| Description |
Molecular gas is difficult to detect from traditional millimeter CO transitions
in dwarf galaxies below a certain metallicity. Yet, there is evidence for lots of
molecular H_2 in these galaxies. Fortunately, Photo-dissociation Regions are a
better tracer of the molecular material in low metallicity systems. In metal-poor
galaxies, PDRs dominate the molecular core where CO is found, and in the
current paradigm the PDR grows and the core shrinks as metallicity decreases.
Thus, we expect critical differences in the molecular clouds of dwarfs compared
to spirals, with the differences becoming more extreme with lower metallicity.
Yet, understanding these differences and their consequences to star formation
is essential to understanding the processes that drive star formation at low
metallicities. Therefore, we propose to observe the PDRs in 5 regions in 5
typical metal-poor dwarf galaxies spanning a range in oxygen abundance. We
will use these observations to characterize the molecular gas, examine the
correspondence between the molecular clouds and the atomic gas and star
formation characteristics, and determine the characteristics of the atomic
ISM that are necessary for the formation of these dense molecular clouds.
We will also test the molecular cloud structure paradigm as a function of
metallicity. |
