Tuesday

Dwarf galaxies are the most common type of galaxies in the Universe at all epochs and they play a fundamental role in cosmic history, being responsible for the build up of massive galaxies and possibly driving the reionization and metal enrichment processes. High-redshift observations of such sources are not available yet, but we demonstrate that the James Webb Space Telescope (JWST) will catch for the first time the light of the faint satellite dwarf galaxies orbiting around massive Lyman Break Galaxies (LBGs).
We use state-of-art cosmological simulations of a typical LBG at z=6 to uncover the properties of satellite galaxies and make predictions for the upcoming JWST observations. These dwarf galaxies cover a wide range of stellar masses (log(M⋆/M⊙)≃7−9). We find that, even in such extremely dense environments, internal supernovae feedback is the key mechanism regulating their evolution, capable of completely quenching dwarf galaxies. Only the frequent merger events characterising these biased regions can effectively prolong the star-formation in the most massive satellites.
Modelling their stellar emission and dust attenuation, we reconstruct their spectral energy distributions and produce JWST/NIRCam mock images. These reveal how the instrument’s high resolution will allow us to spatially resolve these small systems from the nearby host. Color-magnitude diagrams will be a powerful diagnostic tool to infer their properties: it will be possible, for instance, to identify star-bursting, young and metal-poor satellites. Thanks JWST’s high sensitivities, already within planned deep surveys we will detect, for the first time and for free, the faint satellite dwarf galaxies of high-z LBGs.