Abstract
The High-Altitude Water Cherenkov (HAWC) TeV gamma–ray Observatory in Mexico is ready to search and study gamma-ray emission regions, extremely high-energy cosmic-ray sources, and to identify transient phenomena. With a better Gamma/Hadron rejection method than other similar experiments, it will play a key role in triggering multi–wavelength and multi–messenger studies of active galaxies (AGN), gamma-ray bursts (GRB), supernova remnants (SNR), pulsar wind nebulae (PWN), Galactic Plane Sources, and Cosmic Ray Anisotropies. It has an instantaneous field-of-view of ∼2 str, equivalent to 15% of the whole sky and continuous operation (24 hours per day). The results obtained by HAWC–111 (111 detectors in operation) were presented on the proceedings of the International Cosmic Ray Conference 2015 and in [1]. The results obtained by HAWC–300 (full operation) are now under analysis and will be published in forthcoming papers starting in 2017 (see preliminary results on http://www.hawc-observatory.org/news/). Here we present the HAWC contributions on cosmic ray astrophysics via anisotropies studies, summarizing the HAWC detector and its upgrading by the installation of “outriggers”.
Highlights
When high-energy particles or photons, referred to as primaries, with E > Ec enter the Earth’s atmosphere (Z=7) at an altitude of ∼30 km, an extensive air shower (EAS) is induced
If a gamma ray primary hits a nucleus in the Earth’s atmosphere, an electron-positron pair is produced by Coulomb interaction
The radiation length, X0, is the distance over which a high energy electron decreases its energy through bremsstrahlung to 1/e
Summary
When high-energy particles or photons, referred to as primaries, with E > Ec (where Ec ∼600 MeV /Z Ec is the critical energy and Z the atomic number) enter the Earth’s atmosphere (Z=7) at an altitude of ∼30 km, an extensive air shower (EAS) is induced. If a gamma ray primary hits a nucleus in the Earth’s atmosphere, an electron-positron pair is produced by Coulomb interaction. These electrically charged particles, interact with other atmospheric nucleus producing secondary gamma rays via bremsstrahlung radiation (e± + N −→ e± + N + γ ). While IACT’s are excellent telescopes for high resolution observations, Water Cerenkov Detectrs c The Authors, published by EDP Sciences. (WCD) are excellent as monitoring instruments for transients, AGNs, and large scale structures
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