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The Intergalactic Medium as a Cosmological Tool

Final Report Summary - COSMOIGM (The Intergalactic Medium as a Cosmological Tool)

The cosmoIGM team has investigated the role of matter between galaxies (the Intergalactic medium - IGM) as a cosmological tracer of the underlying large scale structure and as a probe of fundamental physics. Usually, matter between galaxies does not shine, it is a diffuse low density medium which contains gaseous material and dark matter. The IGM can be effectively described has a network of filaments, the so-called cosmic web, at the intersection of which we do find the galaxies like our own. The cosmic web is thus sensitive to the overall dynamical state and geometry of our Universe at unique cosmic epochs, that are poorly probed by other cosmological observable.
The IGM can be studied using the light emitted by distance sources (quasars) and by carefully analyzing the cosmic journey of the photons traveling through the intergalactic medium and reaching the telescopes. On the theoretical side, time consuming super computer simulations of the Universe are made in order to compare data with a given model. The team has placed important constraints on the behavior of dark matter at small scales and on the total mass of neutrino particles in the Universe: to date these are the tightest constraints that cosmology could offer and are of course of fundamental importance for particle physics experiments. The team has also made a comprehensive analysis of data at low, high and medium resolution and constrained physical and chemical properties of the IGM and the intimate relation that exists between the IGM and the galaxies.
Not only the IGM could be considered as a reservoir of the cosmic gas that feeds galaxies and their star formation processes but it is also a sink of the baryons that are expelled by galaxies through their energetic winds. Great efforts have also been made in order to explore new ways of constraining fundamental properties of the Universe like cross-correlating information coming from different cosmic tracers or a full characterization of the neutral hydrogen content at different cosmic epochs using both absorption and emission mechanisms.
The intergalactic medium is a powerful and new cosmological tool that can address fundamental physical questions and aspects related to the formation of galaxies. The cosmoIGM team was composed by 5 members of different nationalities: the PI, Prof. Matteo Viel from Italy; Dr. Barai from India; Dr. Villaescusa-Navarro from Spain; Dr. Enea Di Dio from Switzerland; Dr. Tae-Sun Kim from South Korea. The unique international environment offered by Trieste Observatory has allowed the researchers to progress further in their careers and they are now conducting their research in other top level internationally recognized institutions. The ERC grant has determined great progress in this field and a unique opportunity for all the cosmoIGM team.