A5013926894- Solar and Space Plasma Dynamics
- Solar Radiation and Photovoltaics
- Astro and Planetary Science
- Gamma-ray bursts and supernovae
- Adaptive optics and wavefront sensing
- Ionosphere and magnetosphere dynamics
- Stellar, planetary, and galactic studies
- solar cell performance optimization
- Sparse and Compressive Sensing Techniques
- Atmospheric Ozone and Climate
- Geomagnetism and Paleomagnetism Studies
- Calibration and Measurement Techniques
- CCD and CMOS Imaging Sensors
- Photovoltaic System Optimization Techniques
- Radiation Therapy and Dosimetry
- Vehicle emissions and performance
- Medical Image Segmentation Techniques
- Particle Detector Development and Performance
- Distributed and Parallel Computing Systems
- Statistical Methods and Inference
- Medical Imaging Techniques and Applications
- Statistical and numerical algorithms
- Environmental Impact and Sustainability
- Toxic Organic Pollutants Impact
- Radio Astronomy Observations and Technology
FHNW University of Applied Sciences and Arts
2024-2025
Western Kentucky University
2022-2024
University of Genoa
2019-2023
Aims. The Spectrometer Telescope for Imaging X-rays (STIX) on Solar Orbiter is a hard X-ray imaging spectrometer, which covers the energy range from 4 to 150 keV. STIX observes bremsstrahlung emissions solar flares and therefore provides diagnostics of hottest (⪆10 MK) flare plasma while quantifying location, spectrum, content flare-accelerated nonthermal electrons. Methods. To accomplish this, applies an indirect bigrid Fourier technique using set tungsten grids (at pitches 0.038 1 mm) in...
Aiming to assess the progress and current challenges on formidable problem of prediction solar energetic events since COSPAR/ International Living With a Star (ILWS) Roadmap paper Schrijver et al. (2015), we attempt an overview status global research efforts. By refer flares, coronal mass ejections (CMEs), particle (SEP) events. The emphasis, therefore, is methods flares eruptions, as well their associated SEP manifestations. This work complements COSPAR Space Weather Action Teams (ISWAT)...
The Spectrometer/Telescope for Imaging X-rays (STIX) is one of six remote sensing instruments on-board Solar Orbiter. telescope applies an indirect imaging technique that uses the measurement 30 visibilities, i.e., angular Fourier components solar flare X-ray source. Hence, problem STIX consists inversion data measured by instrument. In this work, we show visibility amplitude and phase calibration 24 out sub-collimators has reached a satisfactory level scientific exploitation set methods...
The Spectrometer and Telescope for Imaging X-rays (STIX) on board Solar Orbiter observes solar X-ray emission in the range of 4 – 150 keV produces spectra images flares over a wide flare magnitudes. During nominal operation, STIX continuously generates data. A constant data flow requires fully automated data-processing pipelines to process analyze data, platform manage, visualize, distribute products scientific community. Data Center has been built fulfill these needs. In this paper,...
A major open issue concerning the active Sun is effectiveness with which magnetic reconnection accelerates electrons in flares. paper published by {\em{Nature}} 2022 used microwave observations to conclude that an almost ideal accelerator, energizing nearly all within a coronal volume nonthermal energies. Shortly thereafter, {\em{Astrophysical Journal Letters}} hard X-ray measurements \emph{of same event} reach contradictory conclusion less than 1\% of available were accelerated. Here we...
The Spectrometer/Telescope for Imaging X-rays (STIX) on board Solar Orbiter continuously measures the Sun in energy range 4-150 keV. Due to spacecraft’s peculiar orbit, around 50% of all STIX flares are backside and lack a corresponding GOES class. In Stiefel et al. (2025) we describe correlation between background detector measurements where found power-law function two data sets. This can be used get proxy class large flares.Building up approach using STIX, want discuss how...
The Sun manifests its activity across different temporal scales and via transient phenomena that start from solar flares and, through energetic particles, coronal mass ejections, wind, impact the whole heliosphere. understanding of causality this chain events is hampered by fact several open issues still bother a full comprehension trigger such chain, i.e., flares. present talk aims to shed some light on two specific aspects these elusive characterizing active Sun: determination volume...
Context. The Spectrometer/Telescope for Imaging X-rays (STIX) is the hard X-ray instrument onboard Solar Orbiter designed to observe solar flares over a broad range of flare sizes. Aims. We report first STIX observations microflares recorded during commissioning phase in order investigate performance at its detection limit. Methods. uses imaging spectroscopy between 4–150 keV diagnose hottest plasma and related nonthermal electrons. This result paper focuses on temporal spectral evolution...
Aims. We seek to determine what extent the problem of forward fitting visibilities measured by Spectrometer/Telescope Imaging X-rays (STIX) on board Solar Orbiter becomes more challenging with respect same in case previous hard X-ray solar imaging missions. In addition, we aim identify an effective optimization scheme for parametric STIX. Methods. This paper introduces a global search forward-fitting STIX and compares its effectiveness standard simplex-based used so far analysis Reuven...
Context. Reconstructing an image from noisy, sparsely sampled Fourier data is ill-posed inverse problem that occurs in a variety of subjects within science, including analysis for Very Long Baseline Interferometry (VLBI) and the Spectrometer/Telescope Imaging X-rays (STIX) with respect to solar observations. The need high-resolution, high-fidelity imaging fosters active development range novel algorithms different algorithmic settings. However, despite these ongoing, parallel developments,...
The Spectrometer/Telescope for Imaging X-rays (STIX) will study solar flares across the hard X-ray window provided by Solar Orbiter cluster. Similarly to Reuven Ramaty High Energy Spectroscopic Imager (RHESSI), STIX is a visibility-based imaging instrument that require Fourier-based image reconstruction methods. However, in this paper we show as RHESSI, count-based also possible STIX. Specifically, introduce and illustrate mathematical model mimics data formation process projection from...
