Comparison of the Gamma‐Ray Burst Sensitivity of Different Detectors

Gamma-ray burst detectors are sensitive at different energies, complicatingthe comparison of the burst populations that they detect. The instrument teamsoften report their detector sensitivities in their instruments' energy band. Ipropose that sensitivities be reported as the threshold peak photon flux F_Tover the 1-1000 keV energy band for a specific spectral shape. The primaryspectral parameter is E_p, the energy of the maximum E^2 N_E propto nu f_nu.Thus F_T vs. E_p is a useful description of a detector's sensitivity. I findthat Swift will be marginally more sensitive than BATSE for E_p>100 keV, butsignificantly more sensitive for E_p<100 keV. Because of its low energysensitivity, the FREGATE on HETE-2 is surprisingly sensitive below E_p=100 keV.Both the WFC on BeppoSAX and the WXM on HETE-2 are/were sensitive for low E_p.As expected, the GBM on GLAST will be less sensitive than BATSE, while EXISTwill be significantly more sensitive than Swift. The BeppoSAX GRBM was lesssensitive that the WFC, particularly at low E_p.Comment: 25 pages, 10 figures. To appear in Ap.J, 588 (May 10, '03). Revisions correct FREGATE sensitivity and add a low energy GBM trigger ban