TiNy Titans: The Role of Dwarf-Dwarf Interactions in the Evolution of
  Low Mass Galaxies
  We introduce TiNy Titans (TNT), the first systematic study of star formation
and the subsequent processing of the interstellar medium in interacting dwarf
galaxies. Here we present the first results from a multiwavelength
observational program based on a sample of 104 dwarf galaxy pairs selected from
a range of environments within the SDSS and caught in various stages of
interaction. The TNT dwarf pairs span mass ratios of M1/M2 <10, projected
separations <50 kpc, and pair member masses of 7< log(M_*/Msun) <9.7. The
dwarf-dwarf merger sequence, as defined by TNT, demonstrates conclusively and
for the first time that the star formation enhancement observed for massive
galaxy pairs also extends to dwarfs. Star formation is enhanced in paired
dwarfs in otherwise isolated environments by a factor of 2.3 (+/- 0.7) at pair
separations < 50 kpc relative to unpaired analogs. Starbursts, with Ha EQW >100
A, occur in 20% of TNT dwarf pairs, regardless of environment, compared to only
6-8% of matched unpaired dwarfs. Starbursts can be triggered throughout the
merger (out to large pair separations) and not just approaching coalescence.
Despite their enhanced star formation, most TNT dwarf pairs have similar gas
fractions relative to unpaired dwarfs. Thus, there may be significant
reservoirs of diffuse, non-starforming gas surrounding the dwarf pairs or the
gas consumption timescales may be long in the starburst phase. The only TNT
dwarf pairs with low gas fractions (fgas <0.4) and the only dwarfs with Ha EQW
<2 A are found near massive galaxy hosts. Thus, dwarf-dwarf interactions are
significant drivers of dwarf galaxy evolution, but ultimately environment is
responsible for the quenching of star formation. This work is a precursor to an
ongoing high resolution HI and optical imaging program to constrain the spatial
distribution of star formation and gas throughout the dwarf-dwarf merger
sequence.
