FeII] as a tracer of supernova rate in nearby starburst galaxies

Abstract

Supernovae play an integral role in the feedback of processed material into the ISM of galaxies and are responsible for much of the chemical enrichment of the universe. The rate of supernovae can also reveal the star formation histories. Supernova rates are usually measured through the non-thermal radio continuum luminosity; however, a correlation between near-infrared [FeII] emission and supernova remnants has also been noted. We aim to find a quantitative relationship between the [FeII] at 1.26 um ([FeII]$_{1.26}$) luminosity and supernova rate in a sample of 11 near-by starburst galaxy centers. We perform a pixel-pixel analysis of this correlation on SINFONI data cubes. Using Br$\gamma$ equivalent width and luminosity as the only observational inputs into the Starburst 99 model, we derive the supernova rate at each pixel and thus create maps of supernova rates. We then compare these morphologically and quantitatively to the [FeII]$_{1.26}$ luminosity. We have found that a strong linear and morphological correlation exists between supernova rate and [FeII]$_{1.26}$ on a pixel-pixel basis: \[ log\frac{\nu_{SNrate}}{yr^{-1}pc^{-2}} = 1.01 \pm 0.2\ast log\frac{[FeII]_{1.26}}{erg s^{-1}pc^{-2}} - 41.17 \pm 0.9\] This relation is valid for normal star forming galaxies but breaks down for extreme ultra luminous galaxies. The supernova rates derived from the Starburst 99 model are in good agreement with the radio-derived supernova rates, which underlines the strength of using [FeII] emission as a tracer of supernova rate. With the strong correlation found in this sample of galaxies, we conclude that [FeII]$_{1.26}$ emission can be generally used to derive accurate supernova rates on either a pixel-pixel or integrated galactic basis.