Detecting Population III Stars through Tidal Disruption Events in the Era of JWST and Roman

Abstract

The first generation metal-free stars, referred to as population III (Pop III) stars, are believed to be the first objects to form out of the pristine gas in the very early Universe. Pop III stars have different structures from current generation of stars and are important for generating heavy elements and shaping subsequent star formation. However, it is very challenging to directly detect Pop III stars given their high redshifts and short life-times. In this paper, we propose a novel method for detecting Pop III stars through their tidal disruption events (TDEs) by massive black holes. We model the emission properties and calculate the expected rates for these unique TDEs in the early Universe at z ~ 10. We find that Pop III star TDEs have much higher mass fallback rates and longer evolution timescales compared to solar-type star TDEs in the local universe, which enhances the feasibility of their detection, although a good survey strategy will be needed for categorizing these sources as transients. We further demonstrate that a large fraction of the flare emissions are redshifted to infrared wavelengths, which can be detected by the James Webb Space Telescope and the Nancy Grace Roman Space Telescope. Last but not least, we find a promising Pop III star TDE detection rate of up to a few tens per year using the Nancy Grace Roman Space Telescope, based on our current understanding of the black hole mass function in the early Universe.