Observation of EGRET gamma-ray sources by an Extensive Air Shower experiment

Abstract

Abstract. Ultra-high-energy (E > 100 TeV) Extensive Air Showers (EASs) have been monitored for a period of five years (1997)(1998)(1999)(2000)(2001)(2002)(2003), using a small array of scintillator detectors in Tehran, Iran. The data have been analyzed taking into account the dependence of source counts on zenith angle. During a calendar year different sources come into the field of view of the detector at varying zenith angles. Because of varying thickness of the overlaying atmosphere, the shower count rate is extremely dependent on zenith angle, which has been carefully analyzed over time (Bahmanabadi et al. 2002, Exp. Astron., 13, 39). High energy gamma-ray sources from the EGRET third catalogue where observed and the data were analyzed using an excess method. Upper limits were obtained for a number of EGRET sources, including 6 AGNs or probably AGNs and 4 unidentified sources.

Galactic Anisotropy of Cosmic Ray Intensity Observed by an Air Shower Experiment

“…where f 0 is the zenith angle of the cosmic ray and a the difference between the azimuth angle of the direction of motion and of the cosmic ray that is, a = A 1 -A 2 , where A 1 and A 2 are obtained from the equations (4) Amplitude ( Table 1. (cosf 0 ) n sinf 0 df 0 with n = 6; (Khakian et al 2005). By this distribution, we calculated the mean cosf 0 value which is 0.93.…”

“…The curve is the best fit to Eqn. (4) with the coefficients as listed in Table 1. (cosf 0 ) n sinf 0 df 0 with n = 6; (Khakian et al 2005). By this distribution, we calculated the mean cosf 0 value which is 0.93.…”

Study of the extensive air shower mass sensitive parameters in prototype of ALBORZ array

“…890 gcm À2 ). It is a small array and contains 5 plastic scintillators (50 Â 50 Â 2cm 3 ) which has been used to investigate anisotropy of cosmic rays arrival directions (Bahmanabadi et al, 2003), finding gamma ray sources (Khakian Ghomi et al, 2005) and atmosphere thickness effect on EASs (Khakian Ghomi et al, 2007). This array will be developed and located at ALBORZ Mountain (2500 m a.s.l.)…”

Astrophysics in 2005

“…There is also an extensive air shower array in Tehran (Khakian Ghomi et al 2005), for which we think we are interested only in the departure directions.…”

“…• Are the arrival directions random or clustered (Abbasi et al 2005;Amenomori et al 2005, a result from an air shower array in Tibet, suggesting the heliosphere as a source)? There is also an extensive air shower array in Tehran (Khakian Ghomi et al 2005), for which we think we are interested only in the departure directions.…”