Weekly Seminars for March 2010

Friday 5th March 2010 - 4:00 P.M.

Università "La Sapienza" Roma - Aula Majorana (Physics Dept., Old Building - Ground Floor)

Speaker:  Dr. Roberto Peron (Istituto di Fisica dello Spazio Interplanetario (IFSI-INAF), Experimental Gravitation Group)

Title: Lo sviluppo dell'accelerometro ISA per BepiColombo e le attività del Gruppo di Gravitazione Sperimentale IFSI-INAF per la fisica fondamentale, l'esplorazione del Sistema Solare e la geofisica 

Abstract: In questo seminario verrà illustrato lo sviluppo da parte del Gruppo di Gravitazione Sperimentale IFSI-INAF dell'accelerometro ISA (Italian Spring Accelerometer) per la missione ESA BepiColombo, dedicata all'esplorazione del pianeta Mercurio e a importanti verifiche della teoria della relatività generale. ISA darà un fondamentale contributo agli esperimenti di radioscienza che studieranno campo gravitazionale, rotazione e traiettoria del pianeta intorno al Sole, misurando con estrema precisione le perturbazioni non gravitazionali agenti sull'MPO (Mercury Planetary Orbiter), tramite il quale verranno effettuati questi esperimenti. Una seconda parte del seminario verrà dedicata alle altre attività del Gruppo, con esperimenti e sviluppo di strumentazione per la fisica fondamentale, l'esplorazione del Sistema Solare e la geofisica.

Thursday 11th March 2010 - 4:00 P.M.

Università "La Sapienza" Roma - Aula Majorana (Physics Dept., Old Building - Ground Floor)

Speaker:  Dr. Massimiliano Lattanzi (ICRA - Dipartimento di Fisica)

Title: Status of the Standard Cosmological Model after the 7-year WMAP data

Abstract: In this talk I will review our current knowledge of the Universe, in the light of the latest observations of the WMAP satellite. I will first discuss the minimal, six-parameters LCDM model. Then I will discuss parameters beyond the minimal set, mainly focusing on the neutrino mass, on the effective number of relativistic species and on the dark energy equation of state parameter.

Tuesday 16th March 2010 - 2:00 P.M.

Università "La Sapienza" Roma - Aula Conversi (Physics Dept., Old Building - 1st Floor)

Speaker:  Dr. Valenti Bosch-Ramon (Max Planck Institut fuer Kernphysik)

Title: The physics behind the non-thermal emission in gamma-ray binaries

Abstract: Gamma-ray binaries consist of two components, generally a massive star and a compact object (neutron star or black hole), and show broadband non-thermal emission and outflows/jets. These objects should be relatively common in the galaxy, the main limit to the number of known systems being the sensitivity of the current gamma-ray instrumentation. Gamma-ray binaries are compact, and can produce non-thermal emission of persistent and flare nature in the whole electromagnetic domain, and perhaps also very high-energy neutrinos. The recent observational findings show that these objects can be extremely powerful accelerators and gamma-ray emitters, in which a complex interplay takes place between the companion star, the compact object, the accelerator of the relativistic particles, and the emission from the latter. Presently, thorough investigations are being carried out to understand how this interplay works, in order to explain observations. In this talk, I will briefly present the main results of these investigations, which are on-going.

Wednesday 31st March 2010 - 11:30 A.M.

ICRANet Seminar 

Speaker:  Dr. Marco Pizzi (Physics Dept., University of Rome “Sapienza” and Physik Dept., Freie Universitat Berlin)

Title: On the incompleteness of the Unruh modes in Minkowski spacetime 

Abstract: A review is given about the role of the boundary conditions in the Unruh "effect". Following the works by Narozhny, Fedotov, Karnakov, Mur, and Belinski, it is showed that the Unruh quantization has a meaning only on the "double wedge", i.e. on the right and left sector of Minkowski spacetime, with a zero boundary condition on the light cone. Such a condition is incompatible with the quantization of a free field in Minkowski spacetime. Dropping out this boundary condition the Unruh quantization can still have a meaning only if the light cone it cutted out. Again, in this case the Unruh modes constitute an incomplete basis for the whole Minkowski spacetime. Connections with the Hawking effect are also discussed.