seminari 2020

Europe/Rome
Dipartimento di Fisica e Scienze della Terra

Dipartimento di Fisica e Scienze della Terra

Via Saragat 1, Blocco C, 44122 Ferrara
Description

Seminari di Fisica del Dipartimento di Fisica e Scienze della Terra dell'Università di Ferrara e dell'INFN, sezione di Ferrara

    • 15:00 16:00
      Accelerators in the clouds: Terrestrial Gamma-ray flashes from discovery to the ASIM mission onboard the International Space Station. 1h

      Terrestrial Gamma-ray Flashes (TGFs) are submillisecond bursts of photons with energies up to several tens of MeV originating from thunderstorms and lightning, and are the manifestation of the most energetic natural particle acceleration processes occurring on Earth. TGFs were first discovered in the early 90s by the BATSE instrument onboard the Compton Gamma-Ray Observatory, and later observed by the RHESSI, AGILE and Fermi missions, all of them devoted to high-energy astrophysics. These missions provided all TGF observational evidences from space until the launch of the Atmosphere-Space Interaction Monitor (ASIM) mission.
      ASIM is a mission of the European Space Agency (ESA) dedicated to the observation of optical and high-energy transient emissions associated to thunderstorm and lightning activity: Transient Luminous Events (TLE) and Terrestrial Gamma-ray Flashes (TGF). ASIM overall main science goals are the understanding of the physics of TLEs and TGFs, their relation to lightning and their global impact to the high-altitude atmosphere and the geospace. ASIM was launched on April the 2nd 2018 and installed on the external facility of the Columbus module of the International Space Station, and is in nominal operations since June 2018.

      In this presentation I will first set the stage on TGF science and observations, and show how high-energy astrophysics mission became major players in a scientific field far away from the original main science goals of these missions. Then I will review the ASIM payload and mission objectives and present the key scientific results of the mission after 18 months of nominal operations concerning TGF morphology and imaging, and the TGF / lightning / TLE relationship.

      Speaker: Martino Marisaldi (Birkeland Centre for Space Science, University of Bergen, Norway. )
    • 14:30 15:30
      Cosmic Magnetism and the CMB 1h Aula C412

      Aula C412

      Relic magnetic fields generated in the primordial Universe may represent the seeds for the generation of the magnetic fields observed today on cosmological scales in galaxies, clusters, filaments and voids.
      Such Primordial Magnetic Fields (PMFs) can be generated through different mechanisms in the early Universe and their presence and characteristics would represent a peculiar probe of the fundamental physics in the early Universe like during inflation and phase transitions.
      Magnetic fields generated prior to recombination leave unavoidable imprints on the Cosmic Microwave Background which represents the best lab to investigate the nature of primordial magnetism.
      After presenting the observational and theoretical scenario of cosmic magnetism and the relevance of PMFs, I'll describe the main imprints of PMFs on CMB anisotropies with particular interests for the E and B polarizations.
      I will then show the most updated constraints on PMFs from Planck 2018 data and the forecasts for LiteBIRD and its combination with ground based CMB experiments.

      Speaker: Daniela Paoletti (INAF Bologna)
    • 14:30 15:30
      Precision cosmology with CMB lensing, delensing and cross-correlation with galaxy surveys 1h Aula C412

      Aula C412

      The upcoming generation of CMB polarization experiments (Simons Observatory, CMB-S4) and large-scale structures (LSS) surveys (Euclid, LSST) will map the matter distribution of the universe using the weak gravitational lensing effect. Being able to model this effect with the required level of precision will be mandatory in order to exploit these observables and their cross-correlations for cosmological applications.
      After reviewing the status of CMB and galaxy surveys cross-correlation, I will discuss recent developments in the theoretical modeling of CMB lensing and its cross-correlation with LSS probes including the non-linear evolution of the matter distribution and consequences of multiple deflections of photons. In the second part of the talk I will discuss the
      recent results of POLARBEAR, one of the current ongoing CMB polarization experiments. I will focus in particular on its recent analysis that achieved delensing of B-modes of CMB polarization using CMB data alone, paving the way for the optimal analysis of experiments of the next decade that will improve our knowledge of inflation by more than an order of
      magnitude.

      Speaker: Giulio Fabbian (University of Sussex (UK))
    • 16:30 17:30
      Gauge field production from a rolling axion: applications to the early and late universe 1h Aula C412

      Aula C412

      We will discuss several consequence of the gauge field production from an axion field that is evolving either during the
      primordial or the current accelerated stage of expansion of the universe.
      In the first case, the produced gauge field can source non-Gaussian scalar perturbations, the seeds of Primordial Black- Holes (PBH), and Gravitational Waves (GW) at CMB and at interferometer scales. Motivated by this, we will also discuss strategies for the characterization of the Stochastic GW background of cosmological origin. In the late universe application, we will discuss the possibility that the gauge field production provides an additional friction for the motion of the pseudo-scalar, so that the pseudo-scalar can behave as dark energy also in potentials that are too steep to lead to accelerated expansion in absence of this production.

