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Register a new userForecasts on Interacting Dark Energy from 21-cm Angular Power Spectrum with BINGO and SKA observations
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Neutral hydrogen (HI) intensity mapping is a promising technique to probe the large-scale structure of the Universe, improving our understanding on the late-time accelerated expansion. In this work, we first scrutinize how an alternative cosmology, interacting Dark Energy, can affect the 21-cm angular power spectrum relative to the concordance $Lambda$CDM model. We re-derive the 21-cm brightness temperature fluctuation in the context of such interaction and uncover an extra new contribution. Then we estimate the noise level of three upcoming HI intensity mapping surveys, BINGO, SKA1-MID Band$,$1 and Band$,$2, respectively, and employ a Fisher matrix approach to forecast their constraints on the interacting Dark Energy model. We find that while $textit{Planck},$ 2018 maintains its dominion over early-Universe parameter constraints, BINGO and SKA1-MID Band$,$2 put complementary bounding to the latest CMB measurements on dark energy equation of state $w$, the interacting strength $lambda_i$ and the reduced Hubble constant $h$, and SKA1-MID Band$,$1 even outperforms $textit{Planck},$ 2018 in these late-Universe parameter constraints. The expected minimum uncertainties are given by SKA1-MID Band$,$1+$textit{Planck},$: $sim 0.35%$ on $w$, $sim 0.27%$ on $h$, $sim 0.61%$ on HI bias $b_{rm HI}$, and an absolute uncertainty of about $3times10^{-4}$ ($7times10^{-4}$) on $lambda_{1}$ ($lambda_{2}$). Moreover, we quantify the effect of increasing redshift bins and inclusion of redshift-space distortions in updating the constraints. Our results indicate a bright prospect for HI intensity mapping surveys in constraining interacting Dark Energy, whether on their own or further by a joint analysis with other measurements.
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We forecast constraints on cosmological parameters in the interacting dark energy models using the mock data generated for neutral hydrogen intensity mapping (IM) experiments. In this work, we only consider the interacting dark energy models with energy transfer rate $Q=beta Hrho_{rm c}$, and take BINGO, FAST, SKA1-MID, and Tianlai as typical examples of the 21 cm IM experiments. We find that the Tianlai cylinder array will play an important role in constraining the interacting dark energy model. Assuming perfect foreground removal and calibration, and using the Tianlai-alone data, we obtain $sigma(H_0)=0.19$ km s$^{-1}$ Mpc$^{-1}$, $sigma(Omega_{rm m})=0.0033$ and $sigma(sigma_8)=0.0033$ in the I$Lambda$CDM model, which are much better than the results of Planck+optical BAO (i.e. optical galaxy surveys). However, the Tianlai-alone data cannot provide a very tight constraint on the coupling parameter $beta$ compared with Planck+optical BAO, while the Planck+Tianlai data can give a rather tight constraint of $sigma(beta)=0.00023$ due to the parameter degeneracies being well broken by the data combination. In the I$w$CDM model, we obtain $sigma(beta)=0.00079$ and $sigma(w)=0.013$ from Planck+Tianlai. In addition, we also make a detailed comparison among BINGO, FAST, SKA1-MID, and Tianlai in constraining the interacting dark energy models. We show that future 21 cm IM experiments will provide a useful tool for exploring the nature of dark energy and play a significant role in measuring the coupling between dark energy and dark matter.
