The 21 cm signal from the epoch of reionization should be observed within next decade. While a simple statistical detection is expected with Square Kilometre Array (SKA) pathfinders, SKA will hopefully produce full 3D mapping signal. To extract data constraints on parameters describing underlying astrophysical processes, inversion methods must developed. For example, Markov Chain Monte Carlo method has been successfully applied. Here, we test another possible method: artificial neural...

Redshifted 21 cm signal is a promising tool to investigate the state of intergalactic medium (IGM) in cosmic dawn (CD) and epoch reionization (EoR). In our previous work, we studied variance skewness fluctuations give clear interpretation power spectrum found that good indicator when X-ray heating becomes effective. Thus, non-Gaussian feature spatial distribution expected be useful astrophysical effects CD EoR. this paper, order such more detail, focus on bispectrum signal. It brightness...

We perform a Fisher analysis to estimate the expected constraints on epoch-of-reionization (EoR) model parameters (i.e. minimum virial temperature, ionizing efficiency and mean free path of photons) taking into account thermal noise existing telescopes, MWA LOFAR. consider how inclusion 21-cm bispectrum improves compared using power spectrum alone. Assuming that we perfectly remove foregrounds, found bispectrum, which is calculated by 21-cmfast code, can constrain EoR more tightly than since...

The 21cm line brightness temperature brings rich information about Epoch of Reionizaton (EoR) and high-$z$ universe (Cosmic Dawn Dark Age). While the power spectrum is a useful tool to investigate EoR signal statistically, higher-order statistics such as bispectrum are also valuable because expected be highly non-Gaussian. In this paper, we develop formalism calculate contributed from thermal noise taking array configularion telescopes into account, by extending for...

The brightness temperature of the redshifted 21-cm line brings rich information about intergalactic medium (IGM) from cosmic dawn and epoch reionization (EoR). While power spectrum is a useful tool to investigate signal statistically, field highly non-Gaussian inadequate characterize non-Gaussianity. Minkowski functionals (MFs) are promising tools extract features give topological information, such as morphology ionized bubbles. In this work, we study in detail with MFs. To promote...

Although the cosmological paradigm based on cold dark matter and adiabatic, nearly scale-invariant primordial fluctuations is consistent with a wide variety of existing observations, it has yet to be sufficiently tested scales smaller than those massive galaxies, various alternatives have been proposed that differ significantly in consequent small-scale power spectrum (SSPS) large-scale structure. Here we show powerful probe SSPS at $k\ensuremath{\gtrsim}10\text{ }\text{...

The redshifted 21cm line signal from neutral hydrogens is a promising tool to probe the cosmic dawn and epoch of reionization (EoR). Ongoing future low-frequency radio experiments are expected detect its fluctuations, especially through power spectrum. In this paper, we give physical interpretation time evolution spectrum brightness temperature which can be decomposed into dark matter density, spin fraction hydrogen fluctuations. From one-point statistics such as variance skewness, find that...

Redshifted 21cm-line signal from neutral hydrogens in the intergalactic medium (IGM) gives a direct probe of epoch reionization (EoR). In this paper, we investigate potential variance and skewness probability distribution function 21cm brightness temperature for constraining EoR models. These statistical quantities are simple, easy to calculate observed visibility thus suitable early exploration with ongoing telescopes such as Murchison Widefield Array (MWA) LOw Frequency ARray (LOFAR). We...

The ultra-light scalar fields can arise ubiquitously, for instance, as a result of the spontaneous breaking an approximate symmetry such axion and more generally axion-like particles. In addition to particle physics motivations, these particles also play major role in cosmology by contributing dark matter abundance affecting structure formation at sub-Mpc scales. this paper, we propose use 21cm forest observations probe nature matter. much smaller scales than Lyman-$\alpha$ forest, that is,...

Understanding the detailed process of cosmic reionization is one remaining problems in astrophysics and cosmology. Here we construct a model that includes contribution from high-$z$ galaxies active galactic nuclei (AGNs), calculate thermal histories with model. To keep to be general realistic, vary escape fraction ionizing photons, $f_{\rm esc}$, faint-end slope AGN luminosity function at high redshifts, $\alpha_{\rm hz}$, within constraints observed star formation history bright-end UV...

