Figuring Out Gas & Galaxies In Enzo (FOGGIE) V: The Virial Temperature Does Not Describe Gas in a Virialized Galaxy Halo

Abstract

The classical definition of the virial temperature of a galaxy halo excludes a fundamental contribution to the energy partition of the halo: the kinetic energy of non-thermal gas motions. Using simulations of low-redshift, $\sim L^{\ast }$ galaxies from the FOGGIE project (Figuring Out Gas & Galaxies In Enzo) that are optimized to resolve low-density gas, we show that the kinetic energy of non-thermal motions is roughly equal to the energy of thermal motions. The simulated FOGGIE halos have $\sim 2\times$ lower bulk temperatures than expected from a classical virial equilibrium, owing to significant non-thermal kinetic energy that is formally excluded from the definition of $T_{\mathrm{vir}}$. We derive a modified virial temperature explicitly including non-thermal gas motions that provides a more accurate description of gas temperatures for simulated halos in virial equilibrium. Strong bursts of stellar feedback drive the simulated FOGGIE halos out of virial equilibrium, but the halo gas cannot be accurately described by the standard virial temperature even when in virial equilibrium. Compared to the standard virial temperature, the cooler modified virial temperature implies other effects on halo gas: (i) the thermal gas pressure is lower, (ii) radiative cooling is more efficient, (iii) O VI absorbing gas that traces the virial temperature may be prevalent in halos of a higher mass than expected, (iv) gas mass estimates from X-ray surface brightness profiles may be incorrect, and (v) turbulent motions make an important contribution to the energy balance of a galaxy halo.

30 pages, 14 figures, accepted to ApJ

References in corpus (40)

• Cold streams in early massive hot haloes as the main mode of galaxy formation
• The Circumgalactic Medium
• The COS-Halos Survey: Physical Conditions and Baryonic Mass in the Low-Redshift Circumgalactic Medium
• Moving mesh cosmology: tracing cosmological gas accretion
• Grackle: a Chemistry and Cooling Library for Astrophysics
• Characterizing the Circumgalactic Medium of Nearby Galaxies with HST/COS and HST/STIS Absorption-Line Spectroscopy
• The COS-Dwarfs Survey: The Carbon Reservoir Around sub-L* Galaxies
• Regulation of star formation in giant galaxies by precipitation, feedback, and conduction
• Do Hot Haloes Around Galaxies Contain the Missing Baryons?
• Total mass biases in X-ray galaxy clusters
• The COS-Halos Survey: Origins of the Highly Ionized Circumgalactic Medium of Star-Forming Galaxies
• Hydrodynamic Simulation of Non-thermal Pressure Profiles of Galaxy Clusters
• Properties of the Circumgalactic Medium in Cosmic Ray-Dominated Galaxy Halos
• Multiphase Gas and the Fractal Nature of Radiative Turbulent Mixing Layers
• Virialization of the inner CGM in the FIRE simulations and implications for galaxy discs, star formation and feedback
• Evidence for a Massive, Extended Circumgalactic Medium Around the Andromeda Galaxy
• Cooling flow solutions for the circumgalactic medium
• The Impact of Cosmic Rays on Thermal Instability in the Circumgalactic Medium
• Instability of Supersonic Cold Streams Feeding Galaxies IV: Survival of Radiatively Cooling Streams
• Radiative Mixing Layers: Insights from Turbulent Combustion
• Constraining Gas Motions in the Intra-Cluster Medium
• Kinematics of Circumgalactic Gas: Feeding Galaxies and Feedback
• COS-Burst: Observations of the Impact of Starburst-Driven Winds on the Properties of the Circum-Galactic Medium
• Direct Detection of Black Hole-Driven Turbulence in the Centers of Galaxy Clusters
• Project AMIGA: The Circumgalactic Medium of Andromeda
• Exploring the hydrostatic mass bias in MUSIC clusters: application to the NIKA2 mock sample
• The Properties of the Circumgalactic Medium in Red and Blue Galaxies: Results from the COS-GASS+COS-Halos Surveys
• The Cosmic Ultraviolet Baryon Survey (CUBS) I. Overview and the diverse environments of Lyman limit systems at z<1
• First results from SMAUG: Uncovering the Origin of the Multiphase Circumgalactic Medium with a Comparative Analysis of Idealized and Cosmological Simulations
• Resolving shocks and filaments in galaxy formation simulations: effects on gas properties and star formation in the circumgalactic medium
• How Gas Accretion Feeds Galactic Disks
• How Do Supernovae Impact the Circumgalactic Medium? I. Large-Scale Fountains Around a Milky Way-Like Galaxy
• The COS Absorption Survey of Baryon Harbors: Unveiling the Physical Conditions of Circumgalactic Gas through Multiphase Bayesian Ionization Modeling
• Circumgalactic Oxygen Absorption and Feedback
• Figuring Out Gas & Galaxies In Enzo (FOGGIE). IV. The Stochasticity of Ram Pressure Stripping in Galactic Halos
• Circumgalactic Pressure Profiles Indicate Precipitation-Limited Atmospheres for $M_{\ast }\sim 10^9$$-$$10^{11.5}{M}_{\odot }$
• Figuring Out Gas & Galaxies in Enzo (FOGGIE). III. The Mocky Way: Investigating Biases in Observing the Milky Way's Circumgalactic Medium
• Morphological and Rotation Structures of Circumgalactic Mg II Gas in the EAGLE Simulation and the Dependence on Galaxy Properties
• OVI Traces Photoionized Streams With Collisionally Ionized Boundaries in Cosmological Simulations of $z\sim 1$ Massive Galaxies
• Debiased Galaxy Cluster Pressure Profiles from X-ray Observations and Simulations

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