The impact of Lyα emission line heating and cooling on the cosmic dawn 21-cm signal

Meiksin, Avery; Madau, Piero

doi:10.1093/mnras/staa3830

Cited by 5 publications

(1 citation statement)

References 55 publications

(96 reference statements)

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“…On the other hand, there have been proposed explanations based on astrophysical agents. One is the possible non-previously accounted effects of the Lyα radiative background (Madau 2018;Kaurov et al 2018;Meiksin & Madau 2021). Other astrophysical explanations are based on an additional CRB of astrophysical origin that boosts the HI absorption (Bowman et al 2018a;Feng & Holder 2018;Chatterjee et al 2020).…”

Section: Possible Explanations Of the Onset Of The Edges Absorptionmentioning

confidence: 99%

Black holes at cosmic dawn in the redshifted 21cm signal of HI

Mirabel

Rodríguez

2022

New Astronomy Reviews

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Section: Possible Explanations Of the Onset Of The Edges Absorptionmentioning

confidence: 99%

Black holes at cosmic dawn in the redshifted 21cm signal of HI

Mirabel

Rodríguez

2022

New Astronomy Reviews

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The subtlety of Ly α photons: changing the expected range of the 21-cm signal

Reis

Fialkov

Barkana

2021

Monthly Notices of the Royal Astronomical Society

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We present the evolution of the 21-cm signal from cosmic dawn and the epoch of reionization (EoR) in an upgraded model including three subtle effects of Ly α radiation: Ly α heating, CMB heating (mediated by Ly α photons), and multiple scattering of Ly α photons. Taking these effects into account we explore a wide range of astrophysical models and quantify the impact of these processes on the global 21-cm signal and its power spectrum. We find that Ly α heating raises the gas temperature by up to $\mathcal {O}(100)$ degrees (CMB heating adds a few more degrees) in models with weak X-ray heating, thus suppressing the predicted 21-cm signals. Varying the astrophysical parameters broadly in an attempt to cover the full plausible range of models, we find that in the upgraded model the absorption trough of the global signal reaches a lowest possible floor of −165 mK at redshifts z ≈ 15 − 19. This is in contrast with the predictions for a pure adiabatically cooling Universe, for which the deepest possible absorption is a monotonically decreasing function of cosmic time and is −178 mK at z = 19 and −216 mK at z = 15, dropping to even lower values at lower redshifts. With Ly α and CMB heating included we also observe a strong suppression in the low-redshift power spectra, with the maximum possible power (evaluated over the ensemble of models) attenuated by a factor of 6.6 at z = 9 and k = 0.1 Mpc−1. Finally, we find that at high redshifts corresponding to cosmic dawn, the multiple scattering of Ly α photons leads to an amplification of the power spectrum by a factor of ∼2 − 3 in all models.

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Introducing SPHINX-MHD: the impact of primordial magnetic fields on the first galaxies, reionization, and the global 21-cm signal

Katz

Martin-Alvarez²,

Rosdahl

et al. 2021

Monthly Notices of the Royal Astronomical Society

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We present the first results from SPHINX-MHD, a suite of cosmological radiation-magnetohydrodynamics simulations designed to study the impact of primordial magnetic fields (PMFs) on galaxy formation and the evolution of the intergalactic medium (IGM) during the epoch of reionization. The simulations are among the first to employ multi-frequency, on-the-fly radiation transfer and constrained transport ideal MHD in a cosmological context to simultaneously model the inhomogeneous process of reionization as well as the growth of primordial magnetic fields. We run a series of (5 cMpc)3 cosmological volumes, varying both the strength of the seed magnetic field and its spectral index. We find that PMFs with a spectral index (nB) and a comoving amplitude (B0) that have $n_B > -0.562\log _{10}\left(\frac{B_0}{1{\rm n}G}\right) - 3.35$ produce electron optical depths (τe) that are inconsistent with CMB constraints due to the unrealistically early collapse of low-mass dwarf galaxies. For nB ≥ −2.9, our constraints are considerably tighter than the ∼nG constraints from Planck. PMFs that do not satisfy our constraints have little impact on the reionization history or the shape of the UV luminosity function. Likewise, detecting changes in the Lyα forest due to PMFs will be challenging because photoionisation and photoheating efficiently smooth the density field. However, we find that the first absorption feature in the global 21cm signal is a particularly sensitive indicator of the properties of the PMFs, even for those that satisfy our τe constraint. Furthermore, strong PMFs can marginally increase the escape of LyC photons by up to 25 per cent and shrink the effective radii of galaxies by $\sim 44{{\ \rm per\ cent}}$ which could increase the completeness fraction of galaxy surveys. Finally, our simulations show that surveys with a magnitude limit of ${\rm M_{UV,1500\mathring{\rm A}}=-13}$ can probe the sources that provide the majority of photons for reionization out to z = 12.

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The impact of Lyα emission line heating and cooling on the cosmic dawn 21-cm signal

Cited by 5 publications

References 55 publications

Black holes at cosmic dawn in the redshifted 21cm signal of HI

Black holes at cosmic dawn in the redshifted 21cm signal of HI

The subtlety of Ly α photons: changing the expected range of the 21-cm signal

Introducing SPHINX-MHD: the impact of primordial magnetic fields on the first galaxies, reionization, and the global 21-cm signal

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