The BINGO project: VII. Cosmological forecasts from 21 cm intensity mapping

Context. The 21 cm line of neutral hydrogen (HI) opens a new avenue in our exploration of the structure and evolution of the Universe. It provides complementary data to the current large-scale structure (LSS) observations with different systematics, and thus it will be used to improve our understanding of the Icold dark matter (ICDM) model. This will ultimately constrain our cosmological models, attack unresolved tensions, and test our cosmological paradigm. Among several radio cosmological surveys designed to measure this line, BINGO is a single-dish telescope mainly designed to detect baryon acoustic oscillations (BAOs) at low redshifts (0.127 < z < 0.449). Aims. Our goal is to assess the fiducial BINGO setup and its capabilities of constraining the cosmological parameters, and to analyze the effect of different instrument configurations. Methods. We used the 21 cm angular power spectra to extract cosmological information about the HI signal and the Fisher matrix formalism to study BINGO's projected constraining power. Results. We used the Phase 1 fiducial configuration of the BINGO telescope to perform our cosmological forecasts. In addition, we investigated the impact of several instrumental setups, taking into account some instrumental systematics, and different cosmological models. Combining BINGO with Planck temperature and polarization data, the projected constraint improves from a 13% and 25% precision measurement at the 68% confidence level with Planck only to 1% and 3% for the Hubble constant and the dark energy (DE) equation of state (EoS), respectively, within the wCDM model. Assuming a Chevallier- Polarski- Linder (CPL) parameterization, the EoS parameters have standard deviations given by w0 = 0.30 and wa = 1.2, which are improvements on the order of 30% with respect to Planck alone. We also compared BINGO's fiducial forecast with future SKA measurements and found that, although it will not provide competitive constraints on the DE EoS, significant information about HI distribution can be acquired. We can access information about the HI density and bias, obtaining 8.5% and 6% precision, respectively, assuming they vary with redshift at three independent bins. BINGO can also help constrain alternative models, such as interacting dark energy and modified gravity models, improving the cosmological constraints significantly. Conclusions. The fiducial BINGO configuration will be able to extract significant cosmological information from the HI distribution and provide constraints competitive with current and future cosmological surveys. It will also help in understanding the HI physics and systematic effects

The BINGO project: V. Further steps in component separation and bispectrum analysis

Context. Observing the neutral hydrogen distribution across the Universe via redshifted 21 cm line intensity mapping constitutes a powerful probe for cosmology. However, the redshifted 21 cm signal is obscured by the foreground emission from our Galaxy and other extragalactic foregrounds. This paper addresses the capabilities of the BINGO survey to separate such signals. Aims. We show that the BINGO instrumental, optical, and simulations setup is suitable for component separation, and that we have the appropriate tools to understand and control foreground residuals. Specifically, this paper looks in detail at the different residuals left over by foreground components, shows that a noise-corrected spectrum is unbiased, and shows that we understand the remaining systematic residuals by analyzing nonzero contributions to the three-point function. Methods. We use the generalized needlet internal linear combination, which we apply to sky simulations of the BINGO experiment for each redshift bin of the survey. We use binned estimates of the bispectrum of the maps to assess foreground residuals left over after component separation in the final map. Results. We present our recovery of the redshifted 21 cm signal from sky simulations of the BINGO experiment, including foreground components. We test the recovery of the 21 cm signal through the angular power spectrum at different redshifts, as well as the recovery of its non-Gaussian distribution through a bispectrum analysis. We find that non-Gaussianities from the original foreground maps can be removed down to, at least, the noise limit of the BINGO survey with such techniques. Conclusions. Our component separation methodology allows us to subtract the foreground contamination in the BINGO channels down to levels below the cosmological signal and the noise, and to reconstruct the 21 cm power spectrum for different redshift bins without significant loss at multipoles 20≲ l ≲ 500. Our bispectrum analysis yields strong tests of the level of the residual foreground contamination in the recovered 21 cm signal, thereby allowing us to both optimize and validate our component separation analysis

The BINGO project: IV. Simulations for mission performance assessment and preliminary component separation steps

Aims. The large-scale distribution of neutral hydrogen (HI) in the Universe is luminous through its 21 cm emission. The goal of the Baryon Acoustic Oscillations from Integrated Neutral Gas Observations (BINGO) radio telescope is to detect baryon acoustic oscillations at radio frequencies through 21 cm intensity mapping (IM). The telescope will span the redshift range 0.127<z<0.449 with an instantaneous field-of-view of 14.75 - 6.0. Methods. In this work we investigate different constructive and operational scenarios of the instrument by generating sky maps as they would be produced by the instrument. In doing this we use a set of end-to-end IM mission simulations. The maps will additionally be used to evaluate the efficiency of a component separation method (GNILC). Results. We have simulated the kind of data that would be produced in a single-dish IM experiment such as BINGO. According to the results obtained, we have optimized the focal plane design of the telescope. In addition, the application of the GNILC method on simulated data shows that it is feasible to extract the cosmological signal across a wide range of multipoles and redshifts. The results are comparable with the standard principal component analysis method