Particle acceleration is a fundamental process arising in many astrophysical objects, including active galactic nuclei, black holes, neutron stars, gamma-ray bursts, accretion disks, solar and stellar coronae, planetary magnetospheres. Its ubiquity means energetic particles permeate the Universe influence conditions for emergence continuation of life. In our system, Sun most particle accelerator, its proximity makes it unique laboratory which to explore acceleration. However, despite...
Context. We present an analysis of a GOES M1.8 flare with excellent observational coverage in UV, EUV, and X-ray, including observations from the instruments IRIS, SDO AIA, Hinode/EIS, Hinode/XRT, Solar Orbiter Spectrometer/Telescope for Imaging X-rays (STIX). Hard X-ray emission is often observed at footpoints loops occasionally corona. In this flare, four nonthermal hard sources are seen. Aim. Our aim to understand why we can observe individual how characterize physical properties these...
Context. Regularized imaging spectroscopy was introduced for the construction of electron flux images at different energies from count visibilities recorded by Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI). In this work we seek to extend approach data Spectrometer/Telescope Imaging X-rays (STIX) on board Orbiter mission. Aims. Our aims are demonstrate feasibility regularized as a method analysis STIX data, and also show how such an can lead insights into physical processes...
Context. Extreme-ultraviolet (EUV) observations provide considerable insight into evolving physical conditions in the active solar atmosphere. For a prescribed density and temperature structure, it is straightforward to construct corresponding differential emission measure profile ξ ( Τ ), such that ) d T proportional emissivity from plasma range [ , + ]. Here we study inverse problem of obtaining valid set EUV spectral line intensities observed at pixel within image. Aims. Our goal...
Abstract CLEAN is an iterative deconvolution method for radio and hard-X-ray solar imaging. In a specific step of its pipeline, requires the convolution between idealized version instrumental point-spread function (PSF), map collecting point sources located at positions from where most flaring radiation emitted. This has highly heuristic motivations shape PSF, which depends on user’s choice, impacts reconstruction. study introduces user-independent release image reconstruction observations...
Aims: To provide the first demonstration of STIX Fourier-transform X-ray imaging using semi-calibrated (amplitude-only) visibility data acquired during Solar Orbiter's cruise phase. Methods: We use a parametric approach by which amplitudes are fitted means two non-linear optimization methods: fast meta-heuristic technique inspired social behavior, and Bayesian Monte Carlo sampling method, which, although slower, provides better quantification uncertainties. Results: When applied to set solar...
Space telescopes for solar hard X-ray imaging provide observations made of sampled Fourier components the incoming photon flux. The aim this study is to design an image reconstruction method relying on enhanced visibility interpolation in domain. % methods heading (mandatory) interpolation-based applied synthetic visibilities generated by means simulation software implemented within framework Spectrometer/Telescope Imaging X-rays (STIX) mission board Solar Orbiter. An application...
Models of particle acceleration in solar eruptive events suggest that roughly equal energy may go into accelerating electrons and ions. However, while previous X-ray spectroscopic imagers have transformed our understanding electron acceleration, only one resolved image γ-ray emission from accelerated ions has ever been produced. This paper outlines a new satellite instrument concept—the large imaging spectrometer for nuclei (LISSAN)—with the capability not to observe hundreds over its...
This talk shows that imaging-spectroscopy analyses from data recorded by the Spectrometer/Telescope for Imaging X-rays (STIX) on-board Solar Orbiter allow to disentangle two factors determine observed hard X-ray spectrum of a solar flare, i.e., density accelerated electrons and ambient target density. More specifically, we show, first time in quantitative way, case some peculiar events characterized significant coronal emission, number non-thermal flare is relatively small high rate such...
Abstract HXI on ASO-S and STIX onboard Solar Orbiter are the first simultaneously operating solar hard X-ray imaging spectrometers. ASO-S’s low Earth orbit Orbiter’s periodic displacement from Sun–Earth line enables multi-viewpoint spectroscopic analysis for time. Here, we demonstrate potential of this new capability by reporting results 3D triangulation sources in SOL2023-12-31T21:55 X5 flare. observed flare near east limb with an observer separation angle 18°. We triangulated brightest...
The Spectrometer/Telescope for Imaging X-rays (STIX) on-board the ESA Solar Orbiter mission retrieves coordinates of solar flare locations by means a specific sub-collimator, named Coarse Flare Locator (CFL). When occurs on Sun, emitted X-ray radiation casts shadow peculiar "H-shaped" tungsten grid over CFL detector. From measurements areas detector that are illuminated radiation, it is possible to retrieve $(x,y)$ location disk. In this paper, we train neural network dataset real...
In this work, we introduce a novel estimator of the predictive risk with Poisson data, when loss function is Kullback-Leibler divergence, in order to define regularization parameter's choice rule for Expectation Maximization (EM) algorithm. To aim, prove counterpart Stein's Lemma Gaussian variables, and from result derive proposed showing its analogies well-known Unbiased Risk Estimator valid quadratic loss. We that asymptotically unbiased increasing number measured counts, under certain...
AI-FLARES (Artificial Intelligence for the Analysis of Solar Flares Data) is a research project funded by Agenzia Spaziale Italiana and Istituto Nazionale di Astrofisica within framework ``Attivit\`a Studio per la Comunit\`a Scientifica Sole, Sistema Solare ed Esopianeti'' program. The topic addressed this was development use computational methods analysis remote sensing space data associated to solar flare emission. This paper overviews main results obtained project, with specific focus on...