First Stars, Very Massive Black Holes, and Metals

By R. Schneider, A. Ferrara, P. Natarajan, K. Omukai. 2001

358 citations recorded by the source corpus.

Recent studies suggest that the initial mass function (IMF) of the first stars (Population III) is likely to have been extremely top-heavy, unlike what is observed at present. We propose a scenario to generate fragmentation to lower masses once the first massive stars have formed and derive constraints on the primordial IMF. We estimate the mass fraction of pair-unstable supernovae (SNγγ), shown to be the dominant sources of the first heavy elements. These metals enrich the surrounding gas up to ≈10-4 Z☉, when a transition to efficient cooling-driven fragmentation producing ≲1 M☉ clumps occurs. We argue that the remaining fraction of the first stars ends up in ≈100 M☉ VMBHs (very massive black holes). If we further assume that all these VMBHs are likely to end up in the centers of galactic nuclei constituting the observed supermassive black holes (SMBHs), then ≈6% of the first stars contributed to the initial metal enrichment and the IMF remained top-heavy down to a redshift z ≈ 18.5%. Interestingly, this is the epoch at which the cool metals detected in the Lyα forest at z ≈ 3 must have been ejected from galaxies. At the other extreme, if none of these VMBHs has as yet ended up in SMBHs, we expect them to be either (1) en route toward galactic nuclei, thereby accounting for the X-ray-bright off-center sources detected locally by ROSAT, or (2) the dark matter candidate composing the entire baryonic halos of galaxies. For case 1 we expect all but a negligible fraction of the primordial stars to produce metals, causing the transition at the maximum possible redshift of ≳22.1, and for case 2, ~3 × 105, a very negligible fraction of the initial stars produce the metals and the transition redshift occurs at zf ≳ 5.4. In this paper, we present a framework (albeit one that is not stringently constrained at present) that relates the first episode of star formation to the fate of their remnants at late times. Clearly, further progress in understanding the formation and fragmentation of Population III stars within the cosmological context will provide tighter constraints in the future. We conclude with a discussion of several hitherto unexplored implications of a high-mass-dominated star formation mode in the early universe.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/09c84343d090f0af93af9a1d89be8113f81ba304

