download report - Sapienza
download report - Sapienza
download report - Sapienza
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
Scientific Report 2007-2009<br />
Astronomy & Astrophysics<br />
Astrophysics<br />
The international year of astronomy just passed<br />
with flying colors, celebrating 400 years after the<br />
first scientific use of the telescope by Galileo Galilei,<br />
and his discoveries. Nowadays Astrophysics and<br />
Cosmology experience faster and faster growth<br />
worldwide, using the methods of experimental<br />
physics and the most advanced hardware and analysis<br />
technologies to study the universe, its content,<br />
its evolution and the physical phenomena happening<br />
in it. Our Department, located close to some of<br />
Galilei’s sites, is a driving partner of this cultural<br />
adventure.<br />
Astrophysicists observe the universe to discover<br />
its structures and phenomena, and use the laws<br />
of physics to describe the observations. But also<br />
they use the universe as a laboratory, with physical<br />
conditions so extreme (e.g. near black holes,<br />
or near the big bang) that cannot be created on<br />
the Earth. So they take advantage of these observations<br />
to test new physical theories and laws, an<br />
evident the strong synergy among physics, astrophysics<br />
and cosmology. Our Department makes no<br />
exception.<br />
The progress in Astrophysics and Cosmology has<br />
been very significant in the last 20 years. The highlights<br />
have been the discovery of gamma-ray bursts,<br />
Figure 1: The ”bullet cluster” of galaxies is a good<br />
example of an astrophysical system which must be<br />
studied in a variety of ways (dynamically, and with<br />
microwave, visible and X-ray observations), and can<br />
be used to constrain fundamental physics (dark matter).<br />
The figure is a composite of an optical image<br />
(showing the galaxies of the cluster), an image in X-<br />
rays (red, showing diffuse, ionized baryonic matter),<br />
and the density of dark matter (blue, as estimated by<br />
lensing of background galaxies). Future microwave<br />
observations of the Sunyaev-Zeldovich effect in this<br />
cluster will constrain the nature of dark matter. All<br />
these issues are investigated by astrophysicists in our<br />
Department. credit: NASA/ESO<br />
the study of the large scale structure of the universe with galaxy surveys and with gravitationallensing<br />
surveys, the detailed observation of structures in the cosmic microwave background, starting<br />
precision cosmology, and the discovery of the acceleration of the expansion of the universe.<br />
While all these are remarkable findings, they also pose fundamental questions, like:<br />
• Did the universe undergo an inflation phase at ultra-high energies ?<br />
• What is the nature of dark matter, and how does it affect the formation of structures ?<br />
• What is the nature of dark energy, and does it really exist ?<br />
• Is the estimated primordial abundance of 7 Li consistent with big bang nucleosynthesis ?<br />
• How do supermassive black-holes form and how are they fed so as to shine as Quasars ?<br />
• Which is the origin of gamma ray bursts ?<br />
• Which are the sources of cosmic rays and ultra-high energy cosmic rays ?<br />
• Which are the details of star formation and stars death ?<br />
The Astrophysics research carried out in our Department covers a wide range of areas, facing<br />
many of the questions above:<br />
• Stellar and Galactic Astrophysics, focusing on Astronomical Databases, Stellar systems<br />
structure, formation and evolution, Stability of relativistic stellar systems, Chemical evolution of<br />
galaxies, Measurements of the Galactic dust;<br />
• Extragalactic Astrophysics, focusing on the spectral evolution and variability of Active<br />
Galactic Nuclei, Galactic and extragalactic X and gamma rays, Search and analysis of galaxy<br />
clusters in the microwave, optical and X-ray bands;<br />
<strong>Sapienza</strong> Università di Roma 143 Dipartimento di Fisica