The 21-cm line of neutral hydrogen (HI) opens a new avenue in our exploration of the Universes structure and evolution. It provides complementary data with different systematics, which aim to improve our current understanding of the $Lambda$CDM model. Among several radio cosmological surveys designed to measure this line, BINGO is a single dish telescope mainly designed to detect Baryon Acoustic Oscillations (BAO) at low redshifts ($0.127 < z < 0.449$). Our goal is to assess the capabilities of the fiducial BINGO setup to constrain the cosmological parameters and analyse the effect of different instrument configurations. We will use the 21-cm angular power spectra to extract information about the HI signal and the Fisher matrix formalism to study BINGO projected constraining power. We use the Phase 1 fiducial configuration of the BINGO telescope to perform our cosmological forecasts. In addition, we investigate the impact of several instrumental setups and different cosmological models. Combining BINGO with Planck temperature and polarization data, we project a $1%$ and a $3%$ precision measurement at $68%$ CL for the Hubble constant and the dark energy (DE) equation of state (EoS), respectively, within the wCDM model. Assuming a CPL parametrization, the EoS parameters have standard deviations given by $sigma_{w_0} = 0.30$ and $sigma_{w_a} = 1.2$. We find that BINGO can also help breaking degeneracies in alternative models, which improves the cosmological constraints significantly. Moreover, we can access information about the HI density and bias, obtaining $sim 8.5%$ and $sim 6%$ precision, respectively, assuming they vary with redshift at three independent bins. The fiducial BINGO configuration will be able to extract significant information from the HI distribution and provide constraints competitive with current and future cosmological surveys. (Abridged)
The light-cone (LC) effect causes the mean as well as the statistical properties of the redshifted 21-cm signal $T_{rm b}(hat{bf n}, u)$ to change with frequency $ u$ (or cosmic time). Consequently, the statistical homogeneity (ergodicity) of the signal along the line of sight (LoS) direction is broken. This is a severe problem particularly during the Epoch of Reionization (EoR) when the mean neutral hydrogen fraction ($bar{x}_{rm HI}$) changes rapidly as the universe evolves. This will also pose complications for large bandwidth observations. These effects imply that the 3D power spectrum $P(k)$ fails to quantify the entire second-order statistics of the signal as it assumes the signal to be ergodic and periodic along the LoS. As a proper alternative to $P(k)$, we use the multi-frequency angular power spectrum (MAPS) ${mathcal C}_{ell}( u_1, u_2)$ which does not assume the signal to be ergodic and periodic along the LoS. Here, we study the prospects for measuring the EoR 21-cm MAPS using future observations with the upcoming SKA-Low. Ignoring any contribution from the foregrounds, we find that the EoR 21-cm MAPS can be measured at a confidence level $ge 5sigma$ at angular scales $ell sim 1300$ for total observation time $t_{rm obs} ge 128,{rm hrs}$ across $sim 44,{rm MHz}$ observational bandwidth. We also quantitatively address the effects of foregrounds on MAPS detectability forecast by avoiding signal contained within the foreground wedge in $(k_perp, k_parallel)$ plane. These results are very relevant for the upcoming large bandwidth EoR experiments as previous predictions were all restricted to individually analyzing the signal over small frequency (or equivalently redshift) intervals.
A recent observation points to an excess in the expected 21-cm brightness temperature from cosmic dawn. In this paper, we present an alternative explanation of this phenomenon, an interaction in the dark sector. Interacting dark energy models have been extensively studied recently and there is a whole variety of such in the literature. Here we particularize to a specific model in order to make explicit the effect of an interaction.
We consider the dark matter (DM) scenarios consisting of the mixture of WIMPs and PBHs and study how much fraction of the total DM can be PBHs. In such scenarios, PBHs can accrete the WIMPs and consequently enhance the heating and ionization in the intergalactic medium due to WIMP annihilations. We demonstrate that the CMB data can give the stringent bounds on the allowed PBH fraction which are comparable or even tighter than those from the gamma ray data depending on the DM masses. For instance, the MCMC likelihood analysis using the Planck CMB data leads to the bound on PBH DM fraction with respect to the total dark matter $f_{rm PBH} lesssim {cal O}( 10^{-10}sim 10^{-8})$ for the WIMP mass $m_{chi}sim {cal O}(10sim 10^3)$ GeV with the conventional DM annihilation cross section $langle sigma v rangle=3 times 10^{-26}~rm cm^3/s $. We also investigate the feasibility of the global 21-cm signal measurement to provide the stringent constraints on the PBH fraction.
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