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Astro & GW Colloquium

Galactic-scale outflows in galaxies of the local Universe

Speaker: Guido Roberts-Borsani (University College London)
Date: Wednesday 12 June 2019
Time: 14:00
Venue: Queens Buildings N/3.28

The ΛCDM cosmological framework has been extremely successful in reproducing observations and scaling relations of galaxies, however a severe limitation of the model is its overprediction of low and high mass galaxies: gas cools too soon and forms too many stars, despite star formation being extremely inefficient. Furthermore, large reservoirs of metal-enriched gas are observed in the circumgalactic medium of galaxies through quasar sightlines, even though metals are produced in stars within the galaxy disk. How did the gas get there and why is there such tension between observations and theory? Galactic-scale gas outflows are thought to solve the problem: intense pressure from star formation or a supermassive black hole ejects large amounts of metal-enriched gas out of a galaxy and can quench the star formation in the disk. But outflows are not well understood: are they present in all galaxies? Do they eject enough (cold) gas to stop star-formation in their hosts? What is the multiphase nature of outflows? How does an AGN affect them? In this talk I will give an overview of our current understanding of outflows and their importance in galaxy evolution studies, describe the observational surveys and methods used to detect and characterise them, and highlight recent results using spectroscopic (integrated and IFU) data from the SDSS, MaNGA, xCOLD GASS, xGASS and ALFALFA spectroscopic surveys for normal galaxies in the local Universe.