Galaxies in the box
The results of the team led by Monaco and Murante, in publication of Monthly Notices of the Royal Astronomical Society, are at the forefront in Italy and put the group in a very small elite international Trieste. How do you rebuild on the computer the evolution of spiral galaxies? It was the question asked by a group of astronomers from Trieste, providing a new look at the so-called galaxies in the box.
Our Sun and its planets and hundreds of billions of other stars in outer space to browse the edge of our galaxy, the Milky Way. The observations indicate that the Milky Way galaxy is a type of “spiral” widespread in the universe. It consists of a thin disk of relatively young and blue stars, dust and gas that form a spiral design and, at the center, it forms a core of old stars yellowish-reddish.
For astrophysicists, it was necessary figuring out how it was formed and what a galaxy means before being able to program a super-computer to follow the fundamental physical processes, starting from a very young Universe until the present cosmic epoch. The calculation is made on what astrophysicists call “a box”, a cube of Universe whose side can measure billion light years. The way of supercomputers has been traveled since the early 90s, but so far scientists have always found in front of a wall that precluded them to produce a realistic model of spiral galaxy. In particular, the disks of virtual galaxies were too compact and too fast in rotation around their center.
This situation has dramatically improved in the last two years thanks to the work of some international research groups and in particular of Pierluigi Monaco University of Trieste (UniTs) and Giuseppe Murante INAF-Osservatorio Astronomico di Trieste (INAF-OATs) and their collaborators Paramita Barai (INAF-OATs), Stefano Borgani (UniTs), Anna Curir (INAF-OATorino), Klaus Dolag (USM-Munchen), David Goz (UniTS), Antonio Ragagnin (USM-Munchen) and Luca Tornatore (INAF-OATs).
The results of the team led by Monaco and Murante, in publication of Monthly Notices of the Royal Astronomical Society, are at the forefront in Italy and put the group in a very small elite international Trieste. The novelty of the calculations that has overcome old obstacles is mainly due to the progress in understanding how supernovae, massive stars that die in gigantic explosions, act on the gaseous component of the galaxy, especially in the early stages of training. Their explosion throws the gas away from the galaxy, gas which then falls rather slowly ensuring a gradual formation of the stellar disk.
“Including this process in the calculation is extremely difficult,” says Giuseppe Murante, “the key to our success has been the development of a new model of sophisticated gas that forms stars. The next step will be to connect our models to simulations of small portions of the galaxy at very high resolution. ”
“Much work remains to be done to fully understand the mechanisms of formation of spiral galaxies,” adds Pierluigi Monaco. “In particular, we rely much on the information that we could get through the comparison between our predictions and future observations of properties of galaxies so far little explored.”