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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.

AN UNEXPECTED GAMMA-RAY BURST

Jun 08, 2022

AN UNEXPECTED GAMMA-RAY BURST An international group led by INAF researchers have confirmed that the gamma-ray burst GRB 200826A, which lasted less than two seconds – typical of short bursts – is associated with the explosion of a massive star, which is typical of long gamma-ray bursts

Announcing the new Director of the Large Binocular Telescope

May 31, 2022

Announcing the new Director of the  Large Binocular Telescope The Large Binocular Telescope Observatory, one of the largest and most advanced optical telescopes in the world, is proud to announce the appointment of its new Director, Prof. Joseph Shields, who will assume the position effective June 06, 2022

The final catalogue of the Gaia-ESO Survey is public

May 25, 2022

The final catalogue of the Gaia-ESO Survey is public ESO has just released the final catalogue of the Gaia-ESO Survey (GES), a large public spectroscopic survey carried out with the Very Large Telescope (VLT) of the European Southern Observatory in Chile. INAF has played a key role in all the aspects of the survey.