M. Krumholz. (2013)cite arxiv:1309.5100Comment: 18 pages, 9 figures, accepted for publication in MNRAS.
Abstract
In this paper, I investigate the processes that regulate the rate of star
formation in regions of galaxies where the neutral interstellar medium is
predominantly composed of non-star-forming HI. In such regions, found today
predominantly in low-metallicity dwarf galaxies and in the outer parts of large
spirals, the star formation rate per unit area and per unit mass is much
smaller than in more molecule-rich regions. While in molecule-rich regions the
ultraviolet radiation field produced by efficient star formation forces the
density of the cold neutral medium to a value set by two-phase equilibrium, I
show that the low rates of star formation found in molecule-poor regions
preclude this condition. Instead, the density of the cold neutral gas is set by
the requirements of hydrostatic balance. Using this result, I extend the
Krumholz, McKee, & Tumlinson model for star formation and the atomic to
molecular transition to the molecule-poor regime. This "KMT+" model matches a
wide range of observations of the star formation rate and the balance between
the atomic and molecular phases in dwarfs and in the outer parts of spirals,
and is well-suited to implementation as a subgrid recipe for star formation in
cosmological simulations and semi-analytic models. I discuss the implications
of this model for star formation over cosmological times.
Description
[1309.5100] The Star Formation Law in Molecule-Poor Galaxies
%0 Generic
%1 krumholz2013formation
%A Krumholz, Mark R.
%D 2013
%K atomic gas molecular sfr
%T The Star Formation Law in Molecule-Poor Galaxies
%U http://arxiv.org/abs/1309.5100
%X In this paper, I investigate the processes that regulate the rate of star
formation in regions of galaxies where the neutral interstellar medium is
predominantly composed of non-star-forming HI. In such regions, found today
predominantly in low-metallicity dwarf galaxies and in the outer parts of large
spirals, the star formation rate per unit area and per unit mass is much
smaller than in more molecule-rich regions. While in molecule-rich regions the
ultraviolet radiation field produced by efficient star formation forces the
density of the cold neutral medium to a value set by two-phase equilibrium, I
show that the low rates of star formation found in molecule-poor regions
preclude this condition. Instead, the density of the cold neutral gas is set by
the requirements of hydrostatic balance. Using this result, I extend the
Krumholz, McKee, & Tumlinson model for star formation and the atomic to
molecular transition to the molecule-poor regime. This "KMT+" model matches a
wide range of observations of the star formation rate and the balance between
the atomic and molecular phases in dwarfs and in the outer parts of spirals,
and is well-suited to implementation as a subgrid recipe for star formation in
cosmological simulations and semi-analytic models. I discuss the implications
of this model for star formation over cosmological times.
@misc{krumholz2013formation,
abstract = {In this paper, I investigate the processes that regulate the rate of star
formation in regions of galaxies where the neutral interstellar medium is
predominantly composed of non-star-forming HI. In such regions, found today
predominantly in low-metallicity dwarf galaxies and in the outer parts of large
spirals, the star formation rate per unit area and per unit mass is much
smaller than in more molecule-rich regions. While in molecule-rich regions the
ultraviolet radiation field produced by efficient star formation forces the
density of the cold neutral medium to a value set by two-phase equilibrium, I
show that the low rates of star formation found in molecule-poor regions
preclude this condition. Instead, the density of the cold neutral gas is set by
the requirements of hydrostatic balance. Using this result, I extend the
Krumholz, McKee, & Tumlinson model for star formation and the atomic to
molecular transition to the molecule-poor regime. This "KMT+" model matches a
wide range of observations of the star formation rate and the balance between
the atomic and molecular phases in dwarfs and in the outer parts of spirals,
and is well-suited to implementation as a subgrid recipe for star formation in
cosmological simulations and semi-analytic models. I discuss the implications
of this model for star formation over cosmological times.},
added-at = {2013-09-23T16:45:18.000+0200},
author = {Krumholz, Mark R.},
biburl = {https://www.bibsonomy.org/bibtex/28ded6e1db41af6c3e1b54fa38cd35852/miki},
description = {[1309.5100] The Star Formation Law in Molecule-Poor Galaxies},
interhash = {55e31d1b5c9b2a8d5b089f36e530013e},
intrahash = {8ded6e1db41af6c3e1b54fa38cd35852},
keywords = {atomic gas molecular sfr},
note = {cite arxiv:1309.5100Comment: 18 pages, 9 figures, accepted for publication in MNRAS},
timestamp = {2013-09-23T16:45:18.000+0200},
title = {The Star Formation Law in Molecule-Poor Galaxies},
url = {http://arxiv.org/abs/1309.5100},
year = 2013
}