The role of cosmic-ray pressure in accelerating galactic outflows

Simpson, Christine M., Pakmor, Rüdiger, Marinacci, Federico, Pfrommer, Christoph, Springel, Volker, Glover, Simon C. O., Clark, Paul ORCID: https://orcid.org/0000-0002-4834-043X and Smith, Rowan J. 2017. The role of cosmic-ray pressure in accelerating galactic outflows. The Astrophysical Journal 827 (2) , L29. 10.3847/2041-8205/827/2/L29

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Abstract

We study the formation of galactic outflows from supernova (SN) explosions with the moving-mesh code AREPO in a stratified column of gas with a surface density similar to the Milky Way disk at the solar circle. We compare different simulation models for SN placement and energy feedback, including cosmic rays (CRs), and find that models that place SNe in dense gas and account for CR diffusion are able to drive outflows with similar mass loading as obtained from a random placement of SNe with no CRs. Despite this similarity, CR-driven outflows differ in several other key properties including their overall clumpiness and velocity. Moreover, the forces driving these outflows originate in different sources of pressure, with the CR diffusion model relying on non-thermal pressure gradients to create an outflow driven by internal pressure and the random-placement model depending on kinetic pressure gradients to propel a ballistic outflow. CRs therefore appear to be non-negligible physics in the formation of outflows from the interstellar medium.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Physics and Astronomy
Subjects:	Q Science > QB Astronomy
Publisher:	IOP Sciences
ISSN:	2041-8213
Date of First Compliant Deposit:	7 July 2017
Date of Acceptance:	26 July 2016
Last Modified:	05 May 2023 10:06
URI:	https://orca.cardiff.ac.uk/id/eprint/102168

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