Large-scale Mass Distribution Research Articles

Generation of realistic input parameters for simulating atmospheric point-spread functions at astronomical observatories

High-fidelity simulated astronomical images are an important tool in developing and measuring the performance of image-processing algorithms, particularly for high precision measurements of cosmic shear – correlated distortions of images of distant galaxies due to weak gravitational lensing caused by the large-scale mass distribution in the Universe. For unbiased measurements of cosmic shear, all other sources of correlated image distortions must be modeled or removed. One such source is the correlated blurring of images due to optical turbulence in the atmosphere, which dominates the point-spread function (PSF) for ground-based instruments. In this work, we leverage data from weather forecasting models to produce wind speeds and directions, and turbulence parameters, that are realistically correlated with altitude. To study the resulting correlations in the size and shape of the PSF, we generate simulated images of the PSF across a ~10 square-degree field of view – the size of the camera focal plane for the Vera C. Rubin Observatory in Chile – using weather data and historical seeing for a geographic location near the Observatory. We make quantitative predictions for two-point correlation functions (2PCF) that are used in analyses of cosmic shear. We observe a strong anisotropy in the two-dimensional 2PCF, which is expected based on observations in real images, and study the dependence of the orientation of the anisotropy on dominant wind directions near the ground and at higher altitudes. The code repository for producing the correlated weather parameters for input to simulations (psf-weather-station) is public at https://github.com/LSSTDESC/psf-weather-station (https://github.com/LSSTDESC/psf-weather-station)

A CMB lensing analysis of the extended mass distribution of clusters

ABSTRACT The aim of this work is to study the anisotropic weak lensing signal associated with the mass distribution of massive clusters of galaxies using the cosmic microwave background (CMB) data. For this purpose, we stack patches of the Planck Collaboration (2018) CMB lensing convergence map centred on SDSS DR8 redMaPPer clusters within the redshift range [0.4, 0.5]. We obtain mean radial profiles of the convergence parameter κ finding strong signals at scales as large as 40 Mpch−1. By orienting the clusters along their major axis defined through the galaxy member distribution, we find a significant difference between the parallel and perpendicular-oriented convergence profiles. The amplitude of the profile along the parallel direction is about 50 per cent larger than that along the perpendicular direction, indicating that the clusters are well aligned with the surrounding mass distribution. From a model with an anisotropic surface mass density, we obtain a suitable agreement for both mass and ellipticities of clusters compared to results derived from weak lensing shear estimates, finding strong evidence of the correlation between the galaxy cluster member distribution and the large-scale mass distribution.

The information content of projected galaxy fields

ABSTRACT The power spectrum of the non-linearly evolved large-scale mass distribution recovers only a minority of the information available on the mass fluctuation amplitude. We investigate the recovery of this information in 2D ‘slabs’ of the mass distribution averaged over ≈100 h−1 Mpc along the line of sight, as might be obtained from photometric redshift surveys. We demonstrate a Hamiltonian Monte Carlo method to reconstruct the non-Gaussian mass distribution in slabs, under the assumption that the projected field is a point-transformed Gaussian random field, Poisson-sampled by galaxies. When applied to the Quijote N-body suite at z = 0.5 and at a transverse resolution of 2 h−1 Mpc, the method recovers ∼30 times more information than the 2D power spectrum in the well-sampled limit, recovering the Gaussian limit on information. At a more realistic galaxy sampling density of 0.01 h3 Mpc−3, shot noise reduces the information gain to a factor of 5 improvement over the power spectrum at resolutions of 4 h−1 Mpc or smaller.

