Despite their small sizes and masses, dwarf galaxies are key protagonists of cosmic history: they are the first galaxies to form in the Universe, the most numerous at all times and the building blocks of massive galaxies like our own Milky Way. They have been thoroughly observed in the Local Universe, but their properties at cosmic dawn, during the first billion years after the Big Bang, are still unexplored. Soon, however, the groundbreaking James
Webb Space Telescope (launch in 2021) will target massive Lyman Break Galaxies at very high redshifts (z>6) and catch for the first time the light of the faint satellite dwarf galaxies orbiting around them. What are their expected key properties? Are they influenced by the nearby massive galaxy? Are they affected by feedback effects? We investigate these questions using a state-of-art cosmological simulation of a typical massive Lyman Break Galaxies at z=6, and unveiling the properties of its satellite dwarf galaxies. We find that, even in such extremely dense environments, internal supernovae feedback is the key mechanism regulating their evolution and leading to their quenching. The frequent merger events characterizing these biased regions can however effectively prolong the star-formation in the most massive satellites. Moreover, all of these small galaxies form their stars at surprisingly high star formation rates, ensuring that JWST will indeed be able to detect them.
Gelli, Salvadori, Pallottini, and Ferrara 2020, MNRAS, 498, 3