The BINGO Project: III. Optical design and optimization of the focal plane

Context. The Baryon Acoustic Oscillations from Integrated Neutral Gas Observations (BINGO) telescope was designed to measure the fluctuations of the 21 cm radiation arising from the hyperfine transition of neutral hydrogen. It is also aimed at measuring the baryon acoustic oscillations (BAO) from such fluctuations, thereby serving as a pathfinder to future, deeper intensity mapping surveys. The requirements for the Phase 1 of the projects consider a large reflector system (two 40 m-class dishes in a crossed-Dragone configuration) illuminating a focal plane with 28 horns to measure the sky, with two circular polarizations in a drift scan mode to produce measurements of the radiation in intensity (I) as well as the circular (V) polarization. Aims. In this paper, we present the optical design for the instrument. We describe the optical arrangement of the horns in the focal plane to produce a homogeneous and well-sampled map after the end of Phase 1, as well as the intensity and polarization properties of the beams. Our analysis provides an optimal model for the location of the horns in the focal plane, producing a homogeneous and Nyquist-sampled map after the nominal survey time. Methods. We used the GRASP package to model the focal plane arrangement and performed several optimization tasks to arrive at the current configuration, including an estimation of the sidelobes corresponding to the diffraction patterns of the two mirrors. The final model for the focal plane was defined through a combination of neural network and other direct optimization methods. Results. We arrived at an optimal configuration for the optical system that includes the focal plane positioning and the beam behavior of the instrument. We present an estimate of the expected sidelobes both for intensity and polarization, as well as the effect of band averaging on the final sidelobes, as well as an estimation of the cross-polarization leakage for the final configuration. Conclusions. We conclude that the chosen optical design meets the requirements for the project in terms of polarization purity and area coverage as well as a homogeneity of coverage so that BINGO can perform a successful BAO experiment. We further conclude that the requirements on the placement and rms error on the mirrors are also achievable so that a successful experiment can be conducted

The BINGO project: II. Instrument description

Context. The measurement of diffuse 21-cm radiation from the hyperfine transition of neutral hydrogen (Hi signal) in different redshifts is an important tool for modern cosmology. However, detecting this faint signal with non-cryogenic receivers in single-dish telescopes is a challenging task. The BINGO (Baryon Acoustic Oscillations from Integrated Neutral Gas Observations) radio telescope is an instrument designed to detect baryonic acoustic oscillations (BAOs) in the cosmological Hi signal, in the redshift interval 0:127 ≤ z ≤ 0:449. Aims. This paper describes the BINGO radio telescope, including the current status of the optics, receiver, observational strategy, calibration, and the site. Methods. BINGO has been carefully designed to minimize systematics, being a transit instrument with no moving dishes and 28 horns operating in the frequency range 980 ≤ v ≤ 1260 MHz. Comprehensive laboratory tests were conducted for many of the BINGO subsystems and the prototypes of the receiver chain, horn, polarizer, magic tees, and transitions have been successfully tested between 2018-2020. The survey was designed to cover ∼13% of the sky, with the primary mirror pointing at declination δ = -15°. The telescope will see an instantaneous declination strip of 14:75. Results. The results of the prototype tests closely meet those obtained during the modeling process, suggesting BINGO will perform according to our expectations. After one year of observations with a 60% duty cycle and 28 horns, BINGO should achieve an expected sensitivity of 102μK per 9.33MHz frequency channel, one polarization, and be able to measure the Hi power spectrum in a competitive time frame

The BINGO project: I. Baryon acoustic oscillations from integrated neutral gas observations

