Finding the gamma-ray counterparts of gravitational wave events with Fermi LAT

The purpose of this thesis is to focus on the collaboration between the Laser Interferometer Gravitational-Wave Observatory (LIGO) and the Fermi Gamma-ray Space Telescope, in particular its main instrument, the Large Area Telescope (LAT), that is continuously scanning the gamma-ray sky in the range between 30 MeV and more than 300 GeV. This cooperation has started since the recent detection of two gravitational-wave (GW) signals by LIGO, on September and December of the last year respectively. "Banana" sky probability maps, provided by LIGO to Fermi Collaboration, contain the probability that the detected GW source is located at any given direction of the sky. Our aim consists in developing a tool that matches the GW probability values to the positions of detected gamma-ray sources: it will enable the Flare Advocate on duty to immediately report a likely gamma-ray counterpart of the GW event and to alert the world-wide community of observatories. Follow-up campaigns are going to investigate possible connections between gravitational waves and electromagnetic emission in a wide wavelength range. HEALPix, one of the methods of sphere pixelation mostly used for dealing with large amounts of astronomical data, has played an important role in the elaboration of the tool, providing functions that are useful to manipulate directions of the sky and to visualize sky maps. The result is a basic simple code written in Python, that is going to be extended with additional features, in order to study, for instance, neutrinos emission from GW sources as well.