REVIEW
The First Stars
Astrophysics · Submitted 3 Nov 2003 · 245 references
Pith's verdict: A solid, careful 2003 synthesis of Population III star formation whose only real soft spot is an abstract that claims more than the body delivers.
T0 · AI review
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Referee report
The paper
The paper claims
The first stars were probably giants, and molecular hydrogen set their mass.
The reading
What carries the argument
The load-bearing mechanism is the $H_2$ cooling curve and the critical density at which it saturates. Below $n_c$ the cooling rate scales as density squared; above it, only linearly, so further compression heats the gas faster than it can radiate and the collapse stalls in a quasi-hydrostatic 'loitering' state. The Jeans mass at that state, $M_J = 700 M_* (T/200 K)^{3/2} (n/10^4 cm^{-3})^{-1/2}$, is the characteristic clump mass and the review's stand-in for the typical stellar mass. The second piece of machinery is the critical metallicity: equating the fine-structure cooling rate of C II or O I to the free-fall compressional heating rate at $T_c$ and $n_c$ gives threshold abundances $[C/H]_{crit} = -3.5$ and $[O/H]_{crit} = -3.05$, the levels above which the gas can keep cooling and fragmenting past the primordial scale.
Extended reading notes
Core claim
The central claim is that Population III star formation is a well-posed and surprisingly robust problem: in cold dark matter cosmologies the first stars form in dark matter minihalos of about $10^6 M_*$ that collapse at redshifts $z$ between 20 and 30, where the virial temperature sits below the $10^4$ K threshold for atomic hydrogen cooling. Cooling therefore falls to molecular hydrogen, and the competition between collisional de-excitation and radiative decay in $H_2$ produces a characteristic state near $T_c = 200$ K and $n_c = 10^4$ cm$^{-3}$ that is largely insensitive to initial conditions. The corresponding Jeans mass of several hundred to a thousand solar masses is the characteristic fragmentation scale, and the review reads the simulation results as evidence that the first stars were predominantly very massive, with typical masses above $100 M_*$. It then identifies the termination of that epoch with chemical feedback: once gas is enriched past a critical carbon or oxygen abundance, fine-structure line cooling lets it fragment to lower masses, converting the primordial mode into the familiar one.
Load-bearing premise
The argument rests on treating the mass of the gravitationally unstable clump, fixed by molecular hydrogen cooling, as a reliable stand-in for the final mass of the star that forms from it, even though the review itself says the final mass is decided by accretion and protostellar feedback that nobody has yet simulated to a conclusion.
Editorial extensions
If this is right
- The first star forming sites are $\sim 10^6 M_*$ minihalos at $z \sim 20-30$, so counting such halos in a cosmological simulation predicts the cosmic history of Population III star formation.
- Because very massive metal-free stars yield far more ionizing photons per stellar baryon than solar-composition stars, an early partial reionization near $z \sim 15$ can account for the large Thomson optical depth, with a second, complete reionization later once Population II stars take over.
- Stars in the 140 to 260 solar mass window end as pair-instability supernovae that leave no remnant and disperse roughly half their mass as metals, with simulations finding about 90 percent of those metals escaping the host minihalo.
- The transition from massive to low-mass star formation should occur once gas reaches $[C/H] \approx -3.5$ or $[O/H] \approx -3.05$, which makes the enrichment history of the intergalactic medium the controller of when that transition happens and how synchronised it is.
- The framework makes the first stars accessible to three kinds of observation: the reionization optical depth, the abundance patterns of the most metal-poor Galactic halo stars, and high-redshift gamma-ray burst afterglows.
Reading between the lines
- The review's own accretion numbers cut against a clean 'all very massive' reading: the simulated accretion rate falls below the critical Eddington-limited value after only a couple of thousand years, at a stellar mass near $25 M_*$, which suggests the primordial mass function may peak at intermediate masses rather than at the top.
- If the first supernovae produce dust efficiently, dust cooling could open a low-mass fragmentation channel at metallicities well below the gas-phase carbon and oxygen thresholds, which would move the Population III to Population II transition to earlier times and lower enrichment levels than the review's numbers imply.
