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2012MNRAS.421.3488H - Mon. Not. R. Astron. Soc., 421, 3488-3521 (2012/April-3)
The structure of the interstellar medium of star-forming galaxies.
HOPKINS P.F., QUATAERT E. and MURRAY N.
Abstract (from CDS):
Our primary results on the structure of the ISM in star-forming galaxies include the following.
{\listitem {\label 1} {\par}Star-forming galaxies generically self-regulate so that the cool, dense gas maintains Toomre's {\em Q} ~ 1. Most of the volume is occupied by relatively diffuse hot gas, while most of the mass is in dense GMC complexes created by self-gravity. The phase structure of the gas and the gas mass fraction at high densities are much more sensitive probes of the physics of stellar feedback than integrated quantities such as the Toomre {\em Q} or gas velocity dispersion.} {\listitem {\label 2} {\par}Different stellar feedback mechanisms act on different spatial (and density) scales. Radiation pressure and H {\sc ii} gas pressure are critical for preventing runaway collapse of dense gas in GMCs. Shocked supernova ejecta and stellar winds dominate the dynamics of the volume-filling hot gas. However, this gas primarily vents out of the star-forming disc and contributes only modestly to the mid-plane ISM pressure.} {\listitem {\label 3} {\par}The galaxy-averaged star formation rate is determined by feedback, with different mechanisms dominating in different galaxy types. For a given feedback efficiency, restricting star formation to molecular gas or modifying the cooling function has little effect on the star formation rate in the galaxies we model (including an SMC-mass dwarf). By contrast, changing the feedback mechanisms or assumed feedback efficiencies directly translates to shifts off of the observed Kennicutt--Schmidt relation.} {\listitem {\label 4} {\par}Self-gravity leads to GMCs with an approximately self-similar mass function {prop.to}{\em M}^-2^, with a high-mass cut-off determined by the characteristic Jeans/Toomre mass of the system. In all of our galaxy models, GMCs live for a few dynamical times before they are disrupted by stellar feedback. The net star formation efficiency in GMCs ranges from ~ 1 per cent in dwarfs and MW-like spirals to nearly ~ 10 per cent in gas-rich rapidly star-forming galaxies. GMCs are approximately virialized, but there is a large dispersion in the virial parameter for a given GMC mass, and lower mass GMCs tend to be preferentially unbound.}
Abstract Copyright: 2012 The Author Monthly Notices of the Royal Astronomical Society2012 RAS
Journal keyword(s): stars: formation - galaxies: active - galaxies: evolution - galaxies: formation - cosmology: theory
Simbad objects: 7
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