The properties of the host galaxy and the immediate environment of GRB 980425/SN 1998bw from the multiwavelength spectral energy distribution

We present an analysis of the spectral energy distribution (SED) of the galaxy ESO 184-G82, the host of the closest known long gamma-ray burst (GRB) 980425 and its associated supernova (SN) 1998bw. We use our observations obtained at the Australia Telescope Compact Array (the third >3σ radio detection of a GRB host) as well as archival infrared and ultraviolet (UV) observations to estimate its star formation state. We find that ESO 184-G82 has a UV star formation rate (SFR) and stellar mass consistent with the population of cosmological GRB hosts and of local dwarf galaxies. However, it has a higher specific SFR (per unit stellar mass) than luminous spiral galaxies. The mass of ESO 184 G82 is dominated by an older stellar population in contrast to the majority of GRB hosts. The Wolf–Rayet region ∼ 800 pc from the SN site experienced a starburst episode during which the majority of its stellar population was built up. Unlike that of the entire galaxy, its SED is similar to those of cosmological submillimeter/radio-bright GRB hosts with hot dust content. These findings add to the picture that in general, the environments ofGRBs on 1–3 kpc scales are associated with high specific SFR and hot dust