AMICO galaxy clusters in KiDS-DR3

Context. The large-scale mass distribution around dark matter haloes hosting galaxy clusters provides sensitive cosmological information. Aims. In this work we make use of a large photometric galaxy cluster sample, constructed from the public Third Data Release of the Kilo-Degree Survey, and the corresponding shear signal, to assess cluster masses and test the concordance Λ-cold dark matter (ΛCDM) model. In particular, we study the weak gravitational lensing effects on scales beyond the cluster virial radius, where the signal is dominated by correlated and uncorrelated matter density distributions along the line of sight. The analysed catalogue consists of 6962 galaxy clusters, in the redshift range 0.1 ≤ z ≤ 0.6 and with signal-to-noise ratios higher than 3.5. Methods. We perform a full Bayesian analysis to model the stacked shear profiles of these clusters. The adopted likelihood function considers both the small-scale one-halo term, used primarily to constrain the cluster structural properties, and the two-halo term, that can be used to constrain cosmological parameters. Results. We find that the adopted modelling is successful in assessing both the cluster masses and the total matter density parameter, ΩM, when fitting shear profiles up to the largest available scales of 35 Mpc h−1. Moreover, our results provide a strong observational evidence of the two-halo signal in the stacked gravitational lensing of galaxy clusters, further demonstrating the reliability of this probe for cosmological studies. The main result of this work is a robust constraint on ΩM, assuming a flat ΛCDM cosmology. We get ΩM = 0.29 ± 0.02, estimated from the full posterior probability distribution, consistent with the estimates from cosmic microwave background experiments.

Scaling Laws in the Stellar Mass Distribution and the Transition to Homogeneity

We present a new statistical analysis of the large-scale stellar mass distribution in the Sloan Digital Sky Survey (data release 7). A set of volume-limited samples shows that the stellar mass of galaxies is concentrated in a range of galaxy luminosities that is very different from the range selected by the usual analysis of galaxy positions. Nevertheless, the two-point correlation function is a power-law with the usual exponent γ = 1.71 − 1.82 , which varies with luminosity. The mass concentration property allows us to make a meaningful analysis of the angular distribution of the full flux-limited sample. With this analysis, after suppressing the shot noise, we extend further the scaling range and thus obtain γ = 1.83 and a clustering length r 0 = 5.8 − 7.0 h − 1 Mpc . Fractional statistical moments of the coarse-grained stellar mass density exhibit multifractal scaling. Our results support a multifractal model with a transition to homogeneity at about 10 h − 1 Mpc .

Costs of insecticide-treated bed net distribution systems in sub-Saharan Africa

BackgroundInsecticide-treated nets (ITNs) are one of the most cost-effective measures for preventing malaria. The World Health Organization recommends both large-scale mass distribution campaigns and continuous distributions (CD) as part of a multifaceted strategy to achieve and sustain universal access to ITNs. A combination of these strategies has been effective for scaling up ITN access. For policy makers to make informed decisions on how to efficiently implement CD or combined strategies, information on the costs and cost-effectiveness of these delivery systems is necessary, but relatively few published studies of the cost continuous distribution systems exist.MethodsTo address the gap in continuous distribution cost data, four types of delivery systems—CD through antenatal care services (ANC) and the expanded programme on immunization (EPI) (Ghana, Mali, and mainland Tanzania), CD through schools (Ghana and mainland Tanzania), and a combined community/health facility-based distribution (Zanzibar, Tanzania), as well as mass distributions (Mali)—were costed. Data on costs were collected retrospectively from financial and operational records, stakeholder interviews, and resource use surveys.ResultsOverall, from a full provider perspective, mass distributions and continuous systems delivered ITNs at overlapping economic costs per net distributed (mass distributions: 4.37–4.61 USD, CD channels: 3.56–9.90 USD), with two of the school-based systems and the mass distributions at the lower end of this range. From the perspective of international donors, the costs of the CD systems were, for the most part, less costly than the mass distributions (mass distributions: 4.34–4.55 USD, Ghana and Tanzania 2017 school-based: 3.30–3.69 USD, health facility-based: 3.90–4.55 USD, combined community/health facility 4.55 USD). The 2015 school-based distribution (7.30 USD) and 2016 health facility-based distribution (6.52 USD) programmes in Tanzania were an exception. Mass distributions were more heavily financed by donors, while CD relied more extensively on domestic resource contributions.ConclusionsThese results suggest that CD strategies can continue to deliver nets at a comparable cost to mass distributions, especially from the perspective of the donor.

