Vol. 581
In section 4. Extragalactic astronomy

Are long gamma-ray bursts biased tracers of star formation? Clues from the host galaxies of the Swift/BAT6 complete sample of LGRBs. I. Stellar mass at z < 1⋆

by S.D. Vergani, R. Salvaterra, J. Japelj, et al. A&A 581, A102

Reconstructing the star formation history of the Universe ever since its onset, a few hundred million years after the Big Bang, up to the present epoch has been one of the major challenges in observational cosmology. However, this attempt must deal with several hurdles. Star formation activity can take place in environments where light is highly obscured by dust or in galaxies that are too faint to be firmly detected. As the most energetic explosions known so far, gamma-ray bursts (GRBs) offer an alternative method of inferring cosmic star formation. A class of relatively long-lasting GRBs is now thought to be connected with the final stages of the evolution of massive stars. Therefore, if a reliable calibration between massive star production and the GRB rate can be established, this would make it possible to use this alternative star formation tracer. In this paper, the authors take an important step in that direction by using a complete sample of low-redshift GRBs observed with Swift/BAT6.