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Virialization of the Inner CGM in the FIRE Simulations and Implications for Galaxy Disks, Star Formation, and Feedback

Stern, Jonathan; Faucher-Giguère, Claude-André; Fielding, Drummond; Quataert, Eliot; Hafen, Zachary; Gurvich, Alexander B.; Ma, Xiangcheng; Byrne, Lindsey; El-Badry, Kareem; Anglés-Alcázar, Daniel; Chan, T.K.; Feldmann, Robert; Kereš, Dušan; Wetzel, Andrew; Murray, Norman; Hopkins, Philip F.

Virialization of the Inner CGM in the FIRE Simulations and Implications for Galaxy Disks, Star Formation, and Feedback Thumbnail


Authors

Jonathan Stern

Claude-André Faucher-Giguère

Drummond Fielding

Eliot Quataert

Zachary Hafen

Alexander B. Gurvich

Xiangcheng Ma

Lindsey Byrne

Kareem El-Badry

Daniel Anglés-Alcázar

Robert Feldmann

Dušan Kereš

Andrew Wetzel

Norman Murray

Philip F. Hopkins



Abstract

We use the FIRE-2 cosmological simulations to study the formation of a quasi-static, virial-temperature gas phase in the circumgalactic medium (CGM) at redshifts 0 < z < 5 and how the formation of this virialized phase affects the evolution of galactic disks. We demonstrate that when the halo mass crosses ∼1012 M⊙, the cooling time of shocked gas in the inner CGM (∼0.1Rvir, where Rvir is the virial radius) exceeds the local free-fall time. The inner CGM then experiences a transition from on average subvirial temperatures (T ≪ Tvir), large pressure fluctuations, and supersonic inflow/outflow velocities to virial temperatures (T ∼ Tvir), uniform pressures, and subsonic velocities. This transition occurs when the outer CGM (∼0.5Rvir) is already subsonic and has a temperature ∼Tvir, indicating that the longer cooling times at large radii allow the outer CGM to virialize at lower halo masses than the inner CGM. This outside-in CGM virialization scenario is in contrast with inside-out scenarios commonly envisioned based on more idealized simulations. We demonstrate that inner CGM virialization coincides with abrupt changes in the central galaxy and its stellar feedback: the galaxy settles into a stable rotating disk, star formation transitions from "bursty" to "steady," and stellar-driven galaxy-scale outflows are suppressed. Our results thus suggest that CGM virialization is initially associated with the formation of rotation-dominated thin galactic disks, rather than with the quenching of star formation as often assumed.

Citation

Stern, J., Faucher-Giguère, C., Fielding, D., Quataert, E., Hafen, Z., Gurvich, A. B., …Hopkins, P. F. (2021). Virialization of the Inner CGM in the FIRE Simulations and Implications for Galaxy Disks, Star Formation, and Feedback. Astrophysical Journal, 911(2), Article 88. https://doi.org/10.3847/1538-4357/abd776

Journal Article Type Article
Acceptance Date Dec 28, 2020
Online Publication Date Apr 19, 2021
Publication Date Apr 20, 2021
Deposit Date Jan 11, 2022
Publicly Available Date Jan 11, 2022
Journal Astrophysical Journal
Print ISSN 0004-637X
Electronic ISSN 1538-4357
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 911
Issue 2
Article Number 88
DOI https://doi.org/10.3847/1538-4357/abd776

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Copyright Statement
© 2021. The American Astronomical Society. All rights reserved.





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