Spatially resolved MaNGA observations of the host galaxy of superluminous supernova 2017egm

TL;DR

This study uses spatially resolved MaNGA IFU data to analyze the environment of the nearby superluminous supernova 2017egm in a high-metallicity galaxy, challenging existing theories about SLSN progenitors.

Contribution

First detailed spatial analysis of a high-metallicity SLSN host galaxy, providing new insights into progenitor environments contrary to typical low-metallicity assumptions.

Findings

SN 2017egm occurred in a solar-metallicity environment.

The progenitor star appears to be relatively old based on H-alpha EW.

The host galaxy's properties differ from typical SLSN hosts.

Abstract

Superluminous supernovae (SLSNe) are found predominantly in dwarf galaxies, indicating that their progenitors have a low metallicity. However, the most nearby SLSN to date, SN 2017egm, occurred in the spiral galaxy NGC 3191, which has a relatively high stellar mass and correspondingly high metallicity. In this paper, we present detailed analysis of the nearby environment of SN 2017egm using MaNGA IFU data, which provides spectral data on kiloparsec scales. From the velocity map we find no evidence that SN 2017egm occurred within some intervening satellite galaxy, and at the SN position most metallicity diagnostics yield a solar and above solar metallicity (12 + log (O/H) = 8.8-9.1). Additionally we measure a small H-alpha equivalent width (EW) at the SN position of just 34 Angs, which is one of the lowest EWs measured at any SLSN or Gamma-Ray Burst position, and indicative of the progenitor star being comparatively old. 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 constraints on the progenitors of SLSNe.