Quantifying Supernovae-driven Multiphase Galactic Outflows

Galactic outflows are observed everywhere in star-forming disk galaxies and are critical for galaxy formation. Supernovae (SNe) play the key role in driving the outflows, but there is no consensus as to how much energy, mass, and metal they can launch out of the disk. We perform 3D, high-resolution...

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Bibliographic Details
Published in:The Astrophysical journal 2017-06, Vol.841 (2), p.101
Main Authors: Li, Miao, Bryan, Greg L., Ostriker, Jeremiah P.
Format: Article
Language:English
Subjects:
Astrophysics
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
COMPUTERIZED SIMULATION
DENSITY
Disk galaxies
DISTRIBUTION
EFFICIENCY
GALACTIC EVOLUTION
GALAXIES
galaxies: formation
galaxies: ISM
GRAVITATIONAL FIELDS
HYDRODYNAMICS
ISM: kinematics and dynamics
ISM: structure
MASS
METALS
Outflow
Photoelectricity
RESOLUTION
Scale height
Star & galaxy formation
Star formation
SUPERNOVAE
SURFACES
Vertical distribution
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Summary:Galactic outflows are observed everywhere in star-forming disk galaxies and are critical for galaxy formation. Supernovae (SNe) play the key role in driving the outflows, but there is no consensus as to how much energy, mass, and metal they can launch out of the disk. We perform 3D, high-resolution hydrodynamic simulations to study SNe-driven outflows from stratified media. Assuming the SN rate scales with gas surface density gas as in the Kennicutt-Schmidt relation, we find that the mass loading factor, m, defined as the mass outflow flux divided by the star formation surface density, decreases with increasing gas as . Approximately gas 50 M pc−2 marks when m 1. About 10%-50% of the energy and 40%-80% of the metals produced by SNe end up in the outflows. The tenuous hot phase (T > 3 × 105 K), which fills 60%-80% of the volume at the midplane, carries the majority of the energy and metals in the outflows. We discuss how various physical processes, including the vertical distribution of SNe, photoelectric heating, external gravitational field, and SN rate, affect the loading efficiencies. The relative scale height of gas and SNe is a very important factor in determining the loading efficiencies.
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/aa7263