741 research outputs found
The TeV Energy Spectrum of Mrk 421 Measured in A High Flaring State
The BL Lac object (blazar) Mrk 421 was observed during its outburst in April
2004 with the Whipple 10 m telescope for a total of about 24.5 hours. The
measured gamma-ray rate varied substantially over the range from 4 to 10
gamma's/min and eventually exceeded the steady gamma-ray rate of the Crab
Nebula (standard candle) by a factor of 3. The overall significance of the
gamma-ray signal exceeded 70 sigma and the total number of excess events was
more than 10,000. The signal light curve does not show any particular
variability pattern. This unique Mrk 421 outburst enabled the measurement of a
high quality spectrum of very high-energy gamma rays in a high state of
emission. This spectrum is a power-law and it extends beyond 10 TeV.Comment: 4 pages, 5 figures, Proc. 30th International Cosmic Ray Conference,
Merida, Mexico, 200
ALTAI: Computational code for the simulations of TeV air showers as observed with the ground-based imaging atmospheric Cherenkov telescopes
Ground-based atmospheric Cherenkov telescopes are proven to be effective
instruments for observations of very high energy (VHE) gamma-radiation from
celestial objects. For effective use of such technique one needs detailed Monte
Carlo simulations of gamma-ray- and proton/nuclei-induced air showers in Earth
atmosphere. Here we discuss in detail the algorithms used in the numerical code
ALTAI developed particularly for the simulations of Cherenkov light emission
from air showers of energy below 50 TeV. The specific scheme of sampling the
charged particle transport in the atmosphere allows the performance of very
fast and accurate simulations used for interpretation of the VHE gamma-ray
observations.Comment: 11 pages, 4 figures, Nuclear Instruments & Methods in Physics
Research (Section A), in pres
Monte Carlo studies on the sensitivity of the HEGRA imaging atmospheric Cerenkov telescope system in observations of extended gamma-ray sources
In this paper, we present the results of Monte Carlo simulations of
atmospheric showers induced by diffuse gamma rays as detected by the
high-energy gamma ray astronomy (HEGRA) system of five imaging atmospheric
Cerenkov telescopes (IACTs). We have investigated the sensitivity of
observations on extended gamma ray emission over the entire field of view of
the instrument. We discuss a technique to search for extended gamma ray sources
within the field of view of the instrument. We give estimates for HEGRA
sensitivity of observations on extended TeV gamma ray sources.Comment: 21 pages, 7 figures, accepted for publication in "Journal of Physics
G: Nuclear and Particle Physics
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