Search Results (4)

It has long been debated whether gamma-ray bursts (GRBs) could serve as potential sources of ultra-high-energy cosmic rays (UHECRs). In this study, we consider GRBs as sources of UHECR injection with an injection index of $\alpha =2$ and propagate them through the extragalactic magnetic field within the framework of CRPropa 3. The baryon loading factor $f_{CR}$ is taken into account to quantify the rate of UHECR energy injection. In the benchmark case with a jet opening angle of ${\theta }_j=1$ and $f_{CR}=1$, we find that both high- and low-luminosity populations contribute to less than 10% of the UHECR spectrum. The most constrained scenario suggests $f_{CR}\le 15$, indicating that GRBs are less efficient in producing the all-sky UHECR intensity. The high-energy diffuse neutrinos and gamma rays resulting from interactions between UHECRs from GRBs and extragalactic background photons do not dominate the observations of Fermi-LAT or IceCube. Full article

The development of multimessenger astrophysics allows us to probe various background particles from the distant early universe. Up to now, much effort has been made researching the emission and radiation of diverse steady or transient astrophysical sources. We review the potential accelerating, escaping, propagating, and radiation process of high-energy particles under specific circumstances for regular astrophysical sources and briefly discuss the underlying contribution from their emissions to the intensity of ultrahigh-energy cosmic ray, TeV-PeV cosmic neutrino, and the diffuse gamma-ray background, aiming to find a possible common origin. Full article

The ICARUS detector will search for LSND-like neutrino oscillations exposed at shallow depths to the FNAL BNB beam, acting as the far detector in the short-baseline neutrino (SBN) program. Cosmic background rejection is particularly important for the ICARUS detector due to its larger size and distance from neutrino production compared to the near detector SBND. In ICARUS, the neutrino signal over the cosmic background ratio is 40 times more unfavorable compared to SBND, partly due to an out-of-spill cosmic rate that is over three times higher. In this paper, we will illustrate techniques for reducing cosmogenic backgrounds in the ICARUS detector with initial commissioning data. Full article

The Pierre Auger Observatory is the world’s largest operating detection system for the observation of ultra high energy cosmic rays (UHECRs), with energies above ${10}^{17}$ eV. The detector allows detailed measurements of the energy spectrum, mass composition and arrival directions of primary cosmic rays in the energy range above ${10}^{17}$ eV. The data collected at the Auger Observatory over the last decade show the suppression of the cosmic ray flux at energies above $4\times {10}^{19}$ eV. However, it is still unclear if this suppression is caused by the energy limitation of their sources or by the Greisen–Zatsepin–Kuzmin (GZK) cut-off. In such a case, UHECRs would interact with the microwave background (CMB), so that particles traveling long intergalactic distances could not have energies greater than $5\times {10}^{19}$ eV. The other puzzle is the origin of UHECRs. Some clues can be drawn from studying the distribution of their arrival directions. The recently observed dipole anisotropy has an orientation that indicates an extragalactic origin of UHECRs. The Auger surface detector array is also sensitive to showers due to ultra high energy neutrinos of all flavors and photons, and recent neutrino and photon limits provided by the Auger Observatory can constrain models of the cosmogenic neutrino production and exotic scenarios of the UHECRs origin, such as the decays of super heavy, non-standard-model particles. In this paper, the recent results on measurements of the energy spectrum, mass composition and arrival directions of cosmic rays, as well as future prospects are presented. Full article