In the last decade, new classes of sources (fast radio burst, binary neutron star mergers, ...) have been discovered thanks to progress in photon astronomy at all wavelengths. With the advent of multimessenger astronomy, we were able to scrutinize them with cosmic rays, neutrinos, photons and gravitational waves, opening a new era in the field of high-energy astrophysics.

The first part of my talk will be dedicated to the study of the high-energy and ultra high-energy neutrinos. Since the discovery in 2013 by IceCube of a diffuse neutrino flux, two major questions have been raised: what are the sources of this diffuse flux, and can we detect neutrinos at higher energies (> PeV). To help answering these questions, I will first consider them from the theoretical perspective and  present a model of high-energy neutrino emissions from neutron star mergers.

Then I will move to the experimental perspective and present the concepts of the radio detection of extensive air showers induced by ultra high-energy neutrinos. I will introduce different planned experiments that will use this technique. Then, I will focus on a study of a detector optimisation, and a detailed analysis of the signal characteristics with the goal to develop a reconstruction procedure for this new generation of detectors.

If time allows for it, the second part of this talk will be dedicated to the study of the fast radio bursts. These brief, coherent and numerous radio pulses, have not been identified yet and many experimental unknowns remain. I will start by detailing a source model that focus on the question of the pulses rates. Finally, I will present an observational program conducted with the NenuFAR instrument, located in the Nançay Radio Astronomy Station (France), dedicated to the detection and the characterisation of FRBs at low frequency (<100MHz).