Artículo
Very high-energy γ-ray observations of the Crab nebula and other potential sources with the GRAAL experiment
Autor/es | Arqueros, Fernando
Ballestrín, Jesús Berenguel, Manuel Borque, D.M. Camacho, Eduardo F. Díaz, M. Gebauer, H.-J. Enríquez, R. Plaga, R. |
Departamento | Universidad de Sevilla. Departamento de Ingeniería de Sistemas y Automática |
Fecha de publicación | 2002 |
Fecha de depósito | 2020-03-04 |
Publicado en |
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Resumen | The “γ-ray astronomy at Almeria” (GRAAL) experiment uses 63 heliostat-mirrors with a total mirror area of ≈2500 m2 from the CESA-1 field at the “Plataforma Solar de Almeria” to collect Cherenkov light from air showers. The ... The “γ-ray astronomy at Almeria” (GRAAL) experiment uses 63 heliostat-mirrors with a total mirror area of ≈2500 m2 from the CESA-1 field at the “Plataforma Solar de Almeria” to collect Cherenkov light from air showers. The detector is located in a central solar tower and detects photon-induced showers with an energy threshold of 250±110 GeV and an asymptotic effective detection area of about 15 000 m2. A comparison between the results of detailed Monte-Carlo simulations and data is presented. Data sets taken in the period September 1999–September 2000 in the direction of the Crab pulsar, the active galaxy 3C 454.3, the unidentified γ-ray source 3EG J1835+59 and a “pseudosource” were analyzed for high energy γ-ray emission. Evidence for a γ-ray flux from the Crab pulsar with an integral flux of 2.2±0.4 above threshold and a significance of 4.5σ in a total measuring time of 7 h and 10 min on source was found. No evidence for emission from the other sources was found. Some difficulties with the use of heliostat fields for γ-ray astronomy are pointed out. In particular the effect of field-of-view restricted to the central part of a detected air shower on the lateral distribution and timing properties of Cherenkov light are discussed. Upon restriction the spread of the timing front of proton-induced showers sharply decreases and the reconstructed direction becomes biased towards the pointing direction. This is shown to make efficient γ-hadron separation difficult. |
Cita | Arqueros, F., Ballestrín, J., Berenguel, M., Borque, D.M., Fernández Camacho, E., Díaz, M.,...,Plaga, R. (2002). Very high-energy γ-ray observations of the Crab nebula and other potential sources with the GRAAL experiment. Astroparticle Physics, 17 (.3), 293-318. |
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