Search for pulsed tev gamma‐ray emission from the crab pulsar

Lessard, R. W.
Bond, I. H.
Bradbury, S. M.
Buckley, J. H.
Burdett, A. M.
Carter‐Lewis, D. A.
Catanese, M.
Cawley, M. F.
D’Vali, M.
Fegan, D. J.
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Lessard, R. W. Bond, I. H.; Bradbury, S. M.; Buckley, J. H.; Burdett, A. M.; Carter‐Lewis, D. A.; Catanese, M.; Cawley, M. F.; D’Vali, M.; Fegan, D. J.; Finley, J. P.; Gaidos, J. A.; Gillanders, G. H.; Hall, T.; Hillas, A. M.; Krennrich, F.; Lang, M. J.; Masterson, C.; Moriarty, P.; Quinn, J.; Rose, H. J.; Samuelson, F. W.; Sembroski, G. H.; Srinivasan, R.; Vassiliev, V. V.; Weekes, T. C. (2000). Search for pulsed tev gamma‐ray emission from the crab pulsar. The Astrophysical Journal 531 (2), 942-948
We present the results of a search for pulsed TeV emission from the Crab pulsar using the Whipple Observatory's 10-m gamma-ray telescope. The direction of the Crab pulsar was observed for a total of 73.4 hr between 1994 November and 1997 March. During this period the Whipple 10 m telescope was operated at its lowest energy threshold to date. Spectral analysis techniques were applied to search for the presence of a gamma-ray signal from the Crab pulsar over the energy band 250 GeV to 4 TeV. We do not see any evidence of the 33 ms pulsations present in other energy bands from the Crab pulsar. The 99.9% confidence level upper limit for pulsed emission above 250 GeV is derived to be 4.8 x 10(-12) cm(-2) s(-1) or less than 3% of the steady flux from the Crab Nebula. These results imply a sharp cutoff of the power-law spectrum seen by the EGRET instrument on the Compton Gamma-Ray Observatory. If the cutoff is exponential, it must begin at 60 GeV or lower to accommodate these upper limits.
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