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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.

Thanks to the HARPS-N spectrograph, the TNG can see Venus

Feb 10, 2017

Thanks to the HARPS-N spectrograph, the TNG can see Venus TThe HARPS-N spectrograph succeeded in measuring from the Earth the velocity of the clouds in the atmosphere of Venus thanks to its high precision, competing with the Japanese Akatsuki probe, which has recently begun to study the atmosphere of the second planet.

The X-ray Universe 2017

Feb 03, 2017

The X-ray Universe 2017 The symposium (Rome, 6-9 June 2017) is the fifth meeting in the series of the international symposia "The X-ray Universe". The intention is to gather a general collection of research in high energy astrophysics. The symposium will provide a showcase for results, discoveries and expectations from current and future X-ray missions.

IXPE mission: Italy and NASA for new X-ray astronomy

Jan 21, 2017

IXPE mission: Italy and NASA for new X-ray astronomy NASA has announced that it is funding a new mission to study the high-energy Universe: it will be called IXPE (Imaging X-Ray Polarimetry Explorer) and will allow astronomers to explore with unprecedented details some of the most extreme astronomic objects, including stellar and supermassive black holes, neutron stars and pulsars. The mission, scheduled for the end of 2020, will count on a considerable Italian contribution through the Italian Space Agency(ASI), the National Institute for Nuclear Physics (INFN) and the National Institute of Astrophysics (INAF).