X-Ray Spectroscopy of Ejecta and Compact Objects in Supernova Remnants

This thesis is devoted to the analysis of X-ray observations of supernova remnants (SNRs), exploiting the diagnostic potential provided by X-ray spectroscopy and complementing it with the synthesis of X-ray observables from multi-dimensional hydrodynamic (HD) and magneto-hydrodynamic (MHD) models. I tackle three open issues: the search for a spectral signature to correctly recover abundance and mass values of the stellar fragments ejected in the SN explosion through their X-ray spectra; the study of anisotropies and the origin of overionized plasma in the mixed-morphology SNR IC 443; the quest for the elusive compact object in SN 1987A.Comment: PhD Thesi

Superconducting Josephson-Based Metamaterials for Quantum-Limited Parametric Amplification: A Review

In the last few years, several groups have proposed and developed their own platforms demonstrating quantum-limited linear parametric amplification, with evident applications in quantum information and computation, electrical and optical metrology, radio astronomy, and basic physics concerning axion detection. Here, we propose a short review on the physics behind parametric amplification via metamaterials composed by coplanar waveguides embedding several Josephson junctions. We present and compare different schemes that exploit the nonlinearity of the Josephson current-phase relation to mix the so-called signal, idler, and pump tones. The chapter then presents and compares three different theoretical models, developed in the last few years, to predict the dynamics of these nonlinear systems in the particular case of a 4-wave mixing process and under the degenerate undepleted pump assumption. We will demonstrate that, under the same assumption, all the results are comparable in terms of amplification of the output fields

4. Indigènes et Grecs à Lemnos à la lumière des fouilles d’Hephaestia

Un discreto corpus di fonti letterarie, mitografiche, storiche ed epigrafiche riguardanti le vicende dell’isola di Lemno, resa immortale dal Filottete di Sofocle, può esser messo a confronto con una documentazione archeologica divenuta particolarmente abbondante negli ultimi tempi. La scoperta di un abitato del Bronzo Recente può ora dare concretezza storica all’attestazione di Lemnii nelle tavolette di Pilo e di Crosso. Un altro indicatore fondamentale è costituito dalla cessazione delle importazioni di ceramica micenee (che comunque continua ad essere imitata localmente) e dalla presenza massiccia di ceramica grigia di tipo anatolico ben nota sul continente di fronte, a partire da Troia. Si tratta di una cesura netta che segnala la nascita di una nuovo tipo di società, la stessa che seppellisce i morti nella necropoli ad incinerazione, in uso dal sec. VIII a. C., indagata dalla Scuola Italiana negli anni ’30. Ad un fase più avanzata (VII sec. a. C) risale la costruzione di un massiccio muro di cinta in grossi blocchi appena sbozzati. Infine, al VI secolo a. C si data una serie di edifici di culto (se ne contano quattro finora) caratterizzati dalla presenza di ampie sale destinate probabilmente a riti iniziatici.. Questo mondo cessa bruscamente si esistere (si tratta dell’aspetto più evidente che emerge dalla ricerca archeologica) con l’arrivo degli Ateniesi agli inizi del V secolo a.C

La mostra “Fiorentina Primaverile” del 1922

Inaugurated in Florence in 1922, the “Fiorentina Primaverile” was an important exhibition of Italian contemporary art, conceived by the writer Sem Benelli. This exhibition remains unique to Florence because of the number (more than three hundred) and the importance of the participants (from Andreotti and Wildt, to Conti and Bacci; from macchiaioli masters like Lega and Signorini to the young artists of «Valori Plastici») as well as for the moment when it took place: a fruitful period for artistic events, like the great exhibition of the Italian Paintings from the 17th and 18th Centuries. Analyzing the archival documents of the exhibition, that have been unpublished until now, this text aims to reconstruct in a historical and critical manner, for the first time, the “Fiorentina Primaverile”, in order to identify the true nature of the exhibition and, most of all, which kind of idea of Italian contemporary art was intended to be offered to the public

A quantum model for rf-SQUIDs based metamaterials enabling 3WM and 4WM Travelling Wave Parametric Amplification

