An analysis of the 11 HETE-2 GRBs with known redshifts appears to confirm the evidence for a correlation between GRB isotropic-equivalent luminosity/energy and redshift --- higher redshift GRBs appear to be brighter and more energetic. I will present the results of the analysis, in which we combine the HETE-2 sample with 10 BeppoSAX GRBs and correct for threshold effects. These results strengthen the previous evidence from analyses of the BATSE catalog, and of the BeppoSAX GRBs alone. If the isotropic-equivalent energies and luminosities of GRBs really do increase with redshift, it suggests that GRB jets at high redshifts may be narrower and thus the cores of GRB progenitor stars at high redshifts may be rotating more rapidly. It also suggests that GRBs at very high redshifts may be more luminous -- and therefore easier to detect – than has been thought, which would make GRBs a more powerful probe of cosmology and the early universe than has been thought.
Tuesday, February 24th
Seminar is to be held at 4:00 PM in the conference room
on the second floor of Dearborn Observatory
Refreshments will be served at 3:30
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