Reignited star formation in dwarf galaxies quenched during reionization

Understand

Irregular dwarf galaxies of the Local Group have very varied properties and star formation histories.

• Some of them formed the majority of their stars very late compared to the others.
• Extreme examples are Leo A and Aquarius which reached the peak of star formation at $z<1$ ( > 6 Gyr after BB).
• This fact seemingly challenges the LCDM cosmology because the dark matter halos of these galaxies on average should assemble the majority of their masses before z~2 (<3 Gyr after BB).