Large-scale Structure Observations Research Articles

The BINGO project

Context. The 21 cm line of neutral hydrogen (H I) 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 Λ cold dark matter (ΛCDM) 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 H I 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 σw0 = 0.30 and σwa = 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 H I distribution can be acquired. We can access information about the H I 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 H I distribution and provide constraints competitive with current and future cosmological surveys. It will also help in understanding the H I physics and systematic effects.

The halo model with beyond-linear halo bias: unbiasing cosmological constraints from galaxy–galaxy lensing and clustering

ABSTRACT We determine the error introduced in a joint halo model analysis of galaxy–galaxy lensing and galaxy clustering observables when adopting the standard approximation of linear halo bias. Considering the Kilo-Degree Survey, we forecast that ignoring the non-linear halo bias would result in up to 5σ offsets in the recovered cosmological parameters describing structure growth, S8, and the matter density parameter, Ωm. We include the scales $10^{-1.3}\lt r_{\rm {p}} \ / h^{-1}\, \mathrm{Mpc}\lt 10$ in the data vector, and the direction of these offsets are shown to depend on the freedom afforded to the halo model through other nuisance parameters. We conclude that a beyond-linear halo bias correction must therefore be included in future cosmological halo model analyses of large-scale structure observables on non-linear scales.

Symmetry of Cosmological Observables, a Mirror World Dark Sector, and the Hubble Constant.

We find that a uniform scaling of the gravitational free-fall rates and photon-electron scattering rate leaves most dimensionless cosmological observables nearly invariant. This result opens up a new approach to reconciling cosmic microwave background and large-scale structure observations with high values of the Hubble constant H_{0}: Find a cosmological model in which the scaling transformation can be realized without violating any measurements of quantities not protected by the symmetry. A "mirror world" dark sector allows for effective scaling of the gravitational free-fall rates while respecting the measured mean photon density today. Further model building might bring consistency with the two constraints not yet satisfied: the inferred primordial abundances of deuterium and helium.

Cosmology of an axion-like majoron

We propose a singlet majoron model that defines an inverse seesaw mechanism in the ν sector. The majoron ϕ has a mass mϕ ≈ 0.5 eV and a coupling to the τ lepton similar to the one to neutrinos. In the early universe it is initially in thermal equilibrium, then it decouples at T ≈ 500 GeV and contributes with just ΔN eff = 0.026 during BBN. At T = 26 keV (final stages of BBN) a primordial magnetic field induces resonant γ ⟷ ϕ oscillations that transfer 6% of the photon energy into majorons, implying ΔN eff = 0.55 and a 4.7% increase in the baryon to photon ratio. At T ≈ mϕ the majoron enters in thermal contact with the heaviest neutrino and it finally decays into νν̅ pairs near recombination, setting ΔN eff = 0.85. The boost in the expansion rate at later times may relax the Hubble tension (we obtain H 0 = (71.4 ± 0.5) km/s/Mpc), while the processes νν̅ ⟷ ϕ suppress the free streaming of these particles and make the model consistent with large scale structure observations. Its lifetime and the fact that it decays into neutrinos instead of photons lets this axion-like majoron avoid the strong bounds that affect other axion-like particles of similar mass and coupling to photons.

New Roads to the Small-scale Universe: Measurements of the Clustering of Matter with the High-redshift UV Galaxy Luminosity Function

Abstract The epochs of cosmic dawn and reionization present promising avenues for understanding the role of dark matter (DM) in our cosmos. The first galaxies that populated the universe during these eras resided in DM halos that were much less massive than their counterparts today. Consequently, observations of such galaxies can provide us with a handle on the clustering of DM in an otherwise currently inaccessible regime. In this work, we use high-redshift UV galaxy luminosity function (UV LF) data from the Hubble Space Telescope to study the clustering properties of DM at small scales. In particular, we present new measurements of the matter power spectrum at wavenumbers 0.5 Mpc−1 < k < 10 Mpc−1 to roughly 30% precision, obtained after marginalizing over the unknown astrophysics. These new data points cover the uncharted redshift range 4 ≤ z ≤ 10 and encompass scales beyond those probed by cosmic microwave background and large-scale structure observations. This work establishes the UV LF as a powerful tool to probe the nature of DM in a different regime than other cosmological and astrophysical data sets.