      Speaker: Marco Peloso (Università di Padova)
    • 14:30 15:30
      A microscopic equation of state for neutron star matter 1h Aula 412C

      Aula 412C

      I will discuss the derivation of a microscopic equation of state of
      neutron star matter suitable for application to neutron stars merging and core collapse supernovae. I will focus on the various possibilities concerning the composition of neutron star matter and on the theoretical problems about the modeling of the different scenarios. In particular, I will consider both the mechanism that may lead to the formation of hyperons in the core of neutron stars, as well as the possibility that hadronic matter undergoes a phase transition to deconfined quark matter.
      Astrophysical consequences and possible signatures in merging neutron stars will be discussed.

      Speaker: Domenico Logoteta (Università di Pisa)
    • 11:00 12:00
      The Unreasonable Effectiveness of Physics in Society 1h

      "Physics provides an incredible impact on the economies”. This claim will be addressed in an outreach mode, in particular by presenting the selected examples from European particle physics. In this context, special attention will be paid to accelerator and detector technologies. Some quantitative economic measures of the “usefulness” of the abovementioned fields of science, will be given as well.

      Speaker: Tadeusz Lesiak ( IFJ-PAN (Cracovia) )
    • 11:00 12:00
      Future prospects for space missions in astrophysics 1h Aula C 412

      Aula C 412

      ESA and NASA are currently planning their future space missions in astrophysics, with processes respectively called "Voyage 2050" and "Decadal". Which are the prospects, the boundary conditions, the decisions to be made, in the light of current programs and expected developments, both in technology and for ground-based observations?

      Speaker: Fabio Favata (Head of the Strategy, Planning and Coordination Office Directorate of Science European Space Agency)
    • 10:00 12:00
      SUSY type dark matter in R^2 cosmology 2h Aula C412

      Aula C412

      We describe the cosmological evolution in the R^2 inflationary model (Starobinsky inflation). It is shown that in the post-infationary stage when the universe expansion is dominated by the oscillating curvature scalar, the particle kinetics is significantly different from the conventional Friedmann one. Thanks to that the density of heavy supersymmetric type relics, satisfying the LHC bounds could be sufficiently low to allow them to make the observed dark matter density.

      Speaker: Elena Arbuzova (Dubna State University and Novosibirsk State University)
    • 14:30 16:30
      Present day status of primordial black holes (PBH) 2h Aula C 412

      Aula C 412

      During several recent years PBH became a viable and very popular candidates for darkmatter particles. Moreover, the abundance of the observed black holes in the universe in all mass intervals is found to be unexpectedly high. It is tempting to conclude that the observed BH are predominalty primordial. The pro and contra observational data are analyzed. The mass spectrum of BH is discussed.

      Speaker: Alexander Dolgov (Dubna State University and Novosibirsk State University)
    • 10:00 12:00
      Problems of spontaneous and gravitational baryogenesis 2h Aula C 412

      Aula C 412

      Spontaneous and closely connected with it gravitational baryogenesis are very interesting examples of the baryogenesis scenarios permitting to realize successful generation of the baryon asymmetry, which violates two out of three Sakharov conditions, namely the symmetry can be generated in thermal equilibrium without explicit C/CP violation. It is argued that the traditional interpretation of the inherent (pseudo)Goldstone field as baryonic chemical potential is questionable but the magnitude of the asymmetry remains reasonably large. On the other hand, it is argued that gravitational baryogenesis leads to strongly unstable cosmology and is excluded in the original scenario.

      Speaker: Elena Arbuzova (Dubna State University and Novosibirsk State University)
    • 14:30 16:30
      Striking physical phenomena around Black Holes 2h Aula C 412

      Aula C 412

      Several examples of unusual physical effects around black holes,
      discussed in several publications mostly many years ago but which are mostly not widely known, are discussed. Among them are: superluminous propagation of light, proton-to-positron transformation, possible non-conservation of electric charge and cosmological electric asymmetry and some more.

      Speaker: Alexander Dolgov (Dubna State University and Novosibirsk State University)
    • 15:00 16:00
      Measuring the polarization of Gamma-Ray Bursts (GRB) prompt photons. 1h Aula C412

      Aula C412

      A lot of understanding of GRB have come from the discovery of the afterglows and of the GRB related phenomena (gravitational waves, supernova). But the central engine itself is still not well understood. The most pristine signal we can get from the central engine comes to us in three form: gravitational waves, neutrino and gamma ray photons.
      Gravitational waves just entered the game lately. GRB neutrinos are not yet observed.
      So, for a while, our best way to get a handle on the central engine is to use all the information we can squeeze out of gamma rays. One of this information is encoded in the polarization and has not been used by classical detector.
      The POLAR detector had the goal to make the first convincing measurements of GRB polarization. The results of the six months of data taken by POLAR in 2016-2017 will be discussed. I will also address the lessons we learned from the detector performances. I will also describe POLAR-2 a ten time more sensitive detector that has been selected to be flown in 2024 on the Chinese space station.

      Speaker: Nicolas Produit (Astronomical Department, University of Geneva, Switzerland, and Principal Investigator of the astroparticle experiment POLAR)