{"ID":2918938,"CreatedAt":"2026-06-01T22:54:39.856185535Z","UpdatedAt":"2026-06-01T22:54:39.856185535Z","DeletedAt":null,"paper_url":"https://arxiv.org/abs/1610.05777","arxiv_id":"1610.05777","title":"Limits on Pop III star formation with the most iron-poor stars","abstract":"We study the impact of star-forming mini-haloes, and the Initial Mass Function (IMF) of Population III (Pop III) stars, on the Galactic halo Metallicity Distribution Function (MDF) and on the properties of C-enhanced and C-normal stars at [Fe/H]\u003c-3. For our investigation we use a data-constrained merger tree model for the Milky Way formation, which has been improved to self-consistently describe the physical processes regulating star-formation in mini-haloes, including the poor sampling of the Pop III IMF. We find that only when star-forming mini-haloes are included the low-Fe tail of the MDF is correctly reproduced, showing a plateau that is built up by C-enhanced metal-poor (CEMP) stars imprinted by primordial faint supernovae. The incomplete sampling of the Pop III IMF in inefficiently star-forming mini-haloes (\u003c $10^{-3}$ $M_\\odot$/yr) strongly limits the formation of Pair Instability Supernovae (PISNe), with progenitor masses $m_{\\rm popIII}$=[140-260] $M_\\odot$, even when a flat Pop III IMF is assumed. Second-generation stars formed in environments polluted at \u003e50% level by PISNe are thus extremely rare, corresponding to $\\approx$ 0.25% of the total stellar population at [Fe/H]\u003c-2, which is consistent with recent observations. The low-Fe tail of the MDF strongly depends on the Pop III IMF shape and mass range. Given the current statistics, we find that a flat Pop III IMF model with $m_{\\rm popIII}$=[10-300] $M_\\odot$ is disfavoured by observations. We present testable predictions for Pop III stars extending down to lower masses, with $m_{\\rm popIII}$=[0.1-300] $M_\\odot$.","url_abs":"https://arxiv.org/abs/1610.05777v2","url_pdf":"https://arxiv.org/pdf/1610.05777v2","authors":"M. de Bennassuti, S. Salvadori, R. Schneider, R. Valiante, K. Omukai","published":"2016-10-18T20:00:10Z","has_code":false}