Analyzing the High Energy Activity of Candidate Neutrino Emitter Blazars to Constrain their Observability through Deep Sea/Ice Cherenkov Telescopes

• Main Author: SHARMA, ANKUR
• Other Authors: Marinelli, Antonio
• Format: Text
• Language: Italian
• Published: Pisa University 2020
• Subjects: FIS/01; Orca; Sea ice
• Online Access: http://etd.adm.unipi.it/theses/available/etd-04082020-081434/

This PhD dissertation tackles the question of hadronic emission from the jets of blazars. Neutrinos are produced in the interactions of protons and neutrons with ambient photons and hence are a tell-tale sign of proton acceleration in the jets of AGN. The thesis focuses on analyzing the high energy activity of a sample of blazars selected for their spatial coincidence with candidate astrophysical neutrino events, and the characterization of their activity in high energy gamma-rays to understand their neutrino emission potential. Code has been developed to check for spatial and/or temporal overlap between blazars sampled from the Fermi-LAT 3FGL and 3FHL catalogs, and muonic neutrino events from IceCube with a high probability of being astrophysical in origin. Long-term light-curves of the blazars are obtained using Fermi-LAT data to identify their prominent flares. Their gamma-ray duty cycles and luminosities are also calculated, and the gamma-ray activity is related with neutrino emission using a one-zone lepto-hadronic model from Petropoulou et al. 2015. With this correlation, we are able to identify the minimum flare duration in gamma required to observe a neutrino in the km^3 Cherenkov telescopes around the world like IceCube and KM3NeT. The broad-band SEDs of a select few blazars are also analyzed and their gamma-ray SEDs compared during the flaring and quiescent periods. A portion of the thesis deals with the time calibration of the two detector units of KM3NeT experiment (ARCA & ORCA) using atmospheric muons, and the data validation of 2 lines of KM3NeT/ARCA. As part of the calibration work, an approach is developed for inter-DOM time calibration that is independent of Monte Carlo and converges faster than the Monte Carlo-based strategy. It was tested on both KM3NeT/ARCA and KM3NeT/ORCA data with initial success. The data validation study involves the analysis of the ToT signals and PMT rates in KM3NeT/ARCA data and their comparison with Monte Carlo. Time-dependent and differential sensitivity studies ...