Nuvens moleculares como fontes multi-mensageiras: raios cósmicos, raios gama e neutrinos.

Abstract

Molecular clouds are interstellar regions formed by gas and dust and can be studied as possible multi-messenger sources, emitting cosmic rays, gamma rays, and neutrinos. Cosmic rays are relativistic charged particles, composed mainly of atomic nuclei, such as protons and alpha particles, and electrons. These particles, during their propagation through the interstellar medium, can interact with molecular clouds, causing various physicochemical changes, such as gas and grain heating and molecular formation and destruction. The interaction of cosmic rays with molecular clouds generates the ionization of interstellar gas and increases the heating rate, which can alter the stability of the cloud and facilitate or inhibit gravitational collapse, a crucial process for the birth of new stars. Furthermore, the interaction of cosmic rays with molecular clouds produces hadronic, electromagnetic, and muonic secondary particles via different physical processes. This work aims to investigate the physical mechanisms of cosmic-ray interaction, of different chemical compositions and energies, with a typical molecular cloud (mass 5400 M⊙ containing H and C atoms, size of ∼ 4.8 pc and average number density ∼ 300 cm−3) using the Geant4 Monte Carlo simulation method. Thus, the energy deposited in different cloud layers and the spectra of hadrons, gamma rays, and neutrinos that emerge from the cloud are investigated. Many molecular clouds are relatively close to supernova remnants, which are intense sources of cosmic rays. The Perseus molecular cloud may provide an ideal environment to study how these violent events impact nearby clouds, enriching the interstellar medium with heavy elements and energy. In this way, we also investigated the interaction of cosmic rays with the Perseus molecular cloud, which is a star-forming region located in the constellation Perseus, approximately 1000 light-years from Earth. It is a large cloud of interstellar gas and dust, filled with dense, cold regions where new stars are forming.