uncertainties, which may arise due to K corrections if we are to redshift the galaxy spectra to $z=0.1$ from $z=0$.

Galaxy Spectral Models {#sec:PEGASE_models}
======================

In this section, we describe the theoretical galaxy stellar spectral models employed to investigate the effect of IMF, SFHs, and other fundamental galaxy properties in [H$\alpha$]{} EW vs optical colour parameter space. We use PEGASE.2 detailed in @Fioc1997 as our primary spectral synthesis code to perform our analysis and further employ Starburst99 [@Leitherer1999] and BPASSv2 [@Eldridge2016] models to investigate the effects of other exotic stellar features.

PEGASE is a publicly available spectral synthesis code developed by the Institut d’Astrophysique de Paris. Once the input parameters are provided, PEGASE produces galaxy spectra for varying time steps, which can be used to evaluate the evolution of fundamental galaxy properties over cosmic time.

Model Parameters
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In this paper, we primarily focus on the effect of varying the IMF, SFH, and metallicity on [H$\alpha$]{} EW and optical colour of galaxies. A thorough description of the behaviour of PEGASE models in this parameter space can be found in [@Hoversten2008]. The parameters we vary are as follows.

-   [**The IMF :**]{} we follow HG08 and use an IMF with a 