New limit on the size distribution of γ-ray bursts


SINCE the discovery of γ-ray bursts of non-solar origin in 1973 (ref. 1), about 42 events have been confirmed. All have been observed by X-ray and γ-ray detectors on various satellites, though a number of unconfirmed bursts have also been observed by balloon-borne instruments2. The lack of confirmation in the latter cases is not surprising, because of short exposure time and differing sensitivities. The detected flux ranges between about 3 × 10−6 erg cm−2 for the smallest burst to 5 × 10−4 erg cm−2 for the largest observed burst. The integral size distribution of these events above 10−4 erg cm−2 follows an S−1.5 law, suggesting an isotropic distribution of the sources. For events with energy of less than 10−4 erg cm−2, however, the observed distribution seems to flatten out, and the choice of number index (α=0.5,1.0 or 1.5) in this region is not strongly supported by experimental results.

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  1. 1

    Klebesadel, R. W., Strong, I. B., and Olson, R. A., Astrophys. J. Lett., 182, L85 (1973).

  2. 2

    Bewick, A., Coe, M. J., Mills, J. S., and Quenby, J. J., Nature, 258, 686 (1975).

  3. 3

    Strong, I. B., Klebesadel, R. W., and Evans, W. D., Proc. 14th int. Conf. Cosmic Rays, Munchen, 1, 234 (1975).

  4. 4

    Cline, T., and Desai, U. D., Proc. 9th ESLAB Symp., ESRO-SP106, 37 (1974).

  5. 5

    Cowsik, R., Proc. 14th int. Conf. Cosmic Rays, Munchen, 14, 3758 (1975).

  6. 6

    Ramsden, D., and Baker, R., University of Southampton Report.

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CARTER, J., DEAN, A., MANCHADA, R. et al. New limit on the size distribution of γ-ray bursts. Nature 262, 370–371 (1976).

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