Magnetized gas clouds can survive acceleration by a hot wind
By Michael McCourt, Ryan M. O’Leary, A. Madigan, E. Quataert. 2014
163 citations recorded by the source corpus.
We present three-dimensional magnetohydrodynamic simulations of magnetized gas clouds accelerated by hot winds. We initialize gas clouds with tangled internal magnetic fields and show that this field suppresses the disruption of the cloud: rather than mixing into the hot wind as found in hydrodynamic simulations, cloud fragments end up co-moving and in pressure equilibrium with their surroundings. We also show that a magnetic field in the hot wind enhances the drag force on the cloud by a factor ~(1+v_A^2/v_wind^2)$, where v_A is the Alfven speed in the wind and v_wind measures the relative speed between the cloud and the wind. We apply this result to gas clouds in several astrophysical contexts, including galaxy clusters, galactic winds, the Galactic center, and the outskirts of the Galactic halo. Our results can explain the prevalence of cool gas in galactic winds and galactic halos and how such cool gas survives in spite of its interaction with hot wind/halo gas. We also predict that drag forces can lead to a deviation from Keplerian orbits for the G2 cloud in the galactic center.
Subfields: Astronomy and Astrophysics
View Paper: https://www.semanticscholar.org/paper/7a793d2810bee798cf6a6a9cc821e8a9101f721d
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In Astronomy and Astrophysics
Citations in the corpus
- Supernova feedback in an inhomogeneous interstellar medium (2014, background): “A more significant uncertainty may be that magnetic fields can alter the mixing of cool and hot gas by suppressing Kelvin–Helmholtz and related instabilities, thus modifying the cloud mixing process (e.g. Shin, Stone & Snyder 2008; McCourt et al. 2015).”
- An origin for multiphase gas in galactic winds and haloes (2015, background): “…gas clouds are accelerated to the velocities and large scales seen without being shredded by hydrodynamical instabilities and incorporated into the hot flow (Klein et al. 1994; Cooper et al. 2009; Marcolini et al. 2005; McCourt et al. 2015; Scannapieco & Brüggen 2015; Schneider & Robertson 2014).”
- A characteristic scale for cold gas (2016, methodology): “Some studies have identified mechanisms to delay the disruption of gas clouds, possibly enabling entrainment over a range of parameters (e. g. Cooper et al., 2009; McCourt et al., 2015).”
- The impact of star formation feedback on the circumgalactic medium (2016, background): “Magnetic fields, anisotropic conduction, and cosmic rays may also play an important role in the evolution and phase structure of the CGM (e.g., Booth et al. 2013; McCourt et al. 2015).”
- AGN outflows and feedback twenty years on (2018, unknown): “It is mostly thought to be associated with gas which is entrained by a hotter wind[81], pushed directly through radiation pressure[82] or gas that cools within the outflow”
- The growth and entrainment of cold gas in a hot wind (2018, methodology): “…parameters relevant for a range of astrophysical systems, and initialize the setup in pressure equilibrium with the initial cloud’s temperature to be Tcl ≈ 4× 104 K.1 As in McCourt et al. (2015) we use a cloud-tracking scheme which changes the reference frame continuously to follow the cold gas.”