Gravitational waves search for generic transient of intermediate duration in future interferometes network using coherentWave Burst algorithm

Searches for generic transient Gravitational Waves (GW) target the widest possible range of different astrophysical sources, using no or minimal assumption on the morphology of the signal; in particular different astrophysical phenomena are foreseen to emit GW signals with long duration (by few sec. to hundreds of sec.), among those: fallback, newborn neutron , accretion disk instabilities, non axisymmetric deformation in magnetars. Coherent Wave Burst (cWB) is the flagship algorithm, in the LIGO- Virgo collaboration, used for the generic transient analysis without assumption morphology or arrival direction of GW signal. This project contributes to improve and optimize cWB algorithm for long duration generic gravitational waves search in the LHV (LIGO-Virgo) interferometers network. In particular the project aims to test possible algorithm configurations for next data taking of LHV (O4 is foreseen to start by the beginning of the next year), through a reanalysis and simulations campaign of public data of last data taking (O3b - November 2019 to March 2020). Specifically the project reanalyses the O3b data giving attention to the efficiency of the algorithm in reconstructing the signals. The first purpose of the project was developing codes and analysis to characterize the parameters of the signals like frequency, length etc. Also the capability of the algorithm in reassembling correctly the injected signal, considering the number of segments in which is divided the trigger obtained by the pipeline have been held specially into account, since this parameter qualifies the effectiveness of the algorithm in regaining the signal through clustering process. Statistical studies of this characteristic have been taken into attention, studying the segmentation process among different morphologies of gravitiational waves signal expected for astrophysical processes. The waveforms have been chosen in order to cover a wide spectrum of morphologies, duration and frequency. Furthermore, the network with expected sensitivity for post-O4 data taking has been studied, considering a scaled strain sensitivity curve of the detectors obtained from the O3b data, and performing injection of the same Gravitational Wave signals used in O3b analysis. In particular efficiency and background analysis have been taken into account, especially in LHV network configuration due to the additional noisy behavior of the Virgo interferometer. Two different configurations of the algorithm have been studied in order to classify properly the case of non coaligned three interferometer detector networks, as LHV. Finally in this project the test of the machine learning algorithm already introduced in other cWB searches will be performed for the long search. This algorithm is supposed to help us in noise-signal discharge analysis, distinguishing the Gravitational Waves signals from the noise background and it has already been used for other research. In particular different astrophysical phenomena are foreseen to emit GW signals with long duration (by few sec. to hundreds of sec.) .