———————- YEAR 2017 ———————–
23-05-2017, 11:00 – Room IB09, ARTOV
Intermittent Turbulence in the Heliosheath and Magnetosheath Plasmas
Dr. Wieslaw M. Macek (Space Research Centre, Polish Academy of Sciences, Warsaw, Poland; Cardinal Stefan Wyszyński University, Warsaw, Poland)
Abstract: Turbulence is complex behavior that is ubiquitous in space, including the environments of the heliosphere and the magnetosphere. Our previous studies on solar wind turbulence, including the heliosheath [1], and even at the heliospheric boundaries [2], also beyond the ecliptic plane [3], have shown that turbulence is intermittent in the entire heliosphere. As is known turbulence in space plasmas could often exhibit a substantial deviation from the normal distribution. Therefore, we also analyze the fluctuations of plasma and magnetic field parameters in the magnetosheath at the Earth’s bow shock. In particular, based on THEMIS observations, we have suggested that turbulence behind the quasi-perpendicular shock is more intermittent with larger kurtosis then that behind the quasi-parallel shocks [4]. Following this study we would like to present detailed analysis of the level of intermittency in the magnetosheath depending on various characteristics of plasma behind the bow shock and near the magnetopause. In particular, we have verified that at higher Alfvénic Mach numbers fluctuations are often more intermittent than at the lower numbers. However, the level of intermittency for the outgoing waves seems to be similar as for the incoming waves. We hope that the difference in characteristic behavior of these fluctuations in various regions of space plasmas can help to detect some complex structures in space missions in the near future.
17-05-2017, 11:00 – Room IB09, ARTOV
The Athena project and its science objectives
Dr. Matteo Guainazzi (European Space Research and Technology Centre, Noordwijk, The Netherlands)
Abstract: In this talk I will present the scientific objectives and design status of Athena – the Advanced Telescope for High-ENergy Astrophysics. Athena was selected in June 2014 as the second L-class mission in ESA’s Cosmic Vision 2015-25 plan, with a launch foreseen in 2028. It is an X-ray observatory designed to address the two questions of Cosmic Vision science theme ‘The Hot and Energetic Universe’: a) How does ordinary matter assemble into the large-scale structures we see today? and; b) How do black holes grow and shape the Universe? It will achieve these goals by studying a wide range of astrophysical phenomena: the formation and evolution of groups and clusters of galaxies; the chemical evolution of hot baryons; feedback effects of active
galactic nuclei; missing baryons thought to populate the intergalactic medium; the formation and early growth of black holes; and the accretion by super-massive black holes through cosmic time, among others. These goals will be achieved through an unprecedented combination of an X-ray telescope with a focal length of 12 m and an effective area of ~2 square meters at 1 keV, and two instruments: an X-ray Integral Field Unit (X-IFU) for spatially-resolved, high spectral resolution (~2.5 eV) imaging spectroscopy over a ~5’x5′ field-of-view, and a Wide Field Imager (WFI) for high count rate, moderate resolution spectroscopy over a large field of view (~40’x40′). The mission is currently in the study phase (“Phase A”) aiming at the scientifically optimal
design. Upon completion, Athena will be proposed for ‘adoption’ around 2019.
25-01-2017, ore 11:00, Aula IB09 ARTOV
Gravity: Where Do We Stand? (Springer, 2016) Presentazione del libro
Roberto Peron (INAF-IAPS)
Abstract: È recentemente uscito per i tipi Springer il libro “Gravity: Where Do We Stand?” (Peron, Colpi, Gorini, Moschella, Ed.). Questo libro ha avuto origine dall’organizzazione della Scuola SIGRAV 2009, dal titolo omonimo, tenutasi a Villa Olmo (Como), estendendo e integrando successivamente gli argomenti trattati. Il tema è l’attuale stato delle conoscenze del fenomeno “gravitazione”, nelle sue varie sfaccettature e su di un ampio intervallo di scale. Ogni capitolo del libro è stato concepito come gradino di una progressione che parte dalla scala di laboratorio, per allargarsi poi a fenomenologie sempre più vaste, dallo spazio circumterrestre al sistema solare a sistemi astrofisici. Ampio spazio è stato dato a questioni di carattere fondazionale, avendo al contempo sempre cura nel sottolineare lo stretto legame fra formulazioni teoriche e verifiche sperimentali. Una parte consistente è stata quindi dedicata ai molti problemi aperti in astrofisica e cosmologia, che chiamano costantemente in causa la gravitazione come motore di molti dei fenomeni osservati.
Il libro verrà presentato da uno dei curatori, ed è prevista la presenza di alcuni degli autori dei capitoli.
20-01- 2017, ore 15:00, Aula IB09 ARTOV
Five years of RadioAstron: pushing the angular resolution limit with Space-VLBI
Gabriele Bruni (Max Planck Institute for Radio Astronomy)
Abstract: During the five years after its launch, the Space-VLBI antenna RadioAstron has broken the records of the highest angular resolution obtained in astronomy, and used its resolutive power to probe brightness temperatures in AGN that exceeds the inverse Compton catastrophe limit. Three key science projects are devoted to the study of AGN physics, from jet launching/collimation to magnetic fields structure, taking advantage of the great detail offered by RadioAstron together with a global supporting ground array of radiotelescopes. I will review the main results of the three KSPs, and the technical challenges that have been overcome in data correlation and processing during these years.