Strong lensing systems and galaxy cluster observations as probe to the cosmic distance duality relation

In this paper, we use large scale structure observations to test the redshift dependence of cosmic distance duality relation (CDDR), D_mathrm{L}(1+z)^{-2}/D_mathrm{A}=eta (z), with D_mathrm{L} and D_mathrm{A}, being the luminosity and angular diameter distances, respectively. In order to perform the test, the following data set are considered: strong lensing systems and galaxy cluster measurements (gas mass fractions). No specific cosmological model is adopted, only a flat universe is assumed. By considering two eta (z) parametrizations, It is observed that the CDDR remain redshift independent within 1.5sigma which is in full agreement with other recent tests involving cosmological data. It is worth to comment that our results are independent of the baryon budget of galaxy clusters.

Mass assembly history of dark matter haloes in the light of H0 tension

ABSTRACT The Hubble tension may introduce a new course of action to revise the standard Lambda cold dark matter (ΛCDM) model to unravel dark energy and dark matter physics. The Hubble parameter can be reconstructed by late-time observations of the background evolution model independently. We relate the reconstructed Hubble parameter to the structure formation and large-scale structure observables in this work. We use excursion set theory to calculate the number density of dark matter haloes and the mass function of progenitors. We obtain results for both the Markov and non-Markov extensions of excursion set theory in the context of spherical and ellipsoidal collapse. We show that the number density of dark matter haloes in the reconstructed model has ∼2σ difference in comparison with the Planck 2018 ΛCDM in the mass range M ≳ 1012 M⊙. We also compare the dark matter halo progenitor mass function with the pair-galaxy statistics and their mass assembly history from observational data of the Hubble Space Telescope Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey. Due to complications in distinguishing the ratio of accretion and merger in mass assembly, our result on the pair fraction is for illustration only. However, the ∼5 times more accurate observations will be promising for distinguishing the reconstructed model and the Planck 2018 ΛCDM.

Mixed dark matter: matter power spectrum and halo mass function

We investigate and quantify the impact of mixed (cold and warm) dark matter models on large-scale structure observables. In this scenario, dark matter comes in two phases, a cold one (CDM) and a warm one (WDM): the presence of the latter causes a suppression in the matter power spectrum which is allowed by current constraints and may be detected in present-day and upcoming surveys. We run a large set of N-body simulations in order to build an efficient and accurate emulator to predict the aforementioned suppression with percent precision over a wide range of values for the WDM mass, Mwdm, and its fraction with respect to the totality of dark matter, fwdm. The suppression in the matter power spectrum is found to be independent of changes in the cosmological parameters at the 2% level for k≲ 10 h/Mpc and z≤ 3.5. In the same ranges, by applying a baryonification procedure on both ΛCDM and CWDM simulations to account for the effect of feedback, we find a similar level of agreement between the two scenarios. We examine the impact that such suppression has on weak lensing and angular galaxy clustering power spectra. Finally, we discuss the impact of mixed dark matter on the shape of the halo mass function and which analytical prescription yields the best agreement with simulations. We provide the reader with an application to galaxy cluster number counts.

