Why can dwarf irregular galaxies often sustain star formation for longer periods than giant spirals?

Answer

They are less centrally concentrated and can retain gas longer

Irregular galaxies, especially smaller dwarf irregulars, are less massive and less centrally concentrated, allowing them to retain their gas supply more effectively, promoting sustained or sporadic star formation over extended periods compared to massive systems.

Why can dwarf irregular galaxies often sustain star formation for longer periods than giant spirals?
galaxiesastronomystarsstellar evolutiongalaxy types