427 research outputs found
La passione di una vita: "Il lavoro su Ruzante" di Gianfranco De Bosio
No full textL'articolo analizza le principali caratteristiche dell regie ruzantiane di Gianfranco De Bosi
"Un non calmato stupore della “forma”". Gianfranco Contini traduttore di Hölderlin
No full textSaggio sull'attività traduttoria del filologo Gianfranco Contini, sulla natura e importanza di tale, lunga, esperienza nell'Europa degli anni '30-40 del XX secolo
"Il Pellicano" di Strindberg allestito dal Teatro dell’Università di Padova
No full textNella storica sala dei Giganti di Padova, sede privilegiata delle iniziali esibizioni del Teatro dell’Università, nel marzo del 1947 debutta il primo allestimento italiano del "Pellicano" (1907) di August Strindberg con la regia di Gianfranco De Bosio. Per rendere omaggio agli studi di Franco Perrelli, il contributo tenta di illuminare qui le circostanze e le caratteristiche di quello spettacolo
Second-order Fermi Reacceleration Mechanisms and Large-Scale Synchrotron Radio Emission in Intracluster Bridges
No full textRadio observations at low frequencies with the low frequency array (LOFAR) start discovering gigantic radio bridges connecting pairs of massive galaxy clusters. These observations probe unexplored mechanisms of in situ particle acceleration that operate on volumes of several Mpc3. Numerical simulations suggest that such bridges are dynamically complex and that weak shocks and super-Alfve ́nic turbulence can be driven across the entire volume of these regions. In this Letter, we explore, for the first time, the role of second-order Fermi mechanisms for the reacceleration of relativistic electrons interacting with turbulence in these peculiar regions. We assume the turbulent energy flux measured in simulations and adopt a scenario in which relativistic particles scatter with magnetic field lines diffusing in super-Alfve ́nic turbulence and magnetic fields are amplified by the same turbulence. We show that steep spectrum and volume filling synchrotron emission can be generated in the entire intracluster bridge region, thus providing a natural explanation for radio bridges. Consequently, radio observations have the potential to probe the dissipation of energy on scales larger than galaxy clusters and second-order Fermi mechanisms operating in physical regimes that are still poorly explored. This has a potential impact on several branches of astrophysics and cosmology
On the connection between radio mini-halos and gas heating in cool core clusters
No full textIn this work, we present a study of the central regions of cool-core clusters hosting radio mini-halos, which are di use synchrotron sources extended on cluster-scales surrounding the radio-loud brightest galaxy. We aim to investigate the interplay between the thermal and non-thermal components in the intracluster medium in order to get more insights into these radio sources, whose nature is still unclear. It has recently been proposed that turbulence plays a role for heating the gas in cool cores. A correlation between the radio luminosity of mini-halos, , and the cooling flow power, P_\rm CF, is expected in the case that this turbulence also plays a role for the acceleration of the relativistic particles. We carried out a homogeneous re-analysis of X-ray Chandra data of the largest sample of cool-core clusters hosting radio mini-halos currently available ( objects), finding a quasi-linear correlation, \nu P_\nu \propto P_\rm CF^0.8. We show that the scenario of a common origin of radio mini-halos and gas heating in cool-core clusters is energetically viable, provided that mini-halos trace regions where the magnetic field strength is
Lo “Stakeholder Paradox” nel dibattito nordamericano, la visione plurifinalistica di Vittorio Coda e l’etica del sistema aziendale
No full textRelic—Shock Connection in Abell 115
No full textGiant radio relics are arc-shaped diffuse sources with Mpc-scale found in the peripheries of some dynamically disturbed galaxy clusters. According to the leading scenario of relic formation, shock waves occurring in merger events amplify the local magnetic field and (re)accelerate particles. However, Mach numbers associated with merger shocks are typically low, and hence inefficient at accelerating particles from the thermal pool. We analyzed a deep Chandra observation (334 ks) to study the relic region in the cluster Abell 115. Temperature and surface brightness profiles taken across the relic both show a clear discontinuity, which is consistent with a shock. This result supports the relic–shock connection and represents a test case to study the origin of radio relics. In this particular case, we suggest that a re-acceleration scenario is more suitable. The relic morphology and position are consistent with a shock produced in an off-axis merger between clusters with different masses
Analysis of the Divider Control Policy for a Fractional Low-Power Time Synchronization Algorithm
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