  We investigate the assumption that the trigger of star formation in dwarf
galaxies are interactions with other galaxies, in the context of a search for a
"primary" trigger of a first generation of stars. This is cosmologically
relevant because the galaxy formation process consists not only of the
accumulation of gas in a gravitational potential well, but also of the
triggering of star formation in this gas mass and also because some high-z
potentially primeval galaxy blocks look like nearby star-forming dwarf
galaxies. We review theoretical ideas proposed to account for the tidal
interaction triggering mechanism and present a series of observational tests of
this assumption using published data. We show also results of a search in the
vicinity of a composite sample of 96 dwarf late-type galaxies for interaction
candidates showing star formation. The small number of possible perturbing
galaxies indentified in the neighborhood of our sample galaxies, along with
similar findings from other studies, supports the view that tidal interactions
may not be relevant as primary triggers of star formation. We conclude that
interactions between galaxies may explain some forms of star formation
triggering, perhaps in central regions of large galaxies, but they do not seem
to be significant for dwarf galaxies and, by inference, for first-time galaxies
forming at high redshifts. Intuitive reasoning, based on an analogy with
stellar dynamics, shows that conditions for primary star formation triggering
may occur in gas masses oscillating in a dark matter potential. We propose this
mechanism as a plausible primary trigger scenario, worth investigating
theoretically.
