An IMF Study of the Dwarf Starburst Galaxy NGC 4214

TL;DR

This study investigates the upper end of the stellar initial mass function in NGC 4214 using Hubble data, finding it to be largely universal and highlighting the effects of stochastic sampling and feedback on observed properties.

Contribution

It provides evidence that the upper IMF is universal in NGC 4214 and discusses the impact of stochastic sampling and feedback on stellar and nebular observations.

Findings

Upper IMF appears universal in NGC 4214.

Stochastic sampling affects low-mass clusters.

Feedback influences Hα luminosity in massive clusters.

Abstract

The production rate of ionizing photons in young < 8 Myr, unresolved stellar clusters in the nearby irregular galaxy NGC 4214 is probed using multi-wavelength Hubble Space Telescope WFC3 data. We normalize the ionizing photon rate by the cluster mass to investigate the upper end of the stellar initial mass function (IMF). We have found that within the uncertainties the upper end of the stellar IMF appears to be universal in this galaxy, and that deviations from a universal IMF can be attributed to stochastic sampling of stars in clusters with masses < 10^3 M_sun. Furthermore, we have found that there does not seem to be a dependence of the maximum stellar mass on the cluster mass. We have also found that for massive clusters, feedback may cause an underrepresentation in Ha luminosities, which needs to be taken into account when conducting this type of analysis.