The density distributions of cosmic structures: impact of the local environment on weak-lensing convergence

ABSTRACT Whilst the underlying assumption of the Friedman-Lemaître-Robertson-Walker (FLRW) cosmological model is that matter is homogeneously distributed throughout the universe, gravitational influences over the life of the universe have resulted in mass clustered on a range of scales. Hence we expect that, in our inhomogeneous Universe, the view of an observer will be influenced by the location and local environment. Here, we analyse the one-point probability distribution functions and angular power spectra of weak-lensing (WL) convergence and magnification numerically to investigate the influence of our local environment on WL statistics in relativistic N-body simulations. To achieve this, we numerically solve the null geodesic equations which describe the propagation of light bundles backwards in time from today, and develop a ray-tracing algorithm, and from these calculate various WL properties. Our findings demonstrate how cosmological observations of large-scale structure through WL can be impacted by the locality of the observer. We also calculate the constraints on the cosmological parameters as a function of redshift from the theoretical and numerical study of the angular power spectrum of WL convergence. This study concludes the minimal redshift for the constraint on the parameter Ωm (H0) is $z$ ∼ 0.2 ($z$ ∼ 0.6) beyond which the local environment’s effect is negligible and the data from WL surveys are more meaningful above that redshift. The outcomes of this study will have direct consequences for future surveys, where per cent-level-precision is necessary.

CARPool Covariance: Fast, unbiased covariance estimation for large-scale structure observables

Abstract The covariance matrix $\boldsymbol{\Sigma }$ of non-linear clustering statistics that are measured in current and upcoming surveys is of fundamental interest for comparing cosmological theory and data and a crucial ingredient for the likelihood approximations underlying widely used parameter inference and forecasting methods. The extreme number of simulations needed to estimate $\boldsymbol{\Sigma }$ to sufficient accuracy poses a severe challenge. Approximating $\boldsymbol{\Sigma }$ using inexpensive but biased surrogates introduces model error with respect to full simulations, especially in the non-linear regime of structure growth. To address this problem we develop a matrix generalization of Convergence Acceleration by Regression and Pooling (CARPool) to combine a small number of simulations with fast surrogates and obtain low-noise estimates of $\boldsymbol{\Sigma }$ that are unbiased by construction. Our numerical examples use CARPool to combine GADGET-III N-body simulations with fast surrogates computed using COmoving Lagrangian Acceleration (COLA). Even at the challenging redshift z = 0.5, we find variance reductions of at least $\mathcal {O}(10^1)$ and up to $\mathcal {O}(10^4)$ for the elements of the matter power spectrum covariance matrix on scales 8.9 × 10−3 < kmax < 1.0 hMpc−1. We demonstrate comparable performance for the covariance of the matter bispectrum, the matter correlation function and probability density function of the matter density field. We compare eigenvalues, likelihoods, and Fisher matrices computed using the CARPool covariance estimate with the standard sample covariance and generally find considerable improvement except in cases where $\boldsymbol{\Sigma }$ is severely ill-conditioned.

Galaxy assembly bias and large-scale distribution: a comparison between IllustrisTNG and a semi-analytic model

ABSTRACT In this work, we compare large scale structure observables for stellar mass selected samples at z = 0, as predicted by two galaxy models, the hydrodynamical simulation IllustrisTNG and the Santa-Cruz semi-analytic model (SC-SAM). Although both models have been independently calibrated to match observations, rather than each other, we find good agreement between the two models for two-point clustering and galaxy assembly bias signatures. The models also show a qualitatively similar response of occupancy and clustering to secondary halo parameters other than mass, such as formation history and concentration, although with some quantitative differences. Thus, our results demonstrate that the galaxy–halo relationships in SC-SAM and TNG are quite similar to first order. However, we also find areas in which the models differ. For example, we note a strong correlation between halo gas content and environment in TNG, which is lacking in the SC-SAM, as well as differences in the occupancy predictions for low-mass haloes. Moreover, we show that higher order statistics, such as cumulants of the density field, help us to accurately describe the galaxy distribution and discriminate between models that show degenerate behaviour for two-point statistics. Our results suggest that SAMs are a promising cost-effective and intuitive method for generating mock catalogues for next generation cosmological surveys.

