Water Cherenkov technology in gamma-ray astrophysics Sinnis, Gus
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2010, Letnik:
623, Številka:
1
Journal Article
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Traditional extensive air shower (EAS) arrays consisted of a sparse array of plastic scintillation counters dispersed over a large area. Typically 1–2% of the enclosed detector area was sensitive to ...the passage of electromagnetic particles. The resulting telescopes had energy thresholds above 100TeV and did not detect any astrophysical sources of gamma rays. The advent of water Cherenkov technology allowed for the construction of an EAS array that was fully active over 100% of the enclosed area. This lead to the dramatic reduction of the energy threshold of such instruments (near 1TeV) and the subsequent detection of sources of gamma rays. The Milagro detector in the Jemez Mountains of northern New Mexico was the first such instrument built. Milagro discovered the Galactic diffuse emission at 10TeV and at least 3 new sources of TeV gamma rays. These observations have established the role of all-sky instruments in the Tera-Volt energy band. These instruments are uniquely sensitive to transient phenomena, such as gamma-ray bursts and flaring active galaxies. A next generation water Cherenkov detector, HAWC (for High Altitude Water Cherenkov) has now been proposed. In this paper I will discuss the water Cherenkov technique and its use in gamma-ray astrophysics. I will touch upon the physics observations that an instrument such as HAWC can enable and elaborate on the technological advances needed to support further work in this area.
The High Altitude Water Cherenkov (HAWC) Observatory is a wide-field-of-view gamma-ray observatory that is optimized to detect gamma rays between 300 GeV and several hundred TeV. The HAWC ...Collaboration recently released their third source catalog (3HWC), which contains 65 sources. One of these sources, the ultra-high-energy gamma-ray source 3HWC J1908+063, may exhibit a hardening of the spectral index at the highest energies (above 56 TeV). At least two populations of particles are needed to satisfactorily explain the highest energy emission. This second component could be leptonic or hadronic in origin. If it is hadronic in origin, it would imply the presence of protons with energies up to ~1 PeV near the source. We have searched other 3HWC sources for the presence of this spectral hardening feature. If observed, this would imply that the sources could make good PeVatron candidates.
The Ultra-High-Energy Source MGRO J1908+06 Malone, Kelly; Abeysekara, Anushka Udara; Albert, Andrea ...
Pos : proceedings of science,
07/2021, Letnik:
395
Journal Article
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Odprti dostop
The TeV gamma-ray source MGRO J1908+06 is one of the highest-energy sources known, with observed emission by the High Altitude Water Cherenkov (HAWC) Observatory extending well past 100 TeV. The ...source exhibits both energy-dependent morphology and a spatially-dependent spectral index. The emission is likely to be dominantly leptonic, and associated with the radio-quiet PSR J1907+0602. However, one-population models do not describe the data well; a second particle population is needed to explain the shape of the spectral energy distribution at the highest energies. This component can be well-described by either leptonic or hadronic hypotheses. We discuss this feature and implications for detection by multi-wavelength and multi-messenger experiments.
Very-high-energy astronomy studies the Universe at energies between 30 GeV
and 100 TeV. The past decade has seen enormous progress in this field. There
are now at least seven known sources of VHE ...photons. By studying these objects
in the VHE regime one can begin to understand the environments surrounding
these objects, and how particle acceleration is realized in nature. In addition
the photon beams from the extragalactic gamma-ray sources can be used to study
the electromagnetic fields in the intervening space. This recent progress can
be traced to the development of a new class of detector with the ability to
differentiate between air showers produced by gamma rays and those produced by
the much more numerous hadronic cosmic-ray background. Much more sensitive
instruments are currently in the design phase and two new types of instruments
are beginning to take data. In this paper we will discuss the physics of these
sources and describe the existing and planned detectors.
Very-high-energy astronomy studies the Universe at energies between 30 GeV and 100 TeV. The past decade has seen enormous progress in this field. There are now at least seven known sources of VHE ...photons. By studying these objects in the VHE regime one can begin to understand the environments surrounding these objects, and how particle acceleration is realized in nature. In addition the photon beams from the extragalactic gamma-ray sources can be used to study the electromagnetic fields in the intervening space. This recent progress can be traced to the development of a new class of detector with the ability to differentiate between air showers produced by gamma rays and those produced by the much more numerous hadronic cosmic-ray background. Much more sensitive instruments are currently in the design phase and two new types of instruments are beginning to take data. In this paper we will discuss the physics of these sources and describe the existing and planned detectors.
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