Impact of Ly α heating on the global 21-cm signal from the Cosmic Dawn

Ghara, Raghunath; Mellema, Garrelt

doi:10.1093/mnras/stz3513

Cited by 34 publications

(15 citation statements)

References 60 publications

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“…Such large differential antenna temperatures, however, are not expected at these early times. This is because the high Lyα intensity required for full coupling may heat the gas through Lyα recoils (Ghara & Mellema 2020). Moreover, under conventional star formation rate assumptions in the first galaxies, the Lyα intensity is not expected to be sufficiently strong to produce strong coupling between the IGM spin and kinetic temperatures until z ∼ < 20, with ∆T21−cm −10 mK at z = 30, and decreasing to ∆T21−cm < −200 mK only by z < 20 (eg Barkana & Loeb 2005;Hirata 2006).…”

Section: Discussionmentioning

confidence: 99%

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

Meiksin

Madau

2020

Monthly Notices of the Royal Astronomical Society

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Allowing for enhanced Lyα photon line emission from Population III dominated stellar systems in the first forming galaxies, we show the 21-cm cosmic dawn signal at 10 < $z$ < 30 may substantially differ from standard scenarios. Energy transfer by Lyα photons emerging from galaxies may heat intergalactic gas if H ii regions within galaxies are recombination bound, or cool the gas faster than by adiabatic expansion if reddened by winds internal to the haloes. In some extreme cases, differential 21-cm antenna temperatures near −500 mK may be achieved at 15 < $z$ < 25, similar to the signature detected by the EDGES 21-cm cosmic dawn experiment.

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Section: Discussionmentioning

confidence: 99%

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

Meiksin

Madau

2020

Monthly Notices of the Royal Astronomical Society

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“…We note that in this paper we ignore the (∼ 10 per cent) effect of the CMB heating (Venumadhav et al 2018)a n dt h ee f f e c to fL yα heating (e.g. Chuzhoy & Shapiro 2007;Ghara & Mellema 2019). In our simulations, the effects of ionizing radiation (ultraviolet radiation from stars) are defined by two parameters: the mean free path of ionizing photons, R mfp = 10-70 comoving Mpc, and the ionizing efficiency of sources, ζ , which is tuned to yield the CMB optical depth τ in the range between 0.045 and 0.1.…”

Section: Astrophysical Parametersmentioning

confidence: 99%

Tight constraints on the excess radio background at z = 9.1 from LOFAR

Mondal

Fialkov

Fling

et al. 2020

Monthly Notices of the Royal Astronomical Society

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The ARCADE2 and LWA1 experiments have claimed an excess over the Cosmic Microwave Background (CMB) at low radio frequencies. If the cosmological high-redshift contribution to this radio background is between 0.1% and 22% of the CMB at 1.42 GHz, it could explain the tentative EDGES Low-Band detection of the anomalously deep absorption in the 21-cm signal of neutral hydrogen. We use the upper limit on the 21-cm signal from the Epoch of Reionization (z = 9.1) based on 141 hours of observations with LOFAR to evaluate the contribution of the high redshift Universe to the detected radio background. Marginalizing over astrophysical properties of star-forming halos, we find (at 95% C.L.) that the cosmological radio background can be at most 9.6% of the CMB at 1.42 GHz. This limit rules out strong contribution of the high-redshift Universe to the ARCADE2 and LWA1 measurements. Even though LOFAR places limit on the extra radio background, excess of 0.1 − 9.6% over the CMB (at 1.42 GHz) is still allowed and could explain the EDGES Low-Band detection. We also constrain the thermal and ionization state of the gas at z = 9.1, and put limits on the properties of the first star-forming objects. We find that, in agreement with the limits from EDGES High-Band data, LOFAR data constrain scenarios with inefficient X-ray sources, and cases where the Universe was ionized by stars in massive halos only.

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“…After the first star formation (z ∼ 30), their radiation starts to heat the intergalactic medium (IGM) [52,59,[72][73][74][75][76]. Authors of the Ref.…”

Section: Heating Of the Igm Due To Background Radiationmentioning

confidence: 99%

Constraint on primordial magnetic fields in the light of ARCADE 2 and EDGES observations

Natwariya

2021

Eur. Phys. J. C

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We study the constraints on primordial magnetic fields (PMFs) in the light of the Experiment to Detect the Global Epoch of Reionization Signature (EDGES) low-band observation and Absolute Radiometer for Cosmology, Astrophysics and Diffuse Emission (ARCADE 2). ARCADE 2 observation detected extra-galactic excess radio radiation in the frequency range 3–90 GHz. The enhancement in the radio radiation is also supported by the first station of the Long Wavelength Array (LWA1) in the frequency range 40–80 MHz. The presence of early radiation excess over the cosmic microwave background can not be completely ruled out, and it may explain the EDGES anomaly. In the presence of decaying PMFs, 21 cm differential brightness temperature can modify due to the heating of the gas by decaying magnetic fields, and we can constraint the magnetic fields. For excess radiation fraction ($$A_r$$ A r ) to be LWA1 limit, we show that the upper bound on the present-day magnetic field strength, $$B_0$$ B 0 , on the scale of 1 Mpc is $$\lesssim 3.7$$ ≲ 3.7 nG for spectral index $$n_B=-2.99$$ n B = - 2.99 . While for $$n_B=-1$$ n B = - 1 , we get $$B_0\lesssim 1.1\times 10^{-3}$$ B 0 ≲ 1.1 × 10 - 3 nG. We also discuss the effects of first stars on IGM gas evolution and the allowed value of $$B_0$$ B 0 . For $$A_r$$ A r to be LWA1 limit, we get the upper constraint on magnetic field to be $$B_0(n_B=-2.99)\lesssim 4.9\times 10^{-1}$$ B 0 ( n B = - 2.99 ) ≲ 4.9 × 10 - 1 nG and $$B_0(n_B=-1)\lesssim 3.7\times 10^{-5}$$ B 0 ( n B = - 1 ) ≲ 3.7 × 10 - 5 nG. By decreasing excess radiation fraction below the LWA1 limit, we get a more stringent bound on $$B_0$$ B 0 .

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Impact of Ly α heating on the global 21-cm signal from the Cosmic Dawn

Cited by 34 publications

References 60 publications

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

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

Tight constraints on the excess radio background at z = 9.1 from LOFAR

Constraint on primordial magnetic fields in the light of ARCADE 2 and EDGES observations

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