Limits on the Cosmological Abundance of Supermassive Compact Objects from a Millilensing Search in Gamma-Ray Burst Data

A new search for the gravitational lens effects of a significant cosmological density of supermassive compact objects (SCOs) on gamma-ray bursts (GRBs) has yielded a null result. We inspected the timing data of 774 BATSE-triggered GRBs for evidence of millilensing: repeated peaks similar in light-curve shape and spectra. Our null detection leads us to conclude that, in all candidate universes simulated, Omega(SCO)<0.1 is favored for SCO masses in the range 10(5)<M(SCO)/M( middle dot in circle)<10(9), while in some universes and mass ranges the density limits are as much as 10 times lower. Therefore, a cosmologically significant population of SCOs near globular cluster mass did not come out of the primordial universe or condense at recombination.