Some First Stars Were Red: Detecting Signatures of Massive Population III Formation Through Long-Term Stochastic Color Variations

Abstract

Identifying stars formed in pristine environments (Pop III) within the first billion years is vital to uncovering the earliest growth and chemical evolution of galaxies. Pop III galaxies, however, are typically expected to be too faint and too few in number to be detectable by forthcoming instruments without extremely long integration times and/or extreme lensing. In an environment, however, where star formation is suppressed until a halo crosses the atomic cooling limit (e.g., by a modest Lyman-Werner flux, high baryonic streaming velocities, and/or dynamical heating effects),primordial halos can form substantially more numerous and more massive stars. Some of these stars will in-turn be accreting more rapidly than they can thermally relax at any given time. Using high resolution cosmological zoom-in simulations of massive star formation in high-z halos, we find that such rapidly accreting stars produce prominent spectral features which would be detectable by {\it JWST}. The rapid accretion episodes within the halo lead to stochastic reprocessing of 0--20\% of the total stellar emission into the rest-frame optical over long timescales, a unique signature which may allow deep observations to identify such objects out to $z\sim 10-13$ using mid- and wide-band NIRCam colors alone.

8 pages, 4 figures, Astrophysical Journal Letters accepted

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Cited by in corpus (4)

• Modelling the cosmological Lyman-Werner background radiation field in the Early Universe
• Conditions for direct black hole seed collapse near a radio-loud quasar 1 Gyr after the Big Bang
• Pulsations of primordial supermassive stars induced by a general relativistic instability; visible to JWST at z$>$12
• 3D hydrodynamics simulations of core convection in supermassive main-sequence stars