Elucidating the role of gas flows around galaxies with 3D observations and numerical simulations – 3DGASFLOWS

In the era of precision cosmology, astronomers still need to understand how intergalactic gas flows into the potential wells of galaxy halos, and how supernovae eject gas, metals, and energy back into the intergalactic medium. Regarding inflows, a variety of observations have indicated, albeit indirectly, that continuous replenishment of the gas reservoir of galaxies must have occurred, but direct evidence for accretion has been very elusive. In contrast, evidence of outflows or galactic-winds are so numerous that outflows are thought to be ubiquitous, but our knowledge of their physical properties is still in its infancy after decades of research in this area.
Our poor knowledge on gas-flow properties limits our ability to produce accurate numerical simulations. Gas in- and out-flows play a critical role in regulating the growth of galaxies. This ANR project aims at putting direct constraints on both in- and out-flow processes through innovation around 4 fronts: (i) through observations using the non-conventional technique of background quasars whose line of sight passes near star-forming galaxies; (ii) through an observational campaign using novel techniques to spatially map outflows in emission using two state-of-the-art IFU surveys which will, by their instrumental or survey design, yield thousands of high signal-to-noise galaxies across cosmic times, enabling us a new view on galactic winds; (iii) a study of molecular gas content with millimeter interferometers; and (iv) through a theoretical approach using state-of-the-art hydrodynamical simulations and radiative transfer models. The proposed program will allow us to study the circum-galactic medium to an unprecedented level of details with new techniques, to confront the theoretical expectations of cooling and accretion, and to enable major advances in our understanding of the properties of galactic flows.
The proposed research gathers French theoreticians and observers in these areas, which will reinforce transverse collaborations. The scientific program for this ANR is organized into four main work-packages (WP). WP1 will analyze the 100+ galaxy-quasar pairs obtained with MUSE and UVES instruments. WP2 will focus on the study of emission signatures of outflows using emission lines. WP4 and WP5 will develop and analyze new generations of numerical simulations. WP3 will study the relation between the molecular gas content, the metallicity, the star formation rate and the stellar mass of galaxies over several Gyrs. Two additional WPs, a management WP (WP0) and a dissemination/outreach WP (WP6) will complete this program which is scheduled for 4 years in 2018-2021. This program will pave the way for the exploitation of the next generation of major European facilities such as E-ELTs. Given the large investment made by France in building MUSE, this proposal will provide the resources needed for maintaining a leadership position in the field, guaranteeing a proper scientific return. The resources needed to complete this program are a 3-yr post-doc, essential for WP2, and a 3-yr postdoc essential for the analysis of simulations in WP4 and WP5. The associated costs amount to 460kEur. Upon completion, this 3DGasFlows program will deliver breakthroughs in our understanding of the complex processes that are regulating galaxy growth.