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

Tonwar, S. C.; Gupta, Sunil; Rajeev, M. R.; Sreekantan, B. V.; Srivatsan, R.

doi:10.1086/171277

Cited by 7 publications

(5 citation statements)

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“…The events were found to be modulated with the 4.8 hr period. Excesses were also seen during this interval at the Baksan (Alexeenko et al 1987), Ooty (Tonwar et al 1992), and Akeno (Teshima et al 1990) arrays. The Ooty group examined their data to search for burst activity on shorter time scales by looking at the weekly occurrence of two events within 15 minutes of each other.…”

Section: Status Of Ultra-high-energy 7-ray Observations 885 23 Obsementioning

confidence: 83%

“…Surprisingly, the emission occurred near orbital phase 0. Two days later, the Ooty array observed six showers from the direction of Cygnus X-3 during a 40 minute interval (Tonwar et al 1992). This was way above their average rate which was about one per day, and the orbital phase of emission was between 0.0 and 0.15.…”

Section: Status Of Ultra-high-energy 7-ray Observations 885 23 Obsementioning

confidence: 99%

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The Status of Ultra-High-Energy Gamma-Ray Observations

Protheroe

1994

International Astronomical Union Colloquium

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In 1983 Samorski and Stamm found evidence of ultra-high-energy (UHE) gamma-ray emission from Cygnus X-3 in archival data from the Kiel air shower array. The emission appeared to be emitted only at one phase in the binary orbit. The Kiel array was sensitive to air showers generated by particles with energies above 3 X 10 15 eV. Their discovery led to searches in archival data from other arrays for evidence of UHE emission from Cygnus X-3 and other potential sources in the Galaxy, and to the construction of new air shower arrays dedicated to UHE astronomy.In the mid 1980s many groups around the world claimed detections of Cygnus X-3, Hercules X-l, Vela X-l, and other objects. Cygnus X-3 is strongly variable at all wavelengths, and so it would be surprising if this variability did not extend to UHE gamma-rays also. This indeed appeared to be the case, and in the mid to late 1980s the UHE gamma-ray output showed a steady decline apart from transient UHE emission following giant radio flares. With the exception of possible detections above 10 n eV by the Fly's Eye and Akeno Array, I am unaware of any statistically compelling claimed detections of this source reported over the past 4 years. The new arrays-C ASA-MI A and SPASE-have not detected any of the claimed sources, and it seems likely that at least some of these early claims may have been premature. However, although none of the observations taken alone was of extremely high statistical significance, the observations of Cygnus X-3 by different groups showed a consistency which I feel cannot be ascribed to chance alone. The observations of Cygnus X-3 and the Crab Nebula/Pulsar are reviewed with particular reference to the results published during the last 5 years.

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Section: Status Of Ultra-high-energy 7-ray Observations 885 23 Obsementioning

confidence: 83%

Section: Status Of Ultra-high-energy 7-ray Observations 885 23 Obsementioning

confidence: 99%

The Status of Ultra-High-Energy Gamma-Ray Observations

Protheroe

1994

International Astronomical Union Colloquium

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“…Using parts of the eventual CASA-MIA detector, some of us reported limits for data taken in 1988-1989 [45] and in 1989 [46]. The general trend of a "quiet" Cygnus X-3 continued into the early 1990's, although there were several publications claiming gamma-ray emission based largely on data that had been taken in the previous decade [47,48,49].…”

Section: Discussion Of the Sources And Earlier Resultsmentioning

confidence: 99%

High statistics search for ultrahigh energy γ-ray emission from Cygnus X-3 and Hercules X-1

et al. 1997

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We have carried out a high statistics (2ϫ10 9 events͒ search for ultrahigh energy ␥-ray emission from the x-ray binary sources Cygnus X-3 and Hercules X-1. Using data taken with the CASA-MIA detector over a five year period ͑1990-1995͒, we find no evidence for steady emission from either source. The derived 90 % C.L. upper limit to the steady integral flux of ␥ rays from Cygnus X-3 is ⌽(EϾ115 TeV͒Ͻ6.3ϫ10 Ϫ15 photons cm Ϫ2 sec Ϫ1 , and from Hercules X-1 it is ⌽(EϾ115 TeV)Ͻ8.5ϫ10 Ϫ15 photons cm Ϫ2 sec Ϫ1 . These limits are more than two orders of magnitude lower than earlier claimed detections and are better than recent experiments operating in the same energy range. We have also searched for transient emission on time periods of one day and 0.5 h and find no evidence for such emission from either source. The typical daily limit on the integral ␥-ray flux from Cygnus X-3 or Hercules X-1 is ⌽ daily (EϾ115 TeV)Ͻ2.0ϫ10 Ϫ13 photons cm Ϫ2 sec Ϫ1 . For Cygnus X-3, we see no evidence for emission correlated with the 4.8 h x-ray periodicity or with the occurrence of large radio flares. Unless one postulates that these sources were very active earlier and are now dormant, the limits presented here put into question the earlier results, and highlight the difficulties that possible future experiments will have in detecting ␥-ray signals at ultrahigh energies. ͓S0556-2821͑97͒07004-5͔ PACS number͑s͒: 98.70. Rz, 95.85.Pw, 96.40.Pq, 98.70.Sa

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Section: Burst Activity and Emission Associated With Radio Flaringmentioning

confidence: 91%

The status of ultra-high-energy gamma-ray observations

Protheroe¹

1994

ApJS

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In 1983 Samorski and Stamm found evidence of ultra-high-energy (UHE) gamma-ray eniission from Cygnus X-3 in archival data from the Kiel air shower array. The emission appeared to be emitted only at one phase in the binary orbit. The Kiel array was sensitive to air showers generated by particles with energies above 3 X 10 15 eV. Their discovery led to searches in archival data from other arrays for evidence of UHE emission from Cygnus X-3 and other potential sources in the Galaxy, and to the construction of new air shower arrays dedicated to UHE astronomy.In the mid 1980s many groups around the world claimed detections of Cygnus X-3, Hercules X-l, Vela X-l, and other objects. Cygnus X-3 is strongly variable at all wavelengths, and so it would be surprising if this variability did not extend to UHE gamma-rays also. This indeed appeared to be the case, and in the mid to late 1980s the UHE gamma-ray output showed a steady decline apart from transient UHE emission following giant radio flares. With the exception of possible detections above 10 17 eV by the Fly's Eye and Akeno Array, I am unaware of any statistically compefling claimed detections of this source reported over the past 4 years. The new arrays-CASA-MIA and SPASE-have not detected any of the claimed sources, and it seems likely that at least some of these early claims may have been premature. However, although none of the observations taken alone was of extremely high statistical significance, the observations of Cygnus X-3 by different groups showed a consistency which I feel cannot be ascribed to chance alone. The observations of Cygnus X-3 and the Crab Nebula/Pulsar are reviewed with particular reference to the results published during the last 5 years. Subject headings: gamma rays: observations -pulsars: individual (Crab Nebula)stars: individual (Cygnus X-3)

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

Cited by 7 publications

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The Status of Ultra-High-Energy Gamma-Ray Observations

The Status of Ultra-High-Energy Gamma-Ray Observations

High statistics search for ultrahigh energy γ-ray emission from Cygnus X-3 and Hercules X-1

The status of ultra-high-energy gamma-ray observations

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