Constraining Warm Dark Matter and Pop III stars with the Global 21-cm Signal

Hibbard, Joshua J.; Mirocha, Jordan; Rapetti, David; Bassett, Neil; Burns, Jack O.; Tauscher, Keith

doi:10.48550/arxiv.2201.02638

Cited by 2 publications

(2 citation statements)

References 82 publications

(92 reference statements)

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“…Figure 1 shows the cosmic thermal evolution (left panel) and the 21-cm signal (right panel) for the best-fitting values of the seven parameters of the model described above, when the model is fit to the EDGES measurement, assuming a constant 50 mK uncertainty across the frequency band (see also Hills et al 2018;Mirocha & Furlanetto 2019;Chatterjee et al 2021;Hibbard et al 2022). The best-fitting parameter values are listed in Table 1.…”

Section: The 21-cm Absorption Profilementioning

confidence: 99%

Implications of the cosmological 21-cm absorption profile for high-redshift star formation and deep JWST surveys

Mittal,

Kulkarni

2022

Preprint

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Apart from its anomalously large depth, the cosmological 21-cm absorption signal measured by the EDGES collaboration also has a shape that is distinctly different from theoretical predictions. This peculiar shape requires the establishment of a cosmic Ly 𝛼 background within 25 Myr at redshift 𝑧 ∼ 20 and a cosmic X-ray background within 50 Myr at redshift 𝑧 ∼ 15. Models with non-traditional components such as super-adiabatic baryonic cooling or an excess radio background explain the depth of the observed profile, but still conspicuously fail to explain its shape. In this paper, we quantify the requirements imposed by the EDGES measurement on sources of Ly 𝛼 and X-ray photons at cosmic dawn. In extreme cases, the Ly 𝛼 and X-ray emissivities require to be enhanced by up to an order of magnitude relative to traditional models. Furthermore, this enhancement needs to be active only for a short duration. We find that under conventional assumptions for the cosmic star formation density, standard stellar populations are incapable of meeting these conditions. Only highly unusual models of massive metal-free stars seem to provide a possible mechanism. Conversely, if the sources of Ly 𝛼 and X-ray photons are compelled to have standard properties, the EDGES measurement puts strong demands on the cosmic star formation rate density. This provides interesting falsifiable predictions for high-redshift galaxy surveys enabled by JWST. We derive predictions for galaxy UV luminosity functions and number densities, and show that a deep JWST survey with a limiting UV magnitude of 𝑚 UV,lim = 32 would potentially be able to rule out the predictions enforced by the EDGES measurement.

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Section: The 21-cm Absorption Profilementioning

confidence: 99%

Implications of the cosmological 21-cm absorption profile for high-redshift star formation and deep JWST surveys

Mittal,

Kulkarni

2022

Preprint

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“…The first generation of stars, commonly referred to as the population III (Pop III) stars (Bromm & Larson 2004;Klessen 2019), are expected to have a strong effect on the high-redshift IGM, and, thus, the 21-cm signal from cosmic dawn (Cohen et al 2016;Mirocha et al 2018;Mebane et al 2018;Tanaka et al 2018;Schauer et al 2019;Mebane et al 2020;Muñoz et al 2021;Tanaka & Hasegawa 2021;Hibbard et al 2022). It has been shown that the efficiency and rate of star formation for the Pop III stars strongly impact the depth of the 21-cm global signal absorption trough (Yajima & Khochfar 2015;Cohen et al 2018;Mebane et al 2018;Mirocha & Furlanetto 2019;Schauer et al 2019;Chatterjee et al 2020;Muñoz et al 2021;Reis et al 2021a).…”

Section: Introductionmentioning

confidence: 99%

Impact of the Primordial Stellar Initial Mass Function on the 21-cm Signal

Gessey-Jones¹,

Sartorio²,

Fialkov³

et al. 2022

Preprint

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Properties of the first generation of stars (Pop III), such as their initial mass function (IMF), are poorly constrained by observations and have yet to converge between simulations. The cosmological 21-cm signal of neutral hydrogen is predicted to be sensitive to Lyman band photons produced by these stars, thus providing a unique way to probe the first stellar population. In this paper, we investigate the impacts of the Pop III IMF on the cosmic dawn 21-cm signal via the Wouthysen-Field effect, Lyman-Werner feedback, Ly 𝛼 heating, and CMB heating. We calculate the emission spectra of star-forming halos for different IMFs by integrating over individual metal-free stellar spectra, computed from a set of stellar evolution histories and stellar atmospheres, and taking into account variability of the spectra with stellar age. Through this study, we therefore relax two common assumptions: that the zero-age main sequence emission rate of a Pop III star is representative of its lifetime mean emission rate, and that Pop III emission can be treated as instantaneous. Exploring a bottom-heavy, a top-heavy, and intermediate IMFs, we show that variations in the 21-cm signal are driven by stars lighter than 20 M . For the explored models we find maximum relative differences of 68% in the cosmic dawn global 21-cm signal, and 137% between power spectra. Although this impact is modest, precise modelling of the first stars and their evolution is necessary for accurate prediction and interpretation of the 21-cm signal.

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Constraining Warm Dark Matter and Pop III stars with the Global 21-cm Signal

Cited by 2 publications

References 82 publications

Implications of the cosmological 21-cm absorption profile for high-redshift star formation and deep JWST surveys

Implications of the cosmological 21-cm absorption profile for high-redshift star formation and deep JWST surveys

Impact of the Primordial Stellar Initial Mass Function on the 21-cm Signal

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