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You are here: Home Research Activities Galaxies and Cosmology Origin and evolution of the galaxies and structure

The evolution of galaxies

In the standard cold dark matter model, galaxy formation occurs hierarchically. At least this is what happens to the dark matter component, that collects into ever-larger structures (the halos mentioned above) via a process of gravitational interaction and successive merger. Although driven gravitationally by dark matter, what happens to the baryonic component could be very different. In general it is thought that the latter collapses in the potential wells created by dark matter, in what is called dissipative collapse, converting primordial gas into stars. This could be the origin of the most massive galaxies, the ellipticals, and in general of the spheroidal component observed in spiral galaxies. In this latter case, the disks form around the spheroid as the result of a slow and continuous acquisition of gas from the regions around the galaxy. This gas acquires angular momentum and contributes to the formation of the younger stellar population, as well as providing the fuel for successive generations. In this process, both the initial mass of the dark matter halo in which the galaxy forms and the environment in which it finds itself play an important role. It is well established, for example, that in galaxy clusters, or in regions of high density, the fraction of spiral galaxies is very low. The last 15 years have seen great progress in this field, with an important contribution from the Italian astronomical community both through the above mentioned surveys, VVDS and COSMOS-ZCOSMOS, and other projects (for example GMASS and GOODS), equally important for the understanding of the evolutionary phenomena that guide the history of the galaxies. On this qualitative picture there is general agreement, even if details such as the epoch of formation of disks or the relative role of mass and environment in defining the properties of forming galaxies are still poorly defined, also due to the dearth of available samples at redshift z>1.5-2.

Space, ASI’s Sardinia Deep Space Antenna inaugurated

Sep 09, 2017

Space, ASI’s Sardinia Deep Space Antenna inaugurated The SDSA is located at the Sardinia Radio Telescope-SRT: the large radio telescope for the study of the Universe, situated near Cagliari and developed by the National Institute for Astrophysics-INAF in collaboration with ASI, Regione Sardegna and the Ministry of Education, University and Research-MIUR.

Space, Let’s go to Mars

Sep 09, 2017

Space, Let’s go to Mars An educational video game to explore the Red Planet

Carina Nebula, INAF identifies new star formations

Sep 09, 2017

Carina Nebula, INAF identifies new star formations The Gaia-ESO Survey: Global properties of clusters Trumpler 14 and 16 in the Carina nebula study conducted by Francesco Damiani from INAF of Palermo, involving a number of researchers from the INAF observatories of Arcetri, Bologna, Catania, Padua and Palermo, has been recently published in Astronomy & Astrophysics.