Testing for a class of ULGRBs using Swift GRBs

Understand

The question of whether ultra-long GRBs form a population different from that of "regular" long GRBs has been much debated recently and during the conference.

• We discuss here the data and the evidence that lead to the conclusion that indeed ultra-long GRBs form a different class of high energy transients.
• The sample of ultra-long GRBs is still poor and the discussion on their origin remain opens, though they might be the signature of PopIII stars.
• We urge that the design of new instrumentation, such as the SVOM satellite, takes into account the need for the detection of distant ultra-long GRBs.