The Impact of Cosmic Ray Injection on Magnetic Flux Tubes in a Galactic Disk
Roark Habegger, Ellen G. Zweibel, Sherry Wong

TL;DR
This study investigates how localized cosmic ray injections influence magnetic flux tubes and the interstellar medium in galactic disks, revealing that injection effects vary significantly with the dominant cosmic ray transport mechanism.
Contribution
The paper introduces the first large-scale cosmic ray magnetohydrodynamic simulations examining the impact of localized cosmic ray injection on galactic disk stability.
Findings
Injection disrupts the interstellar medium faster than Parker instability.
Transport by advection leads to rapid disruption (<100 Myr).
Transport by diffusion causes overpressure and buoyant rise of flux tubes.
Abstract
In galactic disks, the Parker instability results when non-thermal pressure support exceeds a certain threshold. The non-thermal pressures considered in the Parker instability are cosmic ray pressure and magnetic pressure. This instability takes a long time to saturate and assumes a background with fixed cosmic ray pressure to gas pressure ratio. In reality, galactic cosmic rays are injected into localized regions by events like supernovae, increasing the cosmic ray pressure to gas pressure ratio. In this work, we examine the effect of such cosmic ray injection on large scales in cosmic ray magnetohydrodynamic simulations using the \texttt{Athena++} code. We vary the background properties, dominant cosmic ray transport mechanism, and injection characteristics between our simulation runs. We find the injection…
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Taxonomy
TopicsAstrophysics and Star Formation Studies · Solar and Space Plasma Dynamics · Gamma-ray bursts and supernovae
