Role of cosmic rays in the early stages of galactic outflows

Abstract

Using an idealized set-up, we investigate the dynamical role of cosmic rays (CRs) in the early stages of galactic outflows for galaxies of halo masses $10^8$, $10^{11}$ and $10^{12}$ $M_{\odot }$. The outflow is launched from a central region in the galactic disk where we consider three different constant star formation rates ($0.1$, $1$, and $10$ $M_{\odot }$ yr${}^{-1}$) over a dynamical timescale of $50$ Myr. We determine the temperature distribution of the gas and find that CRs can reduce the temperature of the shocked gas, which is consistent with previous results. However, we show that CRs do not have any noticeable effect on the mass loading by the outflow. We find that CRs can reduce the size of the outflow, which contradicts previous claims of efficient dynamical impact of CRs; however, it is consistent with earlier theoretical models of cosmic ray driven blastwave as well as stellar wind. We discuss the dependence of our results on CR injection prescriptions and compare them with earlier studies. We conclude that in the early stages of galactic outflows the dynamical role of CRs is not important.

19 pages, 2 tables, 19 figures, accepted for publication in MNRAS, Link to time evolution of the simulation performed : https://youtu.be/3-JZAv7vwo8

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Cited by in corpus (10)

• The Structure of Multiphase Galactic Winds
• The Impact of Cosmic Rays on Thermal Instability in the Circumgalactic Medium
• Radiation-MagnetoHydrodynamics simulations of cosmic ray feedback in disc galaxies
• The Launching of Cold Clouds by Galaxy Outflows. IV. Cosmic-Ray-Driven Acceleration
• Dynamical Effects of Cosmic Rays on the Medium Surrounding Their Sources
• Cosmic-ray generated bubbles around their sources
• The Impact of Cosmic Rays on the Kinematics of the Circumgalactic Medium
• The phase structure of cosmic ray driven outflows in stream fed disc galaxies
• Dust in Clusters of Galaxies
• Radio Halo of NGC 4631: Comparing Observations and Simulations