- The double-reionization picture makes a specific prediction for 21 cm cosmology: an early absorption feature from the Population III era, followed by a distinct later one when Population II stars complete reionization, so the two epochs should be separable in the redshifted signal.
- Because minihalo abundance is sensitive to power on small mass scales, a firm upper limit on when the first stars formed would translate into a lower limit on the dark matter particle mass in warm dark matter models.
Original abstract
We review recent theoretical results on the formation of the first stars in the universe, and emphasize related open questions. In particular, we discuss the initial conditions for Population III star formation, as given by variants of the cold dark matter cosmology. Numerical simulations have investigated the collapse and the fragmentation of metal-free gas, showing that the first stars were predominantly very massive. The exact determination of the stellar masses, and the precise form of the primordial initial mass function, is still hampered by our limited understanding of the accretion physics and the protostellar feedback effects. We address the importance of heavy elements in bringing about the transition from an early star formation mode dominated by massive stars, to the familiar mode dominated by low mass stars, at later times. We show how complementary observations, both at high redshifts and in our local cosmic neighborhood, can be utilized to probe the first epoch of star formation.
The compiled record
The paper's own sentences, arranged, kept beside the review and separate from it. Each label is drawn from a closed vocabulary; the number beside it is the probability the classifier gave that label. Numbers in the tables are the authors', checked by code. No sentence in this record was written by a model.
The abstract, sentence by sentence
We review recent theoretical results on the formation of the first stars in the universe, and emphasize related open questions. In particular, we discuss the initial conditions for Population III star formation, as given by variants of the cold dark matter cosmology. Numerical simulations have investigated the collapse and the fragmentation of metal-free gas, showing that the first stars were predominantly very massive. The exact determination of the stellar masses, and the precise form of the primordial initial mass function, is still hampered by our limited understanding of the accretion physics and the protostellar feedback effects. We address the importance of heavy elements in bringing about the transition from an early star formation mode dominated by massive stars, to the familiar mode dominated by low mass stars, at later times. We show how complementary observations, both at high redshifts and in our local cosmic neighborhood, can be utilized to probe the first epoch of star formation.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | We review recent theoretical results on the formation of the first stars in the universe, and emphasize related open questions. | contribution 0.86 | 0.50 | 0.08 | asserted 0.54 |
| s1 | In particular, we discuss the initial conditions for Population III star formation, as given by variants of the cold dark matter cosmology. | contribution 0.57 | 0.17 | 0.04 | asserted 0.82 |
| s2 | Numerical simulations have investigated the collapse and the fragmentation of metal-free gas, showing that the first stars were predominantly very massive. | result 0.50 | 0.07 | 0.24 | asserted 1.00 |
| s3 | The exact determination of the stellar masses, and the precise form of the primordial initial mass function, is still hampered by our limited understanding of the accretion physics and the protostellar feedback effects. | gap 0.64 | 0.08 | 0.09 | asserted 0.98 |
| s4 | We address the importance of heavy elements in bringing about the transition from an early star formation mode dominated by massive stars, to the familiar mode dominated by low mass stars, at later times. | contribution 0.77 | 0.31 | 0.23 | asserted 0.95 |
| s5 | We show how complementary observations, both at high redshifts and in our local cosmic neighborhood, can be utilized to probe the first epoch of star formation. | contribution 0.69 | 0.55 | 0.11 | asserted 0.93 |
What was examined, and what was not
- arXiv listing abstract v1
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- P abstract
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Figures
Figures reproduced from arXiv:astro-ph/0311019 by the authors.
References
How later papers used it
168 later papers cite it
2 later papers by other authors are listed below: 2 used its data or values.
Uses its data or values 2 of 3 papers with this label
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We use LVC data to constrain $f$, assuming the fraction of DBHs in binaries is $f_binary = 0.26$ [ref] .
A gravitational-wave limit on the Chandrasekhar mass of dark matter (2020) · Black Hole Formation from dissipative dark matter · 0.83
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Used this paper's value of N_α=3030 for very massive Population III stars, including higher Lyman series photons, for comparison.