Abstract The dark age of the Universe, when no luminous object existed, ended with birth first stars, galaxies, and black holes. This epoch is called cosmic dawn. Cosmic reionization major transition intergalactic medium in Universe driven by ionizing photons emitted from objects. Although through ages to a milestone our knowledge it not yet sufficient. 21 cm signal, which neutral hydrogen, expected open new window into this epoch. In review paper, we introduce basic physics line how stars...

Abstract In the past several decades, standard cosmological model has been established and its parameters have measured to a high precision, while there are still many fundamental questions in cosmology; such as physics very early universe, origin of cosmic acceleration, nature dark matter. The forthcoming radio telescope, Square Kilometre Array (SKA), which will be world's largest, able open new frontier cosmology one most powerful tools for coming decade. surveys conducted by SKA would...

Cosmic reionization is known to be a major phase transition of the gas in Universe. Since astronomical objects formed early Universe, such as first stars, galaxies and black holes, are expected have caused cosmic reionization, formation history properties closely related process. In spite importance exploring our understandings regarding not sufficient yet. Square Kilometre Array (SKA) next-generation large telescope that will operated next decade. Although several programs telescopes...

ABSTRACT The radio observation of 21 cm-line signal from the epoch reionization (EoR) enables us to explore evolution galaxies and intergalactic medium in early Universe. However, detection imaging are tough due foreground instrumental systematics. In order overcome these obstacles, as a new approach, we propose take cross correlation between observed data images generated distribution Lyman-α emitters (LAEs) through machine learning. create maps LAE distribution, apply conditional...

We study the future prospects of 21 cm forest observations on axionlike dark matter when spontaneous breaking global Peccei-Quinn (PQ) symmetry occurs after inflation. The large isocurvature perturbations order unity sourced from particles can result in enhancement minihalo formation, and subsequent hierarchical structure formation affect abundance whose masses exceed $\mathcal{O}({10}^{4})\text{ }\text{ }{M}_{\ensuremath{\bigodot}}$ relevant for observations. show that are capable probing...

The bubble size distribution of ionized hydrogen regions probes the information about morphology \HII\ bubbles during reionization. Conventionally, can be derived from tomographic imaging data redshifted 21~cm signal epoch reionization, which, however, is observationally challenging even for upcoming large radio interferometer arrays. Given that these interferometers promise to measure power spectrum accurately, we propose a new method, which based on artificial neural networks (ANN),...

In this paper, we propose a novel method to recover the 21cm global signal from power spectrum using artificial neural networks (ANNs). The is crucial for understanding cosmic evolution Dark Ages through Epoch of Reionization (EoR). While interferometers like LOFAR, MWA, HERA, and SKA focus on detecting spectrum, single-dish experiments such as EDGES target signal. Our utilizes ANNs establish connection between these two observables, providing means cross-validate independent line...

We study the effect of relative velocity between dark matter (DM) and baryon on 21-cm forest signals. The DM-baryon arises due to their different evolutions before baryon-photon decoupling epoch, it gives an additional anisotropic pressure that can suppress perturbation growth. It is intriguing scale $k\ensuremath{\sim}\mathcal{O}(10\ensuremath{\sim}{10}^{3})h/\mathrm{Mpc}$ at which power spectrum affected by such a streaming turns out be signal sensitive to. demonstrate absorption line...

Abstract The 21cm signal at epoch of reionization (EoR) should be observed within next decade. We expect that cosmic the EoR provides us both cosmological and astrophysical information. In order to extract fruitful information from observation data, we need develop inversion method. For such a method, introduce artificial neural network (ANN) which is one machine learning techniques. apply ANN problem constrain parameters power spectrum. train architecture with 70 training datasets it 54...

We study the effect of relative velocity between dark matter (DM) and baryon on 21cm forest signals. The DM-baryon arises due to their different evolutions before baryon-photon decoupling epoch it gives an additional anisotropic pressure that can suppress perturbation growth. It is intriguing scales $k\sim {\cal O}(10\sim 10^3)h/\mathrm{Mpc}$ at which power spectrum affected by such a streaming turns out be scale signal sensitive to. demonstrate absorption line abundance decrease more than...