The Arrival Direction Distribution of Extremely High Energy Cosmic Rays Observed by AGASA

Study of the arrival direction distribution plays a key role in finding sources of the Extremely High Energy Cosmic Rays (EHECR). Greisen-Zatsepin-Kuz\u27min (GZK) mechanism limits the propagation of EHE cosmic rays significantly and only nearby sources can contribute to the local EHECR flux. Furthermore EHECRs travel intergalactic spaces almost linearly. Hence, we expect they can be traced back to their sources. Here we report a small-sacle anisotropy of the arrival direction distribution of EHECRs observed by AGASA above 1019eV . This result strongly suggests the existence of point sources of EHECRs

Chemical Composition of Ultra-High Energy Cosmic Rays Observed by AGASA

We have observed ultra-high energy cosmic rays above the Greisen-Zatsepin-Kuz\u27min cut-off energy by Akeno Giant Air Shower Array. Their chemical composition is a key discriminator of origin models. In the present work, we estimate the average composition by an analysis of muons in air showers with AIRES+QGSJET simulation. The data matches the prediction for light hadron primaries and no indication has been found for a gamma-ray dominance