 Several fundamental questions about the inner part of our Galaxy, the Bulge, are still without answer because this region is dense and with high extinction so that present telescopes can catch only the few brightest stars there. With MOSAIC we will be able to observe unevolved stars, the largest population in the bulge. In particular, for the first time, we will be able to observe in the Bulge stars that, as our Sun, are sill on the Main Sequence. This stellar population will reveal us the kinematic and metallicity of the Bulge, and, hosting the large majority of the stars, will allow us to better estimate the mass of our Galaxy. With a good knowledge on the complete sequence of the stellar evolution in the Bulge, we will derive also stellar ages. We will then have the possibility to draw a picture on the formation and past history of our Galaxy and to understand its actual shape. | ||
 Lithium is the heaviest nucleus produced in the Big Bang Nucleosynthesis (BBN). The other sources of Li production operate on long time-scales (> than 2 Gyr) so that lithium observed in the old stars must come from the BBN. The lithium abundance measured in the stellar atmospheres is almost the same for all the old unevolved stars but it is one third of the standard BBN prediction. Is this a sign of "new physics", beyond the standard model? Has lithium been uniformly destroyed in all the stars? All the theories predicting lithium destruction fail to explain at the same time the homogeneity and such a large destruction. Is this behaviour unique to our Galaxy? Only with MOSAIC we will be able to observed for the first time, lithium in several external galaxies and answer this question. | ||
 MOSAIC on ELT will carry out the first statistically significant survey of the chemo-dynamical properties of dwarf galaxies at 1 < z < 3, when the Universe was less than half its current age. The unrivalled visual acuity, sensitivity and multiplexity of the spectrograph will allow the study of spatially-resolved chemical inhomogeneities in large samples of high-z dwarfs. Their chemical maps, further complemented with detailed kinematic information of the ionised gas across the galaxy shall uncover the presence of infall-driven, turbulent star formation, as well as reveal the imprints of energetic outflows from supernovae. The dwarf irregular galaxy IC1613 Credit: NASA/JPL-Caltech/SSC | ||
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MOSAIC will characterise gaseous outflows in large samples of active galactic nuclei (AGN) over cosmic time and with a wide range of luminosities. The unique spectroscopic capabilities of the instrument, further enhanced by adaptive optics corrections, will allow us to map in detail the outflows of ionised and neutral gas, including their kinetic energies and mass outflow rates, and to constrain their extent and geometries. Such a comprehensive census will finally provide a self-consistent picture of the impact of SMBH-driven outflows on the regulation of star formation in galaxies.
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MOSAIC will detect and study the very first galaxies. Their light, which has taken more than 13 billion years to reach us, will provide us with vital clues to our understanding of the early epoch when the Universe was ‘reionised’, during which its gas changed from a universally neutral into an ionised state.
 The warm and hot gas between galaxies and within their halo is a reservoir of matter from which proto-galaxies can form. MOSAIC will provide an unprecedented map of the distant 3D structures of this gas as well as evaluating for the first time the distribution of the different baryonic components of the matter. | ||
