2013ApJ...763L..28C

Super-luminous supernovae have a tendency to occur in faint host galaxies which are likely to have low mass and low metallicity. While these extremely luminous explosions have been observed from z = 0.1 to 1.55, the closest explosions allow more detailed investigations of their host galaxies. We present a detailed analysis of the host galaxy of SN 2010gx (z = 0.23), one of the best studied super-luminous type Ic supernovae. The host is a dwarf galaxy (M_g= -17.42±0.17) with a high specific star formation rate. It has a remarkably low metallicity of 12 + log (O/H) = 7.5±0.1 dex as determined from the detection of the [O III] λ4363 line. This is the first reliable metallicity determination of a super-luminous stripped-envelope supernova host. We collected deep multi-epoch imaging with Gemini + GMOS between 240 and 560 days after explosion to search for any sign of radioactive ⁵⁶Ni, which might provide further insights on the explosion mechanism and the progenitor's nature. We reach griz magnitudes of m_AB∼ 26, but do not detect SN 2010gx at these epochs. The limit implies that any ⁵⁶Ni production was similar to or below that of SN 1998bw (a luminous type Ic SN that produced around 0.4 M_☉ of ⁵⁶Ni). The low volumetric rates of these supernovae (∼10^–4 of the core-collapse population) could be qualitatively matched if the explosion mechanism requires a combination of low-metallicity (below 0.2 Z_☉), high progenitor mass (>60 M_☉) and high rotation rate (fastest 10% of rotators).