Constraints on electromagnetic form factors of sub-GeV dark matter from the cosmic microwave background anisotropy

We consider dark matter which has nonzero electromagnetic form factors like electric/magnetic dipole moments and anapole moment for fermionic dark matter and Rayleigh form factor for scalar dark matter. We consider dark matter mass ${m}_{\ensuremath{\chi}}>\mathcal{O}(\mathrm{MeV})$ and put constraints on their mass and electromagnetic couplings from cosmic microwave background (CMB) and large scale structure (LSS) observations. Fermionic dark matter with nonzero electromagnetic form factors can annihilate to ${e}^{+}{e}^{\ensuremath{-}}$ and scalar dark matter can annihilate to $2\ensuremath{\gamma}$ at the time of recombination and distort the CMB. We analyze dark matter with multipole moments with Planck and baryon acoustic oscillations (BAO) observations. We find upper bounds on anapole moment ${g}_{A}<7.163\ifmmode\times\else\texttimes\fi{}{10}^{3}\text{ }\text{ }{\mathrm{GeV}}^{\ensuremath{-}2}$, electric dipole moment $\mathcal{D}<7.978\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}\text{ }\text{ }e\text{ }\mathrm{cm}$, magnetic dipole moment $\ensuremath{\mu}<2.959\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}7}{\ensuremath{\mu}}_{B}$, and the bound on Rayleigh form factor of dark matter is ${g}_{4}/{\mathrm{\ensuremath{\Lambda}}}_{4}^{2}<1.085\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}2}\text{ }\text{ }{\mathrm{GeV}}^{\ensuremath{-}2}$ with 95% C.L.

Digital image correlation with topology-based matching algorithm on dots pattern and its application in large deformation measurement of nitrile–butadiene rubber

Digital image correlation (DIC) has inherent limitations in large deformation measurement, such as speckle pattern decorrelation and high computation time cost. A new dots pattern with fixed size and randomly distributed dots is devised for DIC, rather than the traditional grayscale speckle pattern. Topology-based matching correlation (TMC) based on dots pattern is proposed, in which topology connectivity property is used in correlation calculation for images before and after deformation. Experiments on simulated tensile deformation with up to 300% elongation and nitrile-butadiene rubber tensile tests with 260% elongation were designed and results showed that, compared with the incremental-DIC method, the proposed TMC based DIC (TMC-DIC) method could correctly obtain large deformation with no need of updating reference image, less time consumption and smaller errors. The proposed method also has advantages in the applications like real time deformation observation or deformation measurement of large-scale structure.

Gravitational lens time-delay as a probe of a possible time variation of the fine-structure constant

A new method based on large scale structure observations is proposed to probe a possible temporal variation of the fine-structure constant (alpha ). Our analyses are based on time-delay of Strong Gravitational Lensing and Type Ia Supernovae observations. By considering the runaway dilaton scenario, where the cosmological temporal evolution of the fine-structure constant is given by frac{Delta alpha }{alpha } approx -gamma ln {(1+z)}, we obtain limits on the physical properties parameter of the model (gamma ) at the level 10^{-2} (1sigma ). Although our limits are less restrictive than those obtained by quasar spectroscopy, the approach presented here provides new bounds on the possibility of frac{Delta alpha }{alpha } ne 0 at a different range of redshifts.

Observations of large-scale coherent structures in gravity currents: implications for flow dynamics

Density driven flows, also known as gravity currents, comprise a head, body, and tail. Yet whilst the body typically forms the largest part of such flows, its structure remains poorly understood. In this work, experimental data gathered using particle image velocimetry enables the instantaneous, whole-field dynamics of constant-influx solute-based gravity currents to be resolved. While averaged turbulent kinetic energy profiles are comparable to previous work, the instantaneous data sets reveal significant temporal variation, with velocity measurements indicating large-scale wave-like motions within the body. Spectral analysis and dynamic mode decomposition, of streamwise and vertical velocity, are used to identify the frequencies and structures of the dominant motions within the flow. By considering an idealised theoretical density profile, it is suggested that these structures may be internal gravity waves that form a critical layer within the flow located at the height of the maximum internal velocity. Irreversible internal wave breaking that has been postulated to occur at this critical layer suggests formation of internal eddy transport barriers, demonstrating that new dynamic models of turbulent mixing in gravity currents are needed.Graphic abstract

