CR Driven Multi-phase Gas Formed via Thermal Instability

Abstract

Cosmic rays (CRs) are an important energy source in the circum-galactic medium (CGM) that impact the multi-phase gas structure and dynamics. We perform two-dimensional CR-magnetohydrodynamic simulations to investigate the role of CRs in accelerating multi-phase gas formed via thermal instability. We compare outflows driven by CRs to those driven by a hot wind with equivalent momentum. We find that CRs driven outflow produces lower density contrast between cold and hot gas due to non-thermal pressure support, and yields a more filamentary cloud morphology. While entrainment in a hot wind can lead to cold gas increasing due to efficient cooling, CRs tend to suppress cold gas growth. The mechanism of this suppression depends on magnetic field strength, with CRs either reducing cooling or shredding the clouds by differential acceleration. Despite the suppression of cold gas growth, CRs are able to launch the cold clouds to observed velocities without rapid destruction. The dynamical interaction between CRs ad multi-phase gas is also sensitive to the magnetic field strength. In relatively strong fields, the CRs are more important for direct momentum input to cold gas. In relatively weak fields, the CRs impact gas primarily by heating, which modifies gas pressure.

22 pages, 18 figures

References in corpus (9)

• scikit-image: Image processing in Python
• The Circumgalactic Medium
• The COS-Halos Survey: Physical Conditions and Baryonic Mass in the Low-Redshift Circumgalactic Medium
• Magnetized Gas Clouds can Survive Acceleration by a Hot Wind
• The Launching of Cold Clouds by Galaxy Outflows I: Hydrodynamic Interactions with Radiative Cooling
• Cosmic ray-driven galactic winds: streaming or diffusion?
• Multiphase gas in the circumgalactic medium: relative role of $t_{\mathrm{cool}}/t_{\mathrm{ff}}$ and density fluctuations
• NOEMA High Fidelity Imaging of the Molecular Gas in and around M82
• Comparing different closure relations for cosmic ray hydrodynamics

Cited by in corpus (10)

• The Circumgalactic Medium of Milky Way-like Galaxies in the TNG50 Simulation -- I: Halo Gas Properties and the Role of SMBH Feedback
• Cloudy with A Chance of Rain: Accretion Braking of Cold Clouds
• Cosmic rays and thermal instability in self-regulating cooling flows of massive galaxy clusters
• Turbulent Reacceleration of Streaming Cosmic Rays
• Cosmic-Ray Driven Galactic Winds from the Warm Interstellar Medium
• Observational Constraints on Cool Gas Clouds in M82's Starburst-Driven Outflow
• XMAGNET: Velocity structure functions of active galactic nucleus-driven turbulence in the multiphase intracluster medium
• Cold fronts in galaxy clusters I: A case for the large-scale global eigen modes in unmagnetized and weakly magnetized cluster core
• Multi-cloud crushing -- the collective survival of cold clouds in galactic outflows
• Neural Infalling Cloud Equations (NICE): Increasing the Efficacy of Subgrid Models and Scientific Equation Discovery using Neural ODEs and Symbolic Regression