GW170817, the first evidence of kilonovae existence. The Italian follow-up observations of GW triggers in the Multi-Messenger Era
On August 17th 2017 the first electromagnetic counterpart of a gravitational wave (GW) event originated by the coalescence of a double neutron star system (GW 170817, Abbott et al. 2017) was finally observed. A world-wide extensive observing campaign was carried out to follow-up and study this source.
In this talk I will describe the unique spectroscopic dataset acquired with the VLT which allowed to characterize and identify the optical counterpart of GW 170817 as the first compelling example of a "kilonova", a transient source powered by radioactive decay of heavy elements resulting from the r-process nucleosynthesis of ejected neutron star matter.
In this talk, I will present the activities we carried out to optimize the response of the Italian GRAWITA network of facilities to expected GW triggers and our results for past (O1 and O2) and current (O3) observing runs. All these activities are expected to provide means and opportunities to the Italian and European astronomical communities to have a leading role in the GW and Time Domain Astronomy in the future.
Friday, 21 February 2020, ore 14:30 — Sala Wataghin
Scattering amplitudes at the precision frontier: new methods for multi-scale problems
Dealing with the complexity of perturbative scattering amplitudes has always been a major challenge when keeping theory uncertainties in line with high energy collider experiments. In this talk I will review some techniques that are being used to overcome the current bottlenecks in two-loop amplitude computations. The use of numerical sampling over finite fields allows us to reconstruct fully analytic information and uncover simple representations for on-shell amplitudes.
Friday, 7 February 2020, ore 14:30 — Aula Magna "Tullio Regge"
The first image of a black hole
I will briefly discuss how the first image of a black hole was obtained
by the EHT collaboration. In particular, I will describe the theoretical
aspects that have allowed us to model the dynamics of the plasma
accreting onto the black hole and how such dynamics was used to generate
synthetic black-hole images. I will also illustrate how the comparison
between the theoretical images and the observations has allowed us to
deduce the presence of a black hole in M87 and to extract information
about its properties. Finally, I will describe the lessons we have
learned about strong-field gravity and alternatives to black holes.
Wednesday, 29 January 2020, ore 10:00 — Aula A
Entanglement and thermodynamics in non-equilibrium quantum systems
Entanglement and entropy are key concepts standing at the foundations of quantum and statistical mechanics. In the last decade the study of the non-equilibrium dynamics of isolated quantum systems revealed that these two concepts are intricately intertwined. Although the unitary time evolution ensuing from a pure initial state maintains the system globally at zero entropy, at long time after the quench local properties are captured by an appropriate statistical ensemble with non zero thermodynamic entropy, which can be interpreted as the entanglement accumulated during the dynamics. Therefore, understanding the post-quench entanglement evolution unveils how thermodynamics emerges in isolated quantum systems.
Friday, 17 January 2020, ore 14:30 — Aula C
Properties of strongly interacting matter from first principles
Quantum Chromodynamics (QCD) is the fundamental theory describing the interactions between the ultimate building blocks of matter, namely quarks and gluons. At temperatures as high as trillions of degrees Kelvin and zero net baryon density, first principle Lattice QCD calculations have shown that a smooth crossover transition occurs between hadronic matter and a new state of matter called the quark-gluon plasma. A remaining question in QCD is whether criticality may appear at large baryon densities. In this talk I will review the status of lattice QCD simulations of strongly interacting matter at zero and finite density. I will also discuss ways to push our investigations to larger baryon densities, to support the forthcoming experimental program at Brookhaven National Laboratory.
Friday, 20 December 2019, ore 14:45 — Aula Magna "Tullio Regge"
Symmetries in physics: historical-philosophical reflections
As is well known, considerations based on the group theoretical notion of symmetry dominate modern physics, at all scales of the physical description. In the philosophy of science community, the role and meaning of physical symmetries is a relatively recent subject and, apart from some notable exceptions, literature devoted to systematic philosophical reflection on the issue started to appear at the beginning of this century. Since then, the subject has flourished and such issues as the significance of gauge symmetry, quantum particle identity in the light of permutation symmetry, the role of symmetry breaking, the empirical status of symmetry principles have become most discussed topics in today's philosophy of physics.
The talk aims at giving a survey of this debate's main points and arguments, highlighting how the issues discussed relate to more traditional problems in the philosophy of science, such as the status of the laws of nature and, more generally, the relationships between mathematics, physical theory and the world. To lend some depth to the survey, the talk begins with some historical remarks, including a brief description of the historical roots and emergence of the concept of symmetry at work in modern physics.
Friday, 22 November 2019, ore 14:30 — Sala Wataghin
Universes as Bigdata: Superstrings, Calabi-Yau Manifolds and Machine-Learning
We review how historically the problem of string phenomenology lead theoretical physics first to algebraic/diffenretial geometry, and then to computational geometry, and now to data science and AI.
With the concrete playground of the Calabi-Yau landscape, accumulated by the collaboration of physicists, mathematicians and computer scientists over the last 4 decades, we show how the latest techniques in machine-learning can help explore problems of physical and mathematical interest.
Friday, 8 November 2019, ore 14:30 — Aula C
Exploring the early Universe through the cosmic microwave background
I will present the tightest observational bounds available on the early Universe, largely based on the legacy of the ESA Planck satellite. The emergent cosmological picture is well consistent with a simple Lambda Cold Dark Matter model arising out of an inflationary scenario. We do see, however, small quirks in the data that may or may not hint at new physics. High accuracy measurements expected within the next decade, aimed at CMB polarization, will prove critical for our understanding of the early universe. They are expected to push the model tests to unprecedented precision, shed light on the observed anomalies, and provide a direct window to cosmic Inflation by constraining the predicted background of primordial gravitational waves.
Thursday, 17 October 2019, ore 14:30 — Sala Wataghin
First demonstration of Antimatter Quantum Interference
Interference of matter waves is at the heart of quantum physics and has been observed for a wide range of matter particles from electrons to complex molecules. Here, I will discuss quantum interference of single positrons, obtained in the frame of the Quplas project, by means of a Talbot-Lau interferometer based on material diffraction gratings. This is the first interferometry experiment ever made with an antiparticle as well as the second demonstration of an elementary constituent single-particle interference.
Friday, 4 October 2019, ore 14:30 — Aula C