Molecular Cloud Properties and CO Line Emission in z >~ 6 Galaxies
J. Muñoz, and S. Furlanetto. (2013)cite arxiv:1301.0619Comment: 18 pages, 11 figures; submitted to MNRAS; comments welcome.
Abstract
We explore molecular cloud properties and the physics of CO transition lines
in z >~ 6 Lyman-break galaxies and predict their CO fluxes using an analytic
formalism built from global models of star formation in high-redshift galaxies
that minimizes our reliance on local observations. Our model includes a new
approach to calculating the molecular gas fraction that takes the total gas
density, the star formation rate, and the star formation efficiency in clouds
as the principle inputs. This method agrees with chemical equilibrium
calculations of the molecular fraction based on local chemistry if galaxies at
z >~ 6 have metallicities in the range of 3--30 percent of solar. Such low
metallicities in turn imply that much of the carbon in these systems exists in
ionized form rather than as CO. Moreover, we find that CO transitions will
typically be sub-thermally populated, especially those higher-order lines
observable at high redshift with ALMA. Ultimately, we expect current facilities
will not be able to observe the CO signal from reionization epoch galaxies
except with great difficulty. We estimate that ~1000 hours of integration with
JVLA will be required to detect the CO(1--0) transition in even the most
UV-bright systems at z = 6.
Description
[1301.0619] Molecular Cloud Properties and CO Line Emission in z >~ 6 Galaxies
%0 Generic
%1 munoz2013molecular
%A Muñoz, Joseph A.
%A Furlanetto, Steven R.
%D 2013
%K gas high-z molecular
%T Molecular Cloud Properties and CO Line Emission in z >~ 6 Galaxies
%U http://arxiv.org/abs/1301.0619
%X We explore molecular cloud properties and the physics of CO transition lines
in z >~ 6 Lyman-break galaxies and predict their CO fluxes using an analytic
formalism built from global models of star formation in high-redshift galaxies
that minimizes our reliance on local observations. Our model includes a new
approach to calculating the molecular gas fraction that takes the total gas
density, the star formation rate, and the star formation efficiency in clouds
as the principle inputs. This method agrees with chemical equilibrium
calculations of the molecular fraction based on local chemistry if galaxies at
z >~ 6 have metallicities in the range of 3--30 percent of solar. Such low
metallicities in turn imply that much of the carbon in these systems exists in
ionized form rather than as CO. Moreover, we find that CO transitions will
typically be sub-thermally populated, especially those higher-order lines
observable at high redshift with ALMA. Ultimately, we expect current facilities
will not be able to observe the CO signal from reionization epoch galaxies
except with great difficulty. We estimate that ~1000 hours of integration with
JVLA will be required to detect the CO(1--0) transition in even the most
UV-bright systems at z = 6.
@misc{munoz2013molecular,
abstract = {We explore molecular cloud properties and the physics of CO transition lines
in z >~ 6 Lyman-break galaxies and predict their CO fluxes using an analytic
formalism built from global models of star formation in high-redshift galaxies
that minimizes our reliance on local observations. Our model includes a new
approach to calculating the molecular gas fraction that takes the total gas
density, the star formation rate, and the star formation efficiency in clouds
as the principle inputs. This method agrees with chemical equilibrium
calculations of the molecular fraction based on local chemistry if galaxies at
z >~ 6 have metallicities in the range of 3--30 percent of solar. Such low
metallicities in turn imply that much of the carbon in these systems exists in
ionized form rather than as CO. Moreover, we find that CO transitions will
typically be sub-thermally populated, especially those higher-order lines
observable at high redshift with ALMA. Ultimately, we expect current facilities
will not be able to observe the CO signal from reionization epoch galaxies
except with great difficulty. We estimate that ~1000 hours of integration with
JVLA will be required to detect the CO(1--0) transition in even the most
UV-bright systems at z = 6.},
added-at = {2013-01-08T15:52:43.000+0100},
author = {Muñoz, Joseph A. and Furlanetto, Steven R.},
biburl = {https://www.bibsonomy.org/bibtex/2994db51de036e20b73946003576d878d/miki},
description = {[1301.0619] Molecular Cloud Properties and CO Line Emission in z >~ 6 Galaxies},
interhash = {e552b86584b204a371af935d3af9f843},
intrahash = {994db51de036e20b73946003576d878d},
keywords = {gas high-z molecular},
note = {cite arxiv:1301.0619Comment: 18 pages, 11 figures; submitted to MNRAS; comments welcome},
timestamp = {2013-01-08T15:52:43.000+0100},
title = {Molecular Cloud Properties and CO Line Emission in z >~ 6 Galaxies},
url = {http://arxiv.org/abs/1301.0619},
year = 2013
}