Two populations of metal-free stars in the early Universe

By Thomas Greif, Volker Bromm. 2006

140 citations recorded by the source corpus.

We construct star formation histories at redshifts z? 5 for two physically distinct populations of primordial, metal-free stars, motivated by theoretical and observational arguments that have hinted towards the existence of an intermediate stellar generation between Population III and Population I/II. Taking into account the cosmological parameters as recently revised by the Wilkinson Microwave Anisotropy Probe after three years of operation, we determine self-consistent reionization histories and discuss the resulting chemical enrichment from these early stellar generations. We find that the bulk of ionizing photons and heavy elements produced at high redshifts must have originated in Population II.5 stars, which formed out of primordial gas in haloes with virial temperatures?10 4 K, and had typical masses?10M ⊙ . Classical Population III stars, formed in minihaloes and having masses?100 M ⊙ , on the other hand, had only a minor impact on reionization and early metal enrichment. Specifically, we conclude that only ≃ 10 per cent by mass of metal-free star formation went into Population III.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/012e5e9cc1f9443a345aaf4c517f95ff8bdb81c2

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In Astronomy and Astrophysics

1. P. Hopkins
2. L. Hernquist
3. S. Glover
4. Volker Springel
5. Tom Abel
6. R. Dav'e
7. John H. Wise
8. Volker Bromm

Citations in the corpus

• Production of dust by massive stars at high redshift (2011, background): “The very first stars (Pop III.1) formed in isolation and are expected to have been relativelyrare, only about 10% by mass of all generations of Pop III stars (e.g., Greif and Bromm, 2006; McKee and Tan, 2008).”
• THE SPECTRAL EVOLUTION OF THE FIRST GALAXIES. I. JAMES WEBB SPACE TELESCOPE DETECTION LIMITS AND COLOR CRITERIA FOR POPULATION III GALAXIES (2011, methodology): “Due to the lack of efficient coolants in metalfree, primordial gas, the first stars to form in our Universe were likely very massive (& 10 M⊙ and possibly even up to 1000 M⊙; e.g. Bromm et al. 1999; Nakamura & Umemura 2002; Tan & McKee 2004; Greif & Bromm 2006; Ohkubo et al. 2009).”
• Conditions for Reionizing the Universe with a Low Galaxy Ionizing Photon Escape Fraction (2019, methodology): “…of this method, Population III stars are not predicted to contribute significantly to the reionizing budget (e.g., Ricotti & Ostriker 2004; Greif & Bromm 2006; Ahn et al. 2012; Paardekooper et al. 2013); thus, we do not consider star formation in molecular-cooling halos in this work…”
• Early Cosmological H II/He III Regions and Their Impact on Second-Generation Star Formation (2006, background): “Stars formed in such gas clouds likely have a smaller mass (<40 M ) than the first generation of stars and hence may be progenitors of supernovae that enriched the gas from which recently discovered hyperYmetal-poor stars were born (Iwamoto et al. 2005; Greif & Bromm 2006).”
• Population III stars: hidden or disappeared? (2007, background): “…& Shull 2002; Machacek, Bryan, Abel 2003; Omukai & Yoshii 2003; Yoshida et al. 2003; Susa & Umemura 2006), HD chemistry (Nagakura & Omukai 2005; Greif & Bromm 2006; Johnson & Bromm 2006; Yoshida et al. 2007) and radiative transfer (Ciardi, Ferrara & Abel 2000; Ricotti, Gnedin & Shull 2001;…”
• The Formation of the First Stars. II. Radiative Feedback Processes and Implications for the Initial Mass Function (2007, background): “Those Population III.2 stars that form out of gas that is enriched in HD will typically be less massive than Population III.1 stars, by about a factor of 10 according to Greif & Bromm (2006).”
• The aftermath of the first stars: massive black holes (2006, background): “This is comparable to the background LW flux that is expected to have been established by the first generations of stars at redshifts z >∼ 15 (e.g. Greif & Bromm 2006).”
• The First Billion Years project: the impact of stellar radiation on the co-evolution of Populations II and III (2012, methodology): “…2001; Schaerer 2002), but also lead to only a modest decrease in the efficiency of molecule-dissociating, Lyman-Werner (LW) photon production (e.g. Greif & Bromm 2006), as well as to an increased efficiency in the production of H−-ionizing photons (e.g. Shang et al. 2010).1 Thus, the high energy…”
• The birth of a galaxy – III. Propelling reionization with the faintest galaxies (2014, background): “…massive, metal-free (Population III; Pop III) stars can contribute of the order of 10 per cent of the budget (Ricotti & Ostriker 2004a; Greif & Bromm 2006; Trac & Cen 2007; Wise & Abel 2008a; Ahn et al. 2012; Wise et al. 2012b; Johnson, Dalla & Khochfar 2013; Paardekooper, Khochfar &…”
• Probing the formation of the first low‐mass stars with stellar archaeology (2007, background): “…has shown that the fraction of metal-poor stars in the halo may not differ greatly from that in the bulge (see also Brook et al. 2006), suggesting that the halo abundances shown in Figure 1 may indeed be representative of the most metal-poor stars in the Milky Way (but see Greif & Bromm 2006).”
• Effects of rotation on the evolution of primordial stars (2008, background): “Since this first suggestion that PopIII may not all be very massive objects, several studies have shown that the radiation field of a pre-existing star has a strong impact on subsequent star formation (Omukai & Yoshii 2003; O’Shea et al. 2005; Greif & Bromm 2006).”
• Ubiquitous seeding of supermassive black holes by direct collapse (2012, background): “It can be computed following the formulae in Greif & Bromm (2006): J IIIbg ≃ fesc hc 4πmH ηIIILWρ III ∗ (1 + z) 3 , (12) J IIbg ≃ fesc hc 4πmH ηIILWρ II ∗ (1 + z) 3 , (13) wherefesc is the escape fraction of LW photons from the halo, ρIII∗ , ρ II ∗ denote the comoving density of Pop III and Pop II…”
• Near-Field Cosmology with Extremely Metal-Poor Stars (2015, background): “In particular, whereas cooling in the first phase of star formation was provided by H2, in this second phase cooling would be driven by HD leading to lower gas temperatures and smaller stellar masses (e.g., Johnson & Bromm 2006 and Greif & Bromm 2006).”
• The first galaxies : assembly, cooling and the onset of turbulence (2008, methodology): “This latter mode had previously been termed Pop II.5 (Mackey et al. 2003; Greif & Bromm 2006; Johnson & Bromm 2006).”
• Formation and evolution of primordial protostellar systems (2012, background): “A second, less important coolant is hydrogen deuteride (HD), which may become relevant at low temperatures due to its permanent dipole moment (Flower et al. 2000; Nakamura & Umemura 2002; Greif & Bromm 2006; Johnson & Bromm 2006; Ripamonti 2007; McGreer & Bryan 2008).”
• CANDELS: THE CONTRIBUTION OF THE OBSERVED GALAXY POPULATION TO COSMIC REIONIZATION (2012, background): “Their overall contribution to reionization may, however, have been limited (e.g., Greif & Bromm 2006).”
• Resolving the Formation of Protogalaxies. II. Central Gravitational Collapse (2007, methodology): “From prior studies (e.g., Abel et al. 2002; Bromm & Loeb 2003; O’Shea et al. 2005; Greif & Bromm 2006), we expect these stars to form to in halos that can support H2 cooling and ones embedded in relic H ii regions.”