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Citations in the corpus

X-ray pre-ionization powered by accretion on the first black holes – I. A model for the WMAP polarization measurement (2003, background): “An interesting consequence of this scenario is a copious production of BHs from the first stars (Schneider et al. 2002).”
A case study of hurdle and generalized additive models in astronomy: the escape of ionizing radiation (2018, background): “The early generations of stars (Schneider et al. 2002; Maio et al. 2010; De Souza et al. 2013; Schauer et al. 2015) are likely among the major players of this transformation, which thus strongly depends on the (poorly known) high-z stellar properties.”
Self-regulated growth of supermassive black holes by a dual jet-heating active galactic nucleus feedback mechanism: methods, tests and implications for cosmological simulations (2011, background): “These can produce BH remnants as massive as 102–103 M (Madau & Rees 2001; Heger & Woosley 2002; Schneider et al. 2002) that will eventually rapidly merge in their primordial halo to reach even larger masses.”
Chemical Evolution in Hierarchical Models of Cosmic Structure. I. Constraints on the Early Stellar Initial Mass Function (2005, background): “Recent theoretical work has focused on a priori estimates of the “critical metallicity”, Zcr ∼ 10−5− 10−3Z⊙ (Schneider et al. 2002; Bromm & Loeb 2003; Santoro & Shull 2005), above which gas can cool and fragment to ∼ 1 M⊙.”
The first galaxies : assembly, cooling and the onset of turbulence (2008, background): “…2006; Spaans & Silk 2006; Wise et al. 2007), or via merging and accretion of gas on to the compact remnants of Pop III stars (Madau & Rees 2001; Schneider et al. 2002; Islam et al. 2003; Volonteri et al. 2003; Volonteri & Rees 2005; Johnson & Bromm 2007; Pelupessy et al. 2007; Wise et al.…”
Star Formation at Very Low Metallicity. I. Chemistry and Cooling at Low Densities (2007, background): “…above a certain level, the so-called critical metallicity, leads to a significant change in the stellar initial mass function (IMF), from an IMF dominated by massive stars to one that looks far more like the familiar Salpeter IMF of local star formation (Bromm et al. 2001; Schneider et al. 2002).”
Population III stars: hidden or disappeared? (2007, result): “This idea has been later on expanded and substantiated by a number of detailed studies (Omukai 2000; Bromm et al. 2001; Schneider et al. 2002, 2003).”
How Massive Single Stars End Their Life (2002, background): “If the IMF becomes more top-heavy at low metallicity (d10 4 Z ; Bromm et al. 2001; Schneider et al. 2002), the number of core-collapse supernovae (mostly Type IIp) and GRBs (if occurring in single stars) should significantly increase at high redshift.”
The first stars: formation of binaries and small multiple systems (2009, background): “The resulting metallicity was likely crucial in governing the transition from early highmass star formation to the normal-mass star formation seen today (e.g. Omukai 2000; Bromm et al. 2001; Schneider et al. 2002; Bromm & Loeb 2003; Frebel et al. 2007, 2009; Smith & Sigurdsson 2007).”
The First Stellar Cluster (2007, background): “Another possibility, and the one that we explore with this paper, is that low mass star formation is a result of dust-induced fragmentation occurring at high densities, and thus at a very late stage in the protostellar collapse (Schneider et al. 2002; Omukai et al. 2005; Schneider et al. 2006).”
Early Reionization by Miniquasars (2003, background): “…Nonrotating very massive stars in the mass window 140 ∼< m∗ ∼< 260 M⊙ will disappear as pair-instability supernovae (Bond, Arnett, & Carr 1984), leaving no compact remnants and polluting the universe with the first heavy elements (e.g. Schneider et al. 2002; Oh et al. 2001; Wasserburg & Qian 2000).”
The First Cosmic Structures and Their Effects (2004, background): “…first supernova explosions pollute with metals the gas out of which subsequent generations of lowmass Pop II/I stars form, driving a transition from a top-heavy IMF to a “Salpeter-like” IMF when locally the metallicity approaches the critical value Zcr = 10 −5±1Z⊙ (Schneider et al. 2002, 2003).”
Blossoms from black hole seeds: properties and early growth regulated by supernova feedback (2016, background): “…star remnants” scenario, BHs are predicted to form in mini-haloes (Mh ≈ 105 M ) with gas below a critical metallicity (Z < 10−3.5 Z , Bromm et al. 2001; Schneider et al. 2002) at redshift z = 30−20 from the remnants of the first generation of stars (PopIII, Madau & Rees 2001; Volonteri, Madau &…”
Cosmological simulations of the growth of supermassive black holes and feedback from active galactic nuclei: method and tests (2009, background): “…mechanisms include the collapse of Population III stars, giving rise to BHs with masses in the range 102 < mBH < 103 M (e.g. Madau & Rees 2001; Schneider et al. 2002; Islam, Tayloe & Silk 2003), and direct collapse of matter in high-redshift, low angular momentum haloes, which may give rise…”
Early reionization by the first galaxies (2003, background): “Stars of this mass may cease to form once the metallicity of the parent gas cloud exceeds Z ≈ 10−5±1 Z (Bromm et al. 2001; Schneider et al. 2002).”
The Detectability of the First Stars and Their Cluster Enrichment Signatures (2003, methodology): “This situation leads to the so-called star formation conundrum pointed out in Schneider et al. (2002a).”
Two populations of metal-free stars in the early Universe (2006, background): “Once the metallicity of the IGM exceeds a critical level, the formation of primordial, metal-free stars is suppressed and star formation switches to a more conventional mode (e.g. Omukai 2000; Bromm et al. 2001a; Schneider et al. 2002).”