Early dark energy resolution to the Hubble tension in light of weak lensing surveys and lensing anomalies

A constant early dark energy (EDE) component contributing a fraction ${f}_{\mathrm{EDE}}({z}_{c})\ensuremath{\sim}10%$ of the energy density of the universe around ${z}_{c}\ensuremath{\simeq}3500$ and diluting as or faster than radiation afterwards, can provide a simple resolution to the Hubble tension, the $\ensuremath{\sim}5\ensuremath{\sigma}$ discrepancy---in the $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$ context---between the ${H}_{0}$ value derived from early- and late-universe observations. However, it has been pointed out that including Large-Scale Structure (LSS) data, which are in $\ensuremath{\sim}3\ensuremath{\sigma}$ tension with $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$ and EDE cosmologies, might break some parameter degeneracy and alter these conclusions. We reassess the viability of the EDE against a host of high- and low-redshift measurements, by combining LSS observations from recent weak lensing (WL) surveys with CMB, baryon acoustic oscillation (BAO), growth function (FS) and Supernova Ia (SNIa) data. Introducing a model whose only parameter is ${f}_{\mathrm{EDE}}({z}_{c})$, we report in agreement with past work a $\ensuremath{\sim}2\ensuremath{\sigma}$ preference for nonzero ${f}_{\mathrm{EDE}}({z}_{c})$ from Planck CMB data alone, while the tension with the local ${H}_{0}$ measurement from sh0es is reduced below $2\ensuremath{\sigma}$. Adding BAO, FS and SNIa does not affect this conclusion, while the inclusion of a prior on ${H}_{0}$ from sh0es increase the preference for EDE over $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$ to the $\ensuremath{\sim}3.6\ensuremath{\sigma}$ level. After checking the EDE nonlinear matter power spectrum as predicted by standard semi-analytical algorithms via a dedicated set of $N$-body simulations, we test the 1-parameter EDE cosmology against WL data. We find that it does not significantly worsen the fit to the ${S}_{8}$ measurement as compared to $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$, and that current WL observations do not exclude the EDE resolution to the Hubble tension. We also caution against the interpretation of constraints obtained from combining statistically inconsistent datasets within the $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$ cosmology. In light of the CMB lensing anomalies, we show that the lensing-marginalized CMB data also favor nonzero ${f}_{\mathrm{EDE}}({z}_{c})$ at $\ensuremath{\sim}2\ensuremath{\sigma}$, predicts ${H}_{0}$ in $1.4\ensuremath{\sigma}$ agreement with sh0es and ${S}_{8}$ in $1.5\ensuremath{\sigma}$ and $0.8\ensuremath{\sigma}$ agreement with kids-viking and des respectively. There still exists however a $\ensuremath{\sim}2.5\ensuremath{\sigma}$ tension with the joint results from kids-viking and des. With an eye on Occam's razor, we finally discuss promising extensions of the EDE cosmology that could allow us to fully restore cosmological concordance.

