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Register a new userThe BINGO Project VII: Cosmological Forecasts from 21-cm Intensity Mapping
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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)
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We forecast ability of dedicated 21 cm intensity mapping experiments to constraint primordial non-Gaussianity using power spectrum and bispectrum. We model the signal including the non-linear biasing expansion using a generalized halo model approach. We consider the importance of foreground filtering scale and of the foreground wedge. We find that the current generation intensity mapping experiments like CHIME do not posses sufficient sensitivity to be competitive with the existing limits. On the other hand, upcoming experiments like HIRAX can improve the current constraints and the proposed PUMA experiment can substantially improve them, reaching sensitivities below $sigma (f_{rm NL})<5$ for equilateral and orthogonal configurations and $sigma( f_{rm NL}) < 1$ for the local shape if good foreground control is achieved.
Using the 21 cm line, observed all-sky and across the redshift range from 0 to 5, the large scale structure of the Universe can be mapped in three dimensions. This can be accomplished by studying specific intensity with resolution ~ 10 Mpc, rather than via the usual galaxy redshift survey. The data set can be analyzed to determine Baryon Acoustic Oscillation wavelengths, in order to address the question: What is the nature of Dark Energy? In addition, the study of Large Scale Structure across this range addresses the questions: How does Gravity effect very large objects? and What is the composition our Universe? The same data set can be used to search for and catalog time variable and transient radio sources.
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.
The 21-cm and Lyman Alpha lines are the dominant line-emission spectral features at opposite ends of the spectrum of hydrogen. Each line can be used to create three dimensional intensity maps of large scale structure. The sky brightness at low redshift due to Lyman Alpha emission is estimated to be 0.4 Jy/Steradian, which is brighter than the zodiacal light foreground.
The 21-cm intensity mapping (IM) of neutral hydrogen (HI) is a promising tool to probe the large-scale structures. Sky maps of 21-cm intensities can be highly contaminated by different foregrounds, such as Galactic synchrotron radiation, free-free emission, extragalactic point sources, and atmospheric noise. We here present a model of foreground components and a method of removal, especially to quantify the potential of Five-hundred-meter Aperture Spherical radio Telescope (FAST) for measuring HI IM. We consider 1-year observational time with the survey area of $20,000,{rm deg}^{2}$ to capture significant variations of the foregrounds across both the sky position and angular scales relative to the HI signal. We first simulate the observational sky and then employ the Principal Component Analysis (PCA) foreground separation technique. We show that by including different foregrounds, thermal and $1/f$ noises, the value of the standard deviation between reconstructed 21-cm IM map and the input pure 21-cm signal is $Delta T = 0.034,{rm mK}$, which is well under control. The eigenmode-based analysis shows that the underlying HI eigenmode is just less than $1$ per cent level of the total sky components. By subtracting the PCA cleaned foreground+noise map from the total map, we show that PCA method can recover HI power spectra for FAST with high accuracy.
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