http://arxiv.org/abs/1708.04618
Superluminous supernovae (SLSNe) have been found predominantly in dwarf galaxies, indicating that their progenitor stars are of low metallicity. However, the most nearby SLSN 2017egm occurred in the spiral galaxy NGC 3191, which has a high stellar mass and correspondingly high metallicity. We present the measurements of the environmental properties at the position of SN 2017egm using MaNGA IFU data, and find that the metallicity at the SN location is 12+log(O/H) = 9.11+/-0.01 in the R23 scale, and 12+log(O/H) = 8.77+/-0.01 in the O3N2 scale. From the velocity map, there is no evidence of a morphological disturbance, or any indication that the SLSN occurred within a satellite galaxy. The equivalent width (EW) of H-alpha at the SN position is 33.7+/-3.3 Angs, and the [O III] nebular line emission is also very low (EW of 2.2+/-0.2 Angs). When using BPASS synthetic population models that include interacting binaries in the populations, the H-alpha EW corresponds to a stellar population with an age of 25-40 Myr and a ZAMS of 8-11 solar mass. This is around two times lower than predications from BPASS models comprising of only single stars. We also compare the observed properties of NGC 3191 with other SLSN host galaxies. The solar-metallicity environment at the position of SN 2017egm presents a challenge to our theoretical understanding, and our spatially resolved spectral analysis provides further constrains on the progenitors of SLSNe.
T. Chen, P. Schady, L. Xiao, et. al.
Thu, 17 Aug 17
13/50
Comments: Submitted to the ApJ Letter, 7 pages, 4 figures and 1 table. Comments are welcome! Good weather for the total solar eclipse!