Estimation of the Star Formation Rate using Long-Gamma Ray Burst observed by SWIFT

In this work we estimate the star formation rate (SFR) through 333 Long-GRBs detected by Swift. This investigation is based on the empirical model proposed by Yuksel et al. (2008). Basically, the SFR is estimated using long-GRBs considering that they have a stellar origin based on the collapsar model or the collapse of massive stars (hypernovae) M > 20M(circle dot). The analysis starts with the study of epsilon(z) which accounts for the long-GRBs production rate and is parameterized by epsilon(z) = epsilon(0)(1 + z)(delta), where epsilon(0) includes the SFR absolute conversion to GRBs rate in a luminosity range already defined and delta is a dynamical parameter which changes at different regions of redshift; it accounts for the SFR slope which is obtained by an analysis of linear regression over our long-GRBs sample. The results obtained provide evidence that supports our proposal to use Long-GRBs as tracers of SFR.