Redshift Horizon for the Origins Space Telescope from Primordial Dust Emission

We explore the possibility of detecting the first galaxies with the next generation Origins Space Telescope (OST) by applying an analytical model of primordial dust emission. By analysing source densities as a function of redshift (z), and considering deep-field exposures with the Origins Survey Spectrometer, we estimate that the redshift horizon for detecting one individual source would be above z~7 for systems with dust-to-metal ratios higher than those expected for typical primeval galaxies. On the other hand, if confusion limits could be overcome, the Far-infrared Imager and Polarimeter would enable the detection of more typical fainter systems at z>7. Given the dependence of the obtained results with the properties of primeval dust, we conclude that the OST could provide important clues to the nature of the interestellar medium in the early Universe.