Modelling of SN2013dx associated with the low-redshift GRB130702A points to diversity in GRB/SN properties

The properties of the broad-lined Type Ic supernova (SN) 2013dx, associated with the long gamma-ray burst GRB130702A at a redshift z = 0.145, are derived via spectral modelling. SN2013dx was similar in luminosity to other GRB/SNe, with a derived value of the mass of Ni-56 ejected in the explosion of approximate to 0.4M(circle dot). However, its spectral properties suggest a smaller explosion kinetic energy. Radiation transport models were used to derive a plausible mass and density distribution of the SN ejecta in a one-dimensional approximation. While the mass ejected in the explosion that is obtained from the modelling (M-ej approximate to 9M(circle dot)) is similar to that of all other well-studied GRB/SNe, the kinetic energy is significantly smaller (E-K similar to 10(52)erg). This leads to a smaller E-K/M-ej ratio, approximate to 10(51)erg/M-circle dot, which is reflected in the narrower appearance of the spectral lines. While the low E-K does not represent a problem for the scenario in which magnetar energy aids powering the explosion and the nucleosynthesis, it is nevertheless highly unusual. SNeIc with similar E-K have never been seen in coincidence with a GRB, and no well-observed GRB/SN has shown similarly low E-K and E-K/M-ej.

Automated summary

The broad-lined Type Ic supernova SN2013dx, associated with the long gamma-ray burst GRB130702A, has properties similar to other GRB/SNe in terms of mass of Ni-56 ejected, but has a significantly smaller explosion kinetic energy. This leads to narrower spectral lines and is highly unusual for supernovae associated with gamma-ray bursts.