  Luminous compact blue galaxies (LCBGs) have enhanced star formation rates and
compact morphologies. We combine Sloan Digital Sky Survey data with HI data of
29 LCBGs at redshift z~0 to understand their nature. We find that local LCBGs
have high atomic gas fractions (~50%) and star formation rates per stellar mass
consistent with some high redshift star forming galaxies. Many local LCBGs also
have clumpy morphologies, with clumps distributed across their disks. Although
rare, these galaxies appear to be similar to the clumpy star forming galaxies
commonly observed at z~1-3. Local LCBGs separate into three groups: 1.
Interacting galaxies (~20%); 2. Clumpy spirals (~40%); 3. Non-clumpy,
non-spirals with regular shapes and smaller effective radii and stellar masses
(~40%). It seems that the method of building up a high gas fraction, which then
triggers star formation, is not the same for all local LCBGs. This may lead to
a dichotomy in galaxy characteristics. We consider possible gas delivery
scenarios and suggest that clumpy spirals, preferentially located in clusters
and with companions, are smoothly accreting gas from tidally disrupted
companions and/or intracluster gas enriched by stripped satellites. Conversely,
as non-clumpy galaxies are preferentially located in the field and tend to be
isolated, we suggest clumpy, cold streams, which destroy galaxy disks and
prevent clump formation, as a likely gas delivery mechanism for these systems.
Other possibilities include smooth cold streams, a series of minor mergers, or
major interactions.
