An Overview of the Dwarf Galaxy Survey
  The Dwarf Galaxy Survey (DGS) program is studying low-metallicity galaxies
using 230h of far-infrared (FIR) and submillimetre (submm) photometric and
spectroscopic observations of the Herschel Space Observatory and draws to this
a rich database of a wide range of wavelengths tracing the dust, gas and stars.
This sample of 50 galaxies includes the largest metallicity range achievable in
the local Universe including the lowest metallicity (Z) galaxies, 1/50 Zsun,
and spans 4 orders of magnitude in star formation rates. The survey is designed
to get a handle on the physics of the interstellar medium (ISM) of low
metallicity dwarf galaxies, especially on their dust and gas properties and the
ISM heating and cooling processes. The DGS produces PACS and SPIRE maps of
low-metallicity galaxies observed at 70, 100, 160, 250, 350, and 500 mic with
the highest sensitivity achievable to date in the FIR and submm. The FIR
fine-structure lines, [CII] 158 mic, [OI] 63 mic, [OI] 145 mic, [OIII] 88 mic,
[NIII] 57 mic and [NII] 122 and 205 mic have also been observed with the aim of
studying the gas cooling in the neutral and ionized phases. The SPIRE FTS
observations include many CO lines (J=4-3 to J=13-12), [NII] 205 mic and [CI]
lines at 370 and 609 mic. This paper describes the sample selection and global
properties of the galaxies, the observing strategy as well as the vast
ancillary database available to complement the Herschel observations. The
scientific potential of the full DGS survey is described with some example
results included.