CARPool: fast, accurate computation of large-scale structure statistics by pairing costly and cheap cosmological simulations

ABSTRACT To exploit the power of next-generation large-scale structure surveys, ensembles of numerical simulations are necessary to give accurate theoretical predictions of the statistics of observables. High-fidelity simulations come at a towering computational cost. Therefore, approximate but fast simulations, surrogates, are widely used to gain speed at the price of introducing model error. We propose a general method that exploits the correlation between simulations and surrogates to compute fast, reduced-variance statistics of large-scale structure observables without model error at the cost of only a few simulations. We call this approach Convergence Acceleration by Regression and Pooling (CARPool). In numerical experiments with intentionally minimal tuning, we apply CARPool to a handful of gadget-iii N-body simulations paired with surrogates computed using COmoving Lagrangian Acceleration. We find ∼100-fold variance reduction even in the non-linear regime, up to $k_\mathrm{max} \approx 1.2\, h {\rm Mpc^{-1}}$ for the matter power spectrum. CARPool realizes similar improvements for the matter bispectrum. In the nearly linear regime CARPool attains far larger sample variance reductions. By comparing to the 15 000 simulations from the Quijote suite, we verify that the CARPool estimates are unbiased, as guaranteed by construction, even though the surrogate misses the simulation truth by up to $60{{\ \rm per\ cent}}$ at high k. Furthermore, even with a fully configuration-space statistic like the non-linear matter density probability density function, CARPool achieves unbiased variance reduction factors of up to ∼10, without any further tuning. Conversely, CARPool can be used to remove model error from ensembles of fast surrogates by combining them with a few high-accuracy simulations.

Constraining scalar-tensor modified gravity with gravitational waves and large scale structure surveys

The first multi-messenger gravitational wave event has had a transformative effect on the space of modified gravity models. In this paper we study the enhanced tests of gravity that are possible with a future set of gravitational wave standard siren events. We perform MCMC constraint forecasts for parameters in Horndeski scalar-tensor theories. In particular, we focus on the complementarity of gravitational waves with electromagnetic large-scale structure data from galaxy surveys. We find that the addition of fifty low redshift (z ≲ 0.2) standard sirens from the advanced LIGO network offers only a modest improvement (a factor 1.1–1.3, where 1.0 is no improvement) over existing constraints from electromagnetic observations of large-scale structures. In contrast, high redshift (up to z ∼ 10) standard sirens from the future LISA satellite will improve constraints on the time evolution of the Planck mass in Horndeski theories by a factor ∼ 5. By simulating different scenarios, we find this improvement to be robust to marginalisation over unknown merger inclination angles and to variation between three plausible models for the merger source population.

Constraints on Primordial Non-Gaussianity Using the Multitracer Technique for Skew Spectra

Abstract Extracting the bispectrum information from large-scale structure observations is challenging due to the complex models and the computational costs involved in measuring the signal and its covariance. Recently, the skew spectrum was proposed to access parts of the bispectrum information in a more effective manner and was confirmed to provide complementary information to that available in power spectrum measurements. In this work, we generalize the theory to apply the multitracer technique and explore its ability to constrain the local-type primordial non-Gaussianity. Using the spectra and their covariance estimated from N-body simulations, we find that the multitracer approach is effective in reducing the cosmic variance noise. The 1σ marginalized errors for , and are reduced by 50%, 52%, and 73% compared with the results achieved using only the power spectrum obtained from a single tracer. These results indicate that both the skew spectrum and the multitracer technique are useful in constraining the primordial non-Gaussianity with the forthcoming wide-field galaxy surveys.

Study of cubic Galileon gravity using N -body simulations

We use N-body simulation to study the structure formation in the Cubic Galileon Gravity model where along with the usual kinetic and potential term we also have a higher derivative self-interaction term. We find that the large scale structure provides a unique constraining power for this model. The matter power spectrum, halo mass function, galaxy-galaxy weak lensing signal, marked density power spectrum as well as count in cell are measured. The simulations show that there are less massive halos in the Cubic Galileon Gravity model than corresponding $\Lambda$CDM model and the marked density power spectrum in these two models are different by more than $10\%$. Furthermore, the Cubic Galileon model shows significant differences in voids compared to $\Lambda$CDM. The number of low density cells is far higher in the Cubic Galileon model than that in the $\Lambda$CDM model. Therefore, it would be interesting to put constraints on this model using future large scale structure observations, especially in void regions.