Evolution of the 21 cm signal throughout cosmic history (2008) · 0.80 · paraphrased: the licence does not allow quoting
How the literature uses it
69 arXiv papers cite this in 85 sentences
Papers whose main result relates to this one's
States the same result 1 paper
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I address the importance of heavy elements in bringing about the transition from an early star formation mode dominated by massive stars, to the familiar mode dominated by low mass stars, at later times, and present possible observational probes.
Formation of the First Stars · 0.99
Papers citing it · 52 sentences without a confident label
Uses its method or tool 1 paper
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We forecast HERA's sensitivity to EDE's fractional energy density, $$, by employing a Fisher analysis, following the formalism in Refs. [ref] to construct the Fisher matrix for the 21cm power spectrum, [equation] where $θ_i$ denotes the cosmological and astrophysical parameters we vary in our analysis[We ensure that parameters defined logarithmically are varied linearly.], [equation] Here $L_X^(II/III)$ are the X-ray luminosity of pop-II/III stars (normalized by the SFR in units of $erg s^-1 M_⊙^-1 yr$), $f_*^(II/III)$ are the pop-II/III star formation efficiency, $f_esc^(II/III)$ are the fraction of photons that were produced by pop-II/III stars and managed to escape the host galaxy and ionize the IGM, $α_*^(II/III)$ are the pop-II/III star formation efficiency power law index, whereas $A_LW$ and $A_v_cb$ are the amplitudes of the Lyman-Werner (LW) [ref] and CDM-baryon relative velocity
Early Dark Energy Effects on the 21cm Signal · Fisher analysis · 1.00
Uses its data or values 1 paper
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For comparison, in this notation, the very massive (Population III) stars have [ref] , $N_α=3030$ ($f_α=0.46$), when the contribution from higher Lyman series photons is included.
Evolution of the 21 cm signal throughout cosmic history · Astrophysical modeling · 0.80
Compares with it 2 papers
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For $z ∼7$, when substituting the $M_bound$ and $R_bound$ of neutrino bound states into Eq. [ref], we find that Eq. [ref] requires a minimum mass of $M_bound ≳10^8 M_⊙$ (see also the upper panel of Fig. [ref]), which is similar to the minimum star-forming halo mass estimated in Refs. [ref] .
Probing Long-Range Forces Between Neutrinos with Cosmic Structures · Baryonic structure formation · 0.89
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Unlike collapse in normal Pop III star-forming haloes, which creates quasi-static settling flows [ref] , or in atomically-cooled haloes in which there is at most transonic turbulence, collapse in this halo proceeds on two scales via two, distinct physical processes.
Turbulent Cold Flows Gave Birth to the First Quasars · Introduction · 0.82
Cites it as support 2 papers
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We assumed that the Pop III stars are within 10 AU of the center of the DM halo, as demonstrated by numerous hydrodynamical simulations [ref] which show that Pop III stars form either in isolation, or a few per DM mini-halo, with most of them within the central 10 AU and the most massive ones closest to the center.
Constraining Dark Matter properties with the first generation of stars · Constraining DM properties using Pop III stars · 0.97
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Indeed, numerical simulations predict that predominantly massive stars have formed in the first halos of dark matter to collapse [ref] .
On the Habitability of Our Universe · Section Background · 0.97
Cites it as background 26 papers
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The first suite of calculations [ref] elucidated how Pop III stars formed by redshift $z∼20$ within dark-matter halos with mass $M_halo∼10^6 M_⊙$ [ref] .
Strong Observational Support for the R_h=ct Timeline in the Early Universe · Early Galaxies · 0.86
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The first generation of stars (PopIII) [ref] are believed to have formed inside metal-poor galaxies (sometimes called molecular cooling galaxies or MCGs) hosted by mini halos where gas is cooled by molecular line transitions [ref] .
HERA bound on x-ray luminosity when accounting for population III stars · Introduction · 0.91
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Those objects, also called Population III (or Pop III) stars, can grow to be as massive as $∼100$.[For the interested reader on Pop III stars see: [ref] ] If one insists on this kind of “low seed" BHs, unrealistic sustained super-Eddington accretion rates are required.
UHZ1 and the other three most distant quasars observed: possible evidence for Supermassive Dark Stars · Introduction · 0.84
Discussion
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