A search for UHE gamma-rays from 13 candidate point sources observable in the northern hemisphere (the Crab Nebula and Pulsar, Cygnus X-3, Hercules X-1, Geminga and others) has been performed by the EAS-TOP array during four years of operation since January 1989 to December 1993, at different energy thresholds (E(0) = 30-300 TeV). DC, periodic and sporadic emissions have been studied, and no evidence for significant excesses has been found from any of these searches. The derived 90% c.l. upper limits to the d.c. flux, for a source culminating at the zenith such as Cygnus X-3, are Phi(E > 230 TeV) < 2 x 10(-14) cm(-2) s(-1), Phi(E > 90 TeV) < 4.1 x 10(-14) cm(-2) s(-1) and Phi(E > 25 TeV) < 1.9 x 10(-13) cm(-2) s(-1). The excess from the Crab Nebula of February 23, 1989, as reported by the EAS-TOP, Baksan and KGF arrays, remains the only sporadic excess detected with statistically significant confidence level (probability of background imitation approximate to 10(-5)).
Results On Candidate Uhe Gamma-ray Sources By the Eas-top Array (1989-1993) / M., A., B., A., P., A., F., A., L., B., A. C., F., C., C., A., C., A., C., G., C., D'ETTORRE PIAZZOLI, B., G., D., W., F., P., G., P. L., G., Iacovacci, M., G., M., C., M., G., N., L., R., et al.. - In: ASTROPARTICLE PHYSICS. - ISSN 0927-6505. - STAMPA. - 3:(1995), pp. 1-15. [10.1016/0927-6505(94)00026-Y]
Results On Candidate Uhe Gamma-ray Sources By the Eas-top Array (1989-1993)
D'ETTORRE PIAZZOLI, BENEDETTO;IACOVACCI, MICHELE;
1995
Abstract
A search for UHE gamma-rays from 13 candidate point sources observable in the northern hemisphere (the Crab Nebula and Pulsar, Cygnus X-3, Hercules X-1, Geminga and others) has been performed by the EAS-TOP array during four years of operation since January 1989 to December 1993, at different energy thresholds (E(0) = 30-300 TeV). DC, periodic and sporadic emissions have been studied, and no evidence for significant excesses has been found from any of these searches. The derived 90% c.l. upper limits to the d.c. flux, for a source culminating at the zenith such as Cygnus X-3, are Phi(E > 230 TeV) < 2 x 10(-14) cm(-2) s(-1), Phi(E > 90 TeV) < 4.1 x 10(-14) cm(-2) s(-1) and Phi(E > 25 TeV) < 1.9 x 10(-13) cm(-2) s(-1). The excess from the Crab Nebula of February 23, 1989, as reported by the EAS-TOP, Baksan and KGF arrays, remains the only sporadic excess detected with statistically significant confidence level (probability of background imitation approximate to 10(-5)).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
