Interview | Matter ＆ the Universe | Astrophysics | Physics
Emanuele Daddi - Understanding the physics of galaxy formation and evolution (Upgal)
Galaxies are born, grow and die. They also have a “social life” by coming together to form clusters. The lives of the galaxies is at the heart of Emanuele Daddi’s research. From 2009 to 2014, he led an ERC research project, called Upgal, to understand the physics of galaxy formation and evolution.
“My work is constantly fuelled by new observations. We follow different tracks, without knowing in advance which will be the most successful. One of them is to study the content of the gas reservoirs in galaxies where new stars form,” says Emanuele Daddi. “The problem is that our immediate environment is rich in old galaxies that form a few stars only, if any. To understand the formation of galaxies and clusters, we must go back in time and observe the early universe, about 10 billion light-years away.” The first surprise was that the gas from these galaxies weigh as much as all their stars, although the relative weight of the gas is only 5-10% in the nearer universe.
Daddi and his team were the first to “see this simplicity”: the growth of a galaxy is essentially a result of its gaseous mass. Yet many other mysteries remain. Why do galaxies that are initially flat and circular stop forming stars and become spheroidal? What is the contribution of the central black hole in these processes? What is the impact of galaxy collisions and their subsequent merger? How is it possible that galaxies a hundred times denser than those of the nearby universe formed 10 billion years ago?
“To test the various models developed by theorists, we try to find new techniques of observation, at different wavelengths. For the first time, we observed the CO emission lines of normal distant galaxies to estimate the gaseous mass. Another method is to analyze the content of dust mixed with gas. We are also very excited about the future measurements of atomic carbon that will be made possible by the Atacama Large Millimeter Array in Chile. “
Emanuele Daddi (CEA Institute of Research into the Fundamental Laws of the Universe) conducted a research project from 2009 to 2014 to understand the physics of galaxy formation and evolution that was selected by European Research Council and received a fund of € 939,000.