Cosmic recombination history in light of EDGES measurements of the cosmic dawn 21-cm signal

Datta, Kanan K.; Kundu, Aritra; Paul, Ankit; Bera, Ankita

doi:10.1103/physrevd.102.083502

Cited by 4 publications

(2 citation statements)

References 36 publications

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“…Independent of weak interaction and following the first formation of hydrogen atoms [33,34] we noticed a striking correlation between current Hubble mass and the proposed reference mass unit. It can be expressed as follows.…”

Section: On the Role Of Recombination Temperature In Estimating 200 M...mentioning

confidence: 74%

Weak Interaction Dependent Super Gravity of Galactic Baryon Mass

U.V¹,

Lakshminarayana²

2022

5003

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Considering our light speed growing Planck scale universe, it seems possible to develop a practical model of Hubble-Hawking Universe by using which cosmic temperature and Hubble parameter can be correlated accurately. Without considering galactic dark matter, galactic flat rotation speeds can be addressed with ‘super gravity’ of galactic baryonic mass. In this context, (180 to 200) million solar masses can be considered as a characteristic upper mass limit of ordinary gravity. Considering the proposed current upper mass limit of ordinary gravity as a characteristic weak interaction mass unit, hypothecated galactic dark matter can be quantified. Clearly speaking, weak interaction boosts the gravity of galaxies in proportion to their virtual dark mass as (galactic baryonic mass)3/2 / (200 million solar masses)1/2. Based on cosmic recombination temperature and baryon acoustic bubble radius, upper mass limit of gravity can also be fitted. With further study, dark matter existence and physical properties can be explored.

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Section: On the Role Of Recombination Temperature In Estimating 200 M...mentioning

confidence: 74%

Weak Interaction Dependent Super Gravity of Galactic Baryon Mass

U.V¹,

Lakshminarayana²

2022

5003

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“…This results in higher HI 21-cm optical depth . For example, s are ∼ 3.6 K, 7 K at redshifts = 12 and 17.2 respectively as per the standard scenario if there is no heating (Lewis & Challinor 2007;Seager et al 2000;Datta et al 2020) 1 . This corresponds to the HI optical depth ∼ 0.1 and ∼ 0.08 at the mean HI density ¯ HI .…”

Section: -Cm Signal At Large Optical Depth and Implications Of Edges ...mentioning

confidence: 83%

Large HI optical depth and Redshifted 21-cm signal from cosmic dawn

Datta,

Ghara,

Hoque

et al. 2021

Preprint

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The HI 21-cm optical depth ( ) can be considerably large as the kinetic and spin temperature of the inter-galactic medium(IGM) is expected to be very low during cosmic dawn. It will be particularly higher at regions with HI over-density. We revisit the validity of the widely used linearized equation for estimating the HI 21-cm differential brightness temperature ( ) which assumes << 1 and approximates [1 − exp(− )] as . We consider two scenarios, one without any additional cooling mechanism or radio background ( referred as standard scenario) and the other (referred as excess-cooling scenario) assumes the EDGES like absorption profile and an excess cooling mechanism. We find that given a measured global absorption signal, consistent with the standard(excess-cooling) scenario, the linearized equation overestimates the spin temperature by ∼ 5%(10%). Further, using numerical simulations, we study impact that the large optical depth has on various signal statistics. We observe that the variance, skewness and kurtosis, calculated at simulation resolution (∼ 0.5ℎ −1 Mpc), are over-predicted up to ∼ 30%, 30% and 15% respectively for the standard and up to ∼ 90%, 50% and 50% respectively for the excess-cooling scenario. Moreover, we find that the probability distribution function of is squeezed and becomes more Gaussian in shape if no approximation is made. The spherically averaged HI power spectrum is over predicted by up to ∼ 25% and 80% at all scales for the standard and excess-cooling scenarios respectively.

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Impact of cosmic rays on the global 21-cm signal during cosmic dawn

Bera

Samui

Datta

2022

Monthly Notices of the Royal Astronomical Society

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It is extremely important to understand the processes through which the thermal state of the inter-galactic medium (IGM) evolved in the early universe in order to study the evolution of HI 21-cm signal during cosmic dawn. Here we consider the heating of the IGM due to cosmic ray protons generated by the supernovae from both early Pop III and Pop II stars. The low energy cosmic ray protons from Pop III supernovae can escape from minihalos and heat the IGM via collision and ionization of hydrogen. Furthermore, high energy protons generated in Pop II supernovae can escape the hosting halos and heat the IGM via magnetosonic Alfvén waves. We show that the heating due to these cosmic ray particles can significantly impact the IGM temperature and hence the global 21-cm signal at z ∼ 14 − 18. The depth, location, and duration of the 21-cm absorption profile are highly dependent on the efficiencies of cosmic ray heating. In particular, the EDGES signal can be well fitted by the cosmic ray heating along with the Lyman-α coupling and the dark matter-baryon interaction that we consider to achieve a ‘colder IGM background’. Further, we argue that the properties of cosmic rays and the nature of first generation of stars could be constrained by accurately measuring the global 21-cm absorption signal during the cosmic dawn.

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Cosmic recombination history in light of EDGES measurements of the cosmic dawn 21-cm signal

Cited by 4 publications

References 36 publications

Weak Interaction Dependent Super Gravity of Galactic Baryon Mass

Weak Interaction Dependent Super Gravity of Galactic Baryon Mass

Large HI optical depth and Redshifted 21-cm signal from cosmic dawn

Impact of cosmic rays on the global 21-cm signal during cosmic dawn

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