Context. Observations of the redshifted 21-cm line of neutral hydrogen (HI) are a new and powerful window of observation that offers us the possibility to map the spatial distribution of cosmic HI and learn about cosmology. Baryon Acoustic Oscillations from Integrated Neutral Gas Observations (BINGO) is a new unique radio telescope designed to be one of the first to probe baryon acoustic oscillations (BAO) at radio frequencies. Aims. BINGO has two science goals: cosmology and astrophysics. Cosmology is the main science goal and the driver for BINGO's design and strategy. The key of BINGO is to detect the low redshift BAO to put strong constraints on the dark sector models and test the ICDM (cold dark matter) model. Given the versatility of the BINGO telescope, a secondary goal is astrophysics, where BINGO can help discover and study fast radio bursts (FRB) and other transients, as well as study Galactic and extragalactic science. In this paper, we introduce the latest progress of the BINGO project, its science goals, describing the scientific potential of the project for each goal and the new developments obtained by the collaboration. Methods. BINGO is a single dish transit telescope that will measure the BAO at low-z by making a 3D map of the HI distribution through the technique of intensity mapping over a large area of the sky. In order to achieve the project's goals, a science strategy and a specific pipeline for cleaning and analyzing the produced maps and mock maps was developed by the BINGO team, which we generally summarize here. Results. We introduce the BINGO project and its science goals and give a general summary of recent developments in construction, science potential, and pipeline development obtained by the BINGO Collaboration in the past few years. We show that BINGO will be able to obtain competitive constraints for the dark sector. It also has the potential to discover several FRBs in the southern hemisphere. The capacity of BINGO in obtaining information from 21-cm is also tested in the pipeline introduced here. Following these developments, the construction and observational strategies of BINGO have been defined. Conclusions. There is still no measurement of the BAO in radio, and studying cosmology in this new window of observations is one of the most promising advances in the field. The BINGO project is a radio telescope that has the goal to be one of the first to perform this measurement and it is currently being built in the northeast of Brazil. This paper is the first of a series of papers that describe in detail each part of the development of the BINGO project

Multistrange baryon elliptic flow in Au plus Au collisions at root(NN)-N-S=200 GeV

We report on the first measurement of elliptic flow nu(2)(p(T)) of multistrange baryons Xi(-)+Xi(+) and Omega(-)+Omega(+) in heavy-ion collisions. In minimum-bias Au+Au collisions at root s(NN)=200 GeV, a significant amount of elliptic flow, comparable to other nonstrange baryons, is observed for multistrange baryons which are expected to be particularly sensitive to the dynamics of the partonic stage of heavy-ion collisions. The p(T) dependence of nu(2) of the multistrange baryons confirms the number of constituent quark scaling previously observed for lighter hadrons. These results support the idea that a substantial fraction of the observed collective motion is developed at the early partonic stage in ultrarelativistic nuclear collisions at the Relativistic Heavy Ion Collider

BEYONDPLANCK

End-to-end simulations play a key role in the analysis of any high-sensitivity cosmic microwave background (CMB) experiment, providing high-fidelity systematic error propagation capabilities that are unmatched by any other means. In this paper, we address an important issue regarding such simulations, namely, how to define the inputs in terms of sky model and instrument parameters. These may either be taken as a constrained realization derived from the data or as a random realization independent from the data. We refer to these as posterior and prior simulations, respectively. We show that the two options lead to significantly different correlation structures, as prior simulations (contrary to posterior simulations) effectively include cosmic variance, but they exclude realization-specific correlations from non-linear degeneracies. Consequently, they quantify fundamentally different types of uncertainties. We argue that as a result, they also have different and complementary scientific uses, even if this dichotomy is not absolute. In particular, posterior simulations are in general more convenient for parameter estimation studies, while prior simulations are generally more convenient for model testing. Before BEYONDPLANCK, most pipelines used a mix of constrained and random inputs and applied the same hybrid simulations for all applications, even though the statistical justification for this is not always evident. BEYONDPLANCK represents the first end-to-end CMB simulation framework that is able to generate both types of simulations and these new capabilities have brought this topic to the forefront. The BEYONDPLANCK posterior simulations and their uses are described extensively in a suite of companion papers. In this work, we consider one important applications of the corresponding prior simulations, namely, code validation. Specifically, we generated a set of one-year LFI 30 GHz prior simulations with known inputs and we used these to validate the core low-level BEYONDPLANCK algorithms dealing with gain estimation, correlated noise estimation, and mapmaking

Directed flow in Au+Au collisions at SNN\sqrt{{^S}NN} =62.4 GeV

We present the directed flow (v1) measured in Au+Au collisions at $\sqrt((^S)NN)$=62.4 GeV in the midpseudorapidity region |\eta|<1.3 and in the forward pseudorapidity region 2.5<|\eta|<4.0. The results are obtained using the three-particle cumulant method, the event plane method with mixed harmonics, and for the first time at the Relativistic Heavy Ion Collider, the standard method with the event plane reconstructed from spectator neutrons. Results from all three methods are in good agreement. Over the pseudorapidity range studied, charged particle directed flow is in the direction opposite to that of fragmentation neutrons