arXiv subjects

I. Viale

Publications and source records attributed to I. Viale.

3 recordsLinked to original sources

arXiv2025

Deep Learning-Based Stereoscopic Event Reconstruction for CTAO using CTLearn

The Cherenkov Telescope Array Observatory (CTAO), a next-generation ground-based gamma-ray observatory, will be composed of two arrays of multiple imaging atmospheric Cherenkov telescopes (IACTs) located in both the Northern and Southern Hemispheres. Its goal is to enhance the sensitivity of current instruments by a factor of five to ten over an energy range from 20 GeV to over 300 TeV. IACT arrays are used to probe the very-high-energy (VHE) gamma-ray sky, operating by simultaneously observing air showers triggered by the interaction of VHE gamma rays and cosmic rays with the atmosphere. Cherenkov photons produced by these showers create a stereoscopic record of the event. By reconstructing the event using machine learning techniques, the properties of the originating VHE particle-including its type, energy, and incoming direction-can be determined. In this contribution, we present a fully deep-learning-driven approach to reconstruct simulated, stereoscopic IACT events using CTLearn. CTLearn is a package designed for loading and manipulating IACT data and for running deep learning models with pixel-wise camera data as input.

astro-ph.HE↗

arXiv2025

Towards a TeV blazar sequence and its physical interpretation

Blazars, a highly energetic subclass of jetted active galactic nuclei, show a broad band spectral energy distribution (SED) with two bumps, resulting from non-thermal jet emission. In 1998, an anticorrelation between the SED luminosity and the peaks frequency was found, later confirmed in 2017, called the blazar sequence. Its origin is still unclear. This work is part of a broader effort aiming at giving a physical interpretation to the blazar sequence, by modeling the sources emission in a Synchrotron Self Compton framework, concentrating only on TeV-detected blazars of BL Lac type. Unlike the original sequence, sources were binned by synchrotron peak frequency. The SED of one representative source is modeled for each bin, using data from average activity state to ensure consistency. Here, we focus on the study of one of the selected representative sources, PKS 2155-304, a high-energy-peaked BL Lac, showing the performed data selection and preliminary modeling results.

astro-ph.HE↗

arXiv2022

A catalog of new Blazar candidates with Open Universe by High School students

Blazars are active galactic nuclei whose ultra-relativistic jets are coaligned with the observer direction. They emit throughout the whole e.m. spectrum, from radio waves to VHE gamma rays. Not all blazars are discovered. In this work, we propose a catalog of 54 new candidates based on the association of HE gamma ray emission and radio, X-ray an optical signatures. The relevance of this work is also that it was performed by four high school students from the Liceo Scientifico Statale Ugo Morin in Venice, Italy using the open-source platform Open Universe, in collaboration with the University of Padova. The framework of the activity is the Italian MIUR PCTO programme. The success of this citizen-science experience and results are hereafter reported and discussed.

astro-ph.HE↗