galaxies are dominated by strong emission lines produced by nebulae associated with high mass stars ($>$15[M$_\odot$]{}) and therefore provide a direct tracer of the high mass end of the IMF [@Bastian2010]. Due to the recent development of sensitive near infra-red (NIR) imagers and multiplexed spectrographs that take advantage of the Y, J, H, and K atmospheric windows, the $z\sim2$ universe is ideal to study rest frame optical features of galaxies.

Investigating the IMF with [H$\alpha$]{} Emission {#sec:method}
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The total flux of a galaxy at [H$\alpha$]{} emission wavelength is the sum of the [H$\alpha$]{} emission flux, the continuum level at the same wavelength minus the [H$\alpha$]{} absorption. [H$\alpha$]{} absorption for galaxies at $z\sim2$ is $\leq$ 3% of its flux level [@Reddy2015] and therefore can be ignored. In case B recombination [@Brocklehurst1971], following the Zanstra principle [@Zanstra1927] the [H$\alpha$]{} flux of a galaxy is directly related to the number of Lyman continuum photons emitted by massive young O and B stars with masses $>$10[M$_\odot$]{}. The continuum flux at the same wavelength is dominated by red giant stars with masses between $0.7-3.0$ [M$_\odot$]{}. Therefore, [H$\alpha$]{} EW, that is the ratio of the strength of the emission line to the continuum level can 