| Description |
We propose a spectroscopic survey of the Small Magellanic Cloud (SMC)
designed to measure the impact of metallicity on the interstellar
medium and specifically to determine the mass and structure of
molecular gas residing in a CO-dark phase. The SMC is the nearest
truly low-metallicity, actively star-forming galaxy and shows the best
evidence of any galaxy of being dominated by CO-dark H2 gas. This
makes the SMC an absolutely unique target and the best source to study
how the H2 reservoir, the relation between star formation and H2, and
the relation between H2 and CO are affected by metallicity. These are
key problems with far-reaching implications for the evolution of the
star formation across cosmic time and the interpretation of
high-redshift observations in the ALMA era. Our survey consists
spectral mapping with FTS+PACS ([CII], [OI], [NII], [OIII]) of 5
regions selected to span a wide range in r^ant parameter space and
enable a clean and precise measurement of the abundance of CO-dark
molecular gas. This rich dataset will have lasting legacy value and
address a key gap in the Herschel legacy, enabling studies in a wide
range of other topics. Moreover, the coIs will publicly distribute the
data products 18 months after the end of observations. The team have
extensive leading expertise on these science topics, as well as
modeling and data reduction. |
