enriched to metallicities of only a tenth solar by previous episodes of star formation in the main host and in nearby dwarfs. Hafen et al (2020) Gas metallicity as a function of radial velocity, with the vertical line demarcating inflow (< 0) versus outflow (> 0). We stack together ∼70 galaxies from TNG50 at z = 0.5 with stellar mass M 10 10 ± 0.1 M , and include all sightlines with an impact parameter 100 ± 10 kpc, showing that outflows have preferentially higher metallicity than inflows, and occur more aligned with the minor axis of galaxies (larger azimuthal angles, as indicated by the colour).…”

Section: Gas Metallicitymentioning

confidence: 99%

“…Indeed gas that accretes on to a galaxy can later be ejected back into the CGM by galactic winds, while gas which was ejected from haloes can later re-accrete on to the CGM. Therefore, metal-rich outflows recycle through the CGM and mix with the accreting metal-poor gas (Oppenheimer et al 2010b;Rubin et al 2012;Anglés-Alcázar et al 2017;Zheng et al 2017;Hafen et al 2019Hafen et al , 2020. Despite the complexity of the physical processes at play, Fig.…”

Section: Fiducial Galaxy Sample and Analysismentioning

confidence: 99%

Predictions for the angular dependence of gas mass flow rate and metallicity in the circumgalactic medium

Péroux

Nelson

Voort

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We use cosmological hydrodynamical simulations to examine the physical properties of the gas in the circumgalactic media (CGM) of star-forming galaxies as a function of angular orientation. We utilise TNG50 of the IllustrisTNG project, as well as the EAGLE simulation to show that observable properties of CGM gas correlate with azimuthal angle, defined as the galiocentric angle with respect to the central galaxy. Both simulations are in remarkable agreement in predicting a strong modulation of flow rate direction with azimuthal angle: inflow is more substantial along the galaxy major axis, while outflow is strongest along the minor axis. The absolute rates are noticeably larger for higher ($\log {(M_\star / \rm {M}_\odot )} \sim 10.5$) stellar mass galaxies, up to an order of magnitude compared to $\dot{M} \lesssim 1$ M⊙ yr−1 sr−1 for $\log {(M_\star / \rm {M}_\odot )}\sim 9.5$ objects. Notwithstanding the different numerical and physical models, both TNG50 and EAGLE predict that the average metallicity of the CGM is higher along the minor versus major axes of galaxies. The angular signal is robust across a wide range of galaxy stellar mass $8.5 < \log {(M_\star / \rm {M}_\odot )} < 10.5$ at z < 1. This azimuthal dependence is particularly clear at larger impact parameters b ≥ 100 kpc. Our results present a global picture whereby, despite the numerous mixing processes, there is a clear angular dependence of the CGM metallicity. We make forecasts for future large survey programs that will be able to compare against these expectations. Indeed, characterising the kinematics, spatial distribution and metal content of CGM gas is key to a full understanding of the exchange of mass, metals, and energy between galaxies and their surrounding environments.

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The fates of the circumgalactic medium in the FIRE simulations

Cited by 67 publications

References 89 publications

Pressure balance in the multiphase ISM of cosmologically simulated disc galaxies

Pressure balance in the multiphase ISM of cosmologically simulated disc galaxies

Project AMIGA: The Circumgalactic Medium of Andromeda*

Predictions for the angular dependence of gas mass flow rate and metallicity in the circumgalactic medium

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