Lyman–Werner escape fractions from the first galaxies

Schauer, Anna T. P.; Agarwal, Bhaskar; Glover, Simon C. O.; Klessen, Ralf S.; Latif, Muhammad; Mas-Ribas, Lluís; Rydberg, Claes-Erik; Whalen, Daniel J.; Zackrisson, Erik

doi:10.1093/mnras/stx264

Cited by 42 publications

(35 citation statements)

References 65 publications

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“…(1) [52,59,60], and increase the minimum mass M cool that a halo needs to form stars [53,[61][62][63][64]. More relevant to our work, the relative velocities produce a complex phase between the baryons and dark-matter fluctuations, suppressing the matter power spectrum at small scales (k ∼ 20 − 200 Mpc −1 ) in a spatially inhomogeneous way [58,65], which if unaccounted for would appear as a departure from CDM.…”

Section: Velocity-induced Acoustic Oscillationsmentioning

confidence: 89%

Probing the small-scale matter power spectrum with large-scale 21-cm data

2020

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The distribution of matter fluctuations in our universe is key for understanding the nature of dark matter and the physics of the early cosmos. Different observables have been able to map this distribution at large scales, corresponding to wavenumbers k 10 Mpc −1 , but smaller scales remain much less constrained. In this work we study the sensitivity of upcoming measurements of the 21-cm line of neutral hydrogen to the small-scale matter power spectrum. The 21-cm line is a promising tracer of early stellar formation, which took place in small haloes (with masses M ∼ 10 6 − 10 8 M ), formed out of matter overdensities with wavenumbers as large as k ≈ 100 Mpc −1 . Here we forecast how well both the 21-cm global signal, and its fluctuations, could probe the matter power spectrum during cosmic dawn (z = 12−25). In both cases we find that the long-wavelength modes (with k 40 Mpc −1 ) are highly degenerate with astrophysical parameters, whereas the modes with k = (40 − 80) Mpc −1 are more readily observable. This is further illustrated in terms of the principal components of the matter power spectrum, which peak at k ∼ 50 Mpc −1 both for a typical experiment measuring the 21-cm global signal and its fluctuations. We find that, imposing broad priors on astrophysical parameters, a global-signal experiment can measure the amplitude of the matter power spectrum integrated over k = (40−80) Mpc −1 with a precision of tens of percent. A fluctuation experiment, on the other hand, can constrain the power spectrum to a similar accuracy over both the k = (40 − 60) Mpc −1 and (60 − 80) Mpc −1 ranges even without astrophysical priors. The constraints outlined in this work would be able to test the behavior of dark matter at the smallest scales yet measured, for instance probing warm-dark matter masses up to mWDM = 8 keV for the global signal and 14 keV for the 21-cm fluctuations. This could shed light on the nature of dark matter beyond the reach of other cosmic probes.

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Section: Velocity-induced Acoustic Oscillationsmentioning

confidence: 89%

Probing the small-scale matter power spectrum with large-scale 21-cm data

2020

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“…Additionally, for Pop III-forming haloes, the escape fractions of LW photons tend to be much smaller in the near field feedback case (Schauer et al 2015). The LW escape fractions of Pop II-forming regions depends on various factors such as the mass of the halo, the IMF, and the star formation history (Schauer et al 2017a). Capturing this complex interplay of parameters is beyond the scope of this project.…”

Section: Radiative Feedbackmentioning

confidence: 98%

Predicting the locations of possible long-lived low-mass first stars: importance of satellite dwarf galaxies

Magg

Hartwig

Agarwal

et al. 2017

Monthly Notices of the Royal Astronomical Society

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The search for metal-free stars has so far been unsuccessful, proving that if there are surviving stars from the first generation, they are rare, they have been polluted, or we have been looking in the wrong place. To predict the likely location of Population III (Pop III) survivors, we semi-analytically model early star formation in progenitors of Milky Way-like galaxies and their environments. We base our model on merger trees from the high-resolution dark matter only simulation suite Caterpillar. Radiative and chemical feedback are taken into account self-consistently, based on the spatial distribution of the haloes. Our results are consistent with the non-detection of Pop III survivors in the Milky Way today. We find that possible surviving Population III stars are more common in Milky Way satellites than in the main Galaxy. In particular, low mass Milky Way satellites contain a much larger fraction of Pop III stars than the Milky Way. Such nearby, low mass Milky Way satellites are promising targets for future attempts to find Pop III survivors, especially for high-resolution, high signalto-noise spectroscopic observations. We provide the probabilities of finding a Pop III survivor in the red giant branch phase for all known Milky Way satellites to guide future observations.

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“…In the last couple of years the community has made progress in studying both the conventional route to direct collapse, which involves gas inflows in metal-free atomic cooling halos (e.g. Latif et al 2013a;Regan and Haehnelt 2009;Regan et al 2017) and other scenarios, such as the merger-driven model (Mayer et al, 2010;Bonoli et al, 2014;Mayer and Bonoli, 2019), or models whereby colliding streams in proto-halos at very high-z (Hirano et al, 2017) or streaming velocities (Schauer et al, 2017a) play a role in providing favourable conditions. The most conventional route to suppress H 2 cooling has been to invoke nearby sources of Lyman-Werner photons, which can efficiently dissociate H 2 .…”

Section: A Crucial Aspect: Angular Momentum Transport In Protogalaxiesmentioning

confidence: 99%

Formation of the First Stars and Black Holes

et al. 2020

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KeywordsAbstract We review the current status of knowledge concerning the early phases of star formation during cosmic dawn. This includes the first generations of stars forming in the lowest mass dark matter halos in which cooling and condensation of gas with primordial composition is possible at very high redshift (z > 20), namely metal-free Population III stars, and the first generation of massive black holes forming at such early epochs, the socalled black hole seeds. The formation of black hole seeds as end states of the collapse of Population III stars, or via direct collapse scenarios, is discussed. In particular, special emphasis is given to the physics of supermassive stars as potential precursors of direct collapse black holes, in light of recent results of stellar evolution models, and of numerical simulations of the early stages of galaxy formation. Furthermore, we discuss the role of the cosmic radiation produced by the early generation of stars and black holes at high redshift in the process of reionization.

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Lyman–Werner escape fractions from the first galaxies

Cited by 42 publications

References 65 publications

Probing the small-scale matter power spectrum with large-scale 21-cm data

Probing the small-scale matter power spectrum with large-scale 21-cm data

Predicting the locations of possible long-lived low-mass first stars: importance of satellite dwarf galaxies

Formation of the First Stars and Black Holes

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