Speaker
Description
Sources of ultra-high energy cosmic rays (UHECRs) are still not clear. UHECRs encompass the most energetic particles detected by ground experiments. Their sources could be neutron stars ($l \sim 10$ km), AGNs ($l \sim 10$ kpc) and even Galaxy clusters ($l \sim 1$ Mpc). It is well accepted that the production mechanisms for cosmic rays from many sources, bellow the Greisen-Zatsepin-Kuzmin (GZK) cuttoff, are the Fermi mechanism, diffuse shock acceleration, magnetic reconnection, among others. In particular, UHECRs propagate with energies beyond GZK ($> 10^{19}$ eV). Ultra high center-of-mass energies for particle collisions near coalescent binary systems of neutron stars (NSs) and black holes (BHs) could explain part of the UHECR source conumdrum. Therefore, it is natural to look at UHECRs and their byproducts from binary systems. Here we use perspectives of the so called Penrose Process to calculate the possible particle energy upper limit at the border of binary systems. In the present approach, the maximum energy comes from a combination of the Wald mechanism and the Bañados-Silk-West (BSW) effect. Here, details on the BSW effect are plentifully discussed as a collisional phenomenon from where the form factor of the center-of-mass energy of particles comes.