A quantum model for Josephson-based metamaterials working in the Three-Wave Mixing (3WM) and Four-Wave Mixing (4WM) regimes at the single-photon level is presented. The transmission line taken into account, namely Traveling Wave Josephson Parametric Amplifier (TWJPA), is a bipole composed by a chain of rf-SQUIDs which can be biased by a DC current or a magnetic field in order to activate the 3WM or 4WM nonlinearities. The model exploits a Hamiltonian approach to analytically determine the time evolution of the system both in the Heisenberg and interaction pictures. The former returns the analytic form of the gain of the amplifier, while the latter allows recovering the probability distributions vs. time of the photonic populations, for multimodal Fock and coherent input states. The dependence of the metamaterial's nonlinearities is presented in terms of circuit parameters in a lumped model framework while evaluating the effects of the experimental conditions on the model validity

Unveiling pure-metal ejecta X-ray emission in supernova remnants through their radiative recombination continuum

Spectral analysis of X-ray emission from ejecta in supernova remnants (SNRs) is hampered by the low spectral resolution of CCD cameras, which creates a degeneracy between the best-fit values of abundances and emission measure. The combined contribution of shocked ambient medium and ejecta to the X-ray emission complicates the determination of the ejecta mass and chemical composition, leading to big uncertainties in mass estimates and it can introduce a bias in the comparison between the observed ejecta composition and the yields predicted by explosive nucleosynthesis. We explore the capabilities of present and future spectral instruments with the aim of identifying a spectral feature which may allow us to discriminate between metal-rich and pure-metal plasmas in X-ray spectra of SNRs. We studied the behavior of the most common X-ray emission processes of an optically thin plasma in the high-abundance regime. We investigated spectral features of bremsstrahlung, radiative recombination continua (RRC) and line emission, by exploring a wide range of chemical abundances, temperatures and ionization parameters. We synthesized X-ray spectra from a 3D hydrodynamic (HD) simulation of Cas A, by using the response matrix from the Chandra/ACIS-S CCD detector and that of the XRISM/Resolve X-ray calorimeter. We found that a bright RRC shows up when the plasma is made of pure-metal ejecta, and a high spectral resolution is needed to identify this ejecta signature. We verified the applicability of our novel diagnostic tool and we propose a promising target for the future detection of such spectral feature: the southeastern Fe-rich clump of Cas A. While there is no way to unambiguously reveal pure-metal ejecta emission with CCD detectors, X-ray calorimeters will be able to pinpoint the presence of pure-metal RRC and to recover correctly absolute mass and the chemical composition of the ejecta.Comment: 13 pages, 12 figures, accepted for publication in A&

The supernova remnant SN 1006 as a Galactic particle accelerator

The origin of cosmic rays is a pivotal open issue of high-energy astrophysics. Supernova remnants are strong candidates to be the Galactic factory of cosmic rays, their blast waves being powerful particle accelerators. However, super nova remnants can power the observed flux of cosmic rays only if they transfer a significant fraction of their kinetic energy to the accelerated particles, but conclusive evidence for such efficient acceleration is still lacking. In this sce nario, the shock energy channeled to cosmic rays should induce a higher post shock density than that predicted by standard shock conditions. Here we show this effect, and probe its dependence on the orientation of the ambient magnetic field, by analyzing deep X-ray observations of the Galactic remnant of SN 1006. By comparing our results with state-of-the-art models, we con clude that SN 1006 is an efficient source of cosmic rays and obtain an obser vational support for the quasi-parallel acceleration mechanism

Empowering Commercial Vehicles through Data-Driven Methodologies

In the era of “connected vehicles,” i.e., vehicles that generate long data streams during their usage through the telematics on-board device, data-driven methodologies assume a crucial role in creating valuable insights to support the decision-making process effectively. Predictive analytics allows anticipation of vehicle issues and optimized maintenance, reducing the resulting costs. In this paper, we focus on analyzing data collected from heavy trucks during their use, a relevant task for companies due to the high commercial value of the monitored vehicle. The proposed methodology, named TETRAPAC, offers a generalizable approach to estimate vehicle health conditions based on monitored features enriched by innovative key performance indicators. We discussed performance of TETRAPAC in two real-life settings related to trucks. The obtained results in both tasks are promising and able to support the company’s decision-making process in the planning of maintenance interventions