Modelling the Reionization Era Galaxies’ Analog

Even in the first year of operation, James Webb Space Telescope (JWST) has revolutionized the study of reionization-era galaxies, by providing deep ultra-violet (UV) and optical spectra of these galaxies. These spectra contain several information about the ionized gas and stellar population of these systems. We present a python package which aims to enable users to do detailed modelling of spectral features including the continuum, absorption and emission lines within the UV and optical spectra of galaxies. The code incorporates the flexibility to use two major population synthesis model libraries, STARBURST (Leitherer+1999) and BPASS (Stanway+2018), thus investigating the role of both single star and binary star populations. We will present the major features of this code via modelling the high quality spectra of a nearby dwarf galaxy, Pox 186 (Kumari+2023). These spectra are taken with the Cosmic Origin Spectrograph on the Hubble Space Telescope (HST) and show several UV and optical spectral features indicating that this galaxy is potentially the best local analog of reionization era galaxies. Pox 186 is, therefore, the best example case for developing a software applicable to both local as well as reionization era galaxies. The availability of such a software to the community will allow a uniform analysis of the ionized gas and stellar properties of galaxies, which is essential for consistent interpretations of the wealth of data available with the simultaneous operation of HST and JWST, thus shedding light on the questions related to the galaxy formation and evolution.