Evidence for time variability of PeV energy flux from Cygnus X - 3 - Ooty observations during the period 1984-1987

Abstract

view Abstract Citations (8) References (21) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Evidence for Time Variability of PeV Energy Flux from Cygnus X-3: Ooty Observations during the Period 1984--1987 Tonwar, S. C. ; Gupta, S. K. ; Rajeev, M. R. ; Sreekantan, B. V. ; Srivatsan, R. Abstract Results are presented of an investigation of the observed rate of showers arriving from the direction of Cyg X - 3 as a function of time from data collected with the EAS array at Ooty during June 1984-May 1987. A total of 83 showers were observed in the source bin during the period March 2-April 12, 1986 against an expected number of 56.5. The chance probability for observing such an excess during a 13-wk time interval, which covers all observations of similar enhancements, is estimated to be 1 percent. Ooty observations therefore support earlier suggestions on variability in the PeV flux from Cyg X - 3 over a time scale of a few weeks. A study of the observed rate of 'doubles' in Ooty data shows that during April 5-21, 1986 the number of 'doubles' observed from the direction of Cyg X - 3 was 10 compared to the expected number of 1.5. Simulations carried out using the observed shower rate and its zenith angle dependence give the chance probability for this excess to be 0.008. Ooty observations therefore suggest that a part of the emission at PeV energies was in the form of short-duration bursts which lasted only a few tens of minutes. Publication: The Astrophysical Journal Pub Date: May 1992 DOI: 10.1086/171277 Bibcode: 1992ApJ...390..273T Keywords: Binary Stars; Cosmic Ray Showers; Gamma Ray Astronomy; Radiant Flux Density; X Ray Sources; Annual Variations; Energy Distribution; Temporal Distribution; Time Series Analysis; Astrophysics; GAMMA RAYS: OBSERVATIONS; STARS: INDIVIDUAL CONSTELLATION NAME: CYGNUS X-3 full text sources ADS | data products SIMBAD (1)