A complete sample of bright Swift long gamma-ray bursts: Testing the spectral-energy correlations

We use a nearly complete sample of gamma-ray bursts (GRBs) detected by the Swift satellite to study the correlations between the spectral peak energy E _peak of the prompt emission, the isotropic energetics E _iso and the isotropic luminosity L _iso. This GRB sample is characterized by a high level of completeness in redshift (90 per cent). This allows us to probe in an unbiased way the issue related to the physical origin of these correlations against selection effects. We find that one burst, GRB061021, is an outlier to the E _peak-E _iso correlation. Despite this case, we find strong E _peak-E _iso and E _peak-L _iso correlations for the bursts of the complete sample. Their slopes, normalizations and dispersions are consistent with those found with the whole sample of bursts with measured redshift and E _peak. This means that the biases present in the total sample commonly used to study these correlations do not affect their properties. Finally, we also find no evolution with redshift of the E _peak-E _iso and E _peak-L _iso correlations.