| Weekly Seminars for November 2013 |
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Tuesday November 5,
2013 - 2,00 pm
Aula Rasetti (Physics Dept., Old Building - 2nd Floor)
Seminar of Astrophysics
Speaker: Dr. Federico PIAZZA
Institution: APC, Astroparticule et Cosmologie, Paris - France Title: Dark energy: an effective field theory approach.
Abstract:
The discovery of the accelerating expansion of the Universe is motivating an impressive amount of theoretical and observational activity. After briefly reviewing the problems and challenges of ``Dark Energy", I will focus on recent and ongoing works where a unifying description of dark energy and modified gravity is proposed, that is inspired by the Effective Field Theory (EFT) of Inflation formalism. By extending such a framework to late time cosmology one can write the most general action for cosmological perturbations in the presence of an additional scalar degree of freedom. I will focus on a few operators that are quadratic in the perturbations and which appear in non-minimally coupled scalar-tensor gravity and ``Galileon" theories and describe the mixing between gravity and the scalar degree of freedom that such operators produce. I will also discuss the present observational constraints and forecasts for future experiments such as EUCLID.
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La Segreteria ICRA
c/o Dipartimento di Fisica
Sapienza Università di Roma
P.le A. Moro, 5 I - 00185 ROMA, Italy tel.: +39 06 4991 4 254 fax: +39 06 4454992 email: segreteria@icra.it
Friday November 8,
2013 - 3,00 pm
Aula Rasetti (Physics Dept., Old Building - 2nd Floor)
ICRA Seminar
Speaker: Dr.ssa Elena ZANINONI
Institution: INAF - OA Brera and University of Padova Title: Gamma-ray burst optical light-curve zoo: comparison with X-ray observations.
Abstract:
Gamma-Ray Bursts (GRBs) are the most powerful sources of electromagnetic radiation in the Universe. There are many open questions about their origin and their nature, and the answers should be searched in the large amount of data collected during these last years. We focused on the study of the their X-ray and optical afterglow properties, as observed by the Swift X-Ray Telescope (XRT) and ground-based optical telescopes. We carried out a systematic analysis of the optical data available in literature for the GRBs observed between December 2004 and December 2010 to investigate the GRB emission mechanisms and to study their environment properties. Our analysis shows that the gas-to-dust ratios of GRBs are larger than the values calculated for the Milky Way, the Large Magellanic Cloud, and the Small Magellanic Cloud. In this talk I will show the major results of the analysis of this large set of data.
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La Segreteria ICRA
c/o Dipartimento di Fisica
Sapienza Università di Roma
P.le A. Moro, 5 I - 00185 ROMA, Italy tel.: +39 06 4991 4 254 fax: +39 06 4454992 email: segreteria@icra.it
Monday November 11,
2013 - 2,00 pm
Aula Conversi (Physics Dept., Old Building - 1st Floor)
Seminar of Astrophysics
Speaker: Dr. Ricardo GENOVA-SANTOS
Institution: Instituto de Astrofisica de Canarias, Tenerife - Spain Title: The QUIJOTE-CMB experiment: current status and future plans.
Abstract:
The QUIJOTE (Q-U-I JOint TEnerife) Experiment is designed to perform high sensitivity measurements of the polarization of the CMB and relevant foregrounds in the frequency range 10-40 GHz. The project consists of two telescopes and three instruments which will explore a large sky area (5000 sq deg) from the Teide Observatory (Tenerife). The Multi-Frequency Instrument (MFI) is performing routine observations of selected sky areas at 10-20 GHz since November 2012. The second telescope and two additional instruments at 30 and 40 GHz are currently under construction.
In this talk I will describe the goals of this project, in what concerns both its potential to correct for low-frequency polarized foregrounds (synchrotron and, if polarized, the anomalous microwave emission) and to set constraints on the tensor to scalar ratio at the level of r~0.05. I will also present some preliminary maps obtained with the MFI during the first year of operation of this experiment, in different sky regions dominated by synchrotron and anomalous microwave emissions.
**************************************************
La Segreteria ICRA
c/o Dipartimento di Fisica
Sapienza Università di Roma
P.le A. Moro, 5 I - 00185 ROMA, Italy tel.: +39 06 4991 4 254 fax: +39 06 4454992 email: segreteria@icra.it |