Neo-Industrial Future of Ukraine: Expectations vs Obstacles

The significant features of the process of neo-industrialization are studied in conjunction with the profound changes in the post-industrial society, which determine the specifics of this stage of industrial development. however, are currently absent in Ukraine. Neo-industrialization, as a component of the knowledge economy, is not limited only to the processes of post-industrial technological transformations by changing the sectoral structure of the eco- nomy and industrial restructuring. The analysis of factors that led to the emergence of completely new processes of organizational change in the post-industrial society, in which large-scale mass production and mass distribution of goods are no longer progressive methods, as a result, eco- nomies of scale are no longer a market advantage in a neoindustrial economy. At a higher stage of development, differentiated goods and services are becoming increasingly demanded. And this diversity of offers is harmonized by the diversity of demand and is a constant engine of the innovation process in developed economies, and highly-differentiated structure of industrial production is a factor and the result of this diversity. The problems of small business development, which is becoming an important component of the neo-industrial structure, without its effective functioning in the conditions of market segmentation and demand fragmentation are considered, are examined. Statistical data and indices that measure the level of technolo- gical readiness of the country’s economy (global competitiveness index, economic complexity index, etc.) are analyzed in detail. Based on the analysis, systemic problems are identified and the conclusion is made that the existing structure of the Ukrainian economy in any aspect (industry, resource, foreign trade) does not meet the modern requirements of the country’s neo-industrial development.

Fractal analysis of the large-scale stellar mass distribution in the Sloan Digital Sky Survey

A novel fractal analysis of the cosmic web structure is carried out, employing the Sloan Digital Sky Survey, data release 7. We consider the large-scale stellar mass distribution, unlike other analyses, and determine its multifractal geometry, which is compared with the geometry of the cosmic web generated by cosmological N-body simulations. We find a good concordance, the common features being: (i) a minimum singularity strength αmin = 1, which corresponds to the edge of diverging gravitational energy and differs from the adhesion model prediction; (ii) a “supercluster set” of relatively high dimension where the mass concentrates; and (iii) a non-lacunar structure, like the one generated by the adhesion model.

The shape of galaxy dark matter haloes in massive galaxy clusters: insights from strong gravitational lensing

We assess how much unused strong lensing information is available in the deep \emph{Hubble Space Telescope} imaging and VLT/MUSE spectroscopy of the \emph{Frontier Field} clusters. As a pilot study, we analyse galaxy cluster MACS\,J0416.1-2403 ($z$$=$$0.397$, $M(R<200\,{\rm kpc})$$=$$1.6$$\times$$10^{14}\msun$), which has 141 multiple images with spectroscopic redshifts. We find that many additional parameters in a cluster mass model can be constrained, and that adding even small amounts of extra freedom to a model can dramatically improve its figures of merit. We use this information to constrain the distribution of dark matter around cluster member galaxies, simultaneously with the cluster's large-scale mass distribution. We find tentative evidence that some galaxies' dark matter has surprisingly similar ellipticity to their stars (unlike in the field, where it is more spherical), but that its orientation is often misaligned. When non-coincident dark matter and baryonic halos are allowed, the model improves by 35\%. This technique may provide a new way to investigate the processes and timescales on which dark matter is stripped from galaxies as they fall into a massive cluster. Our preliminary conclusions will be made more robust by analysing the remaining five \emph{Frontier Field} clusters.

Exploring cosmic origins with CORE: Gravitational lensing of the CMB

Lensing of the cosmic microwave background (CMB) is now a well-developed probe of the clustering of the large-scale mass distribution over a broad range of redshifts. By exploiting the non-Gaussian imprints of lensing in the polarization of the CMB, the CORE mission will allow production of a clean map of the lensing deflections over nearly the full-sky. The number of high-S/N modes in this map will exceed current CMB lensing maps by a factor of 40, and the measurement will be sample-variance limited on all scales where linear theory is valid. Here, we summarise this mission product and discuss the science that will follow from its power spectrum and the cross-correlation with other clustering data. For example, the summed mass of neutrinos will be determined to an accuracy of 17 meV combining CORE lensing and CMB two-point information with contemporaneous measurements of the baryon acoustic oscillation feature in the clustering of galaxies, three times smaller than the minimum total mass allowed by neutrino oscillation measurements. Lensing has applications across many other science goals of CORE, including the search for B-mode polarization from primordial gravitational waves. Here, lens-induced B-modes will dominate over instrument noise, limiting constraints on the power spectrum amplitude of primordial gravitational waves. With lensing reconstructed by CORE, one can “delens” the observed polarization internally, reducing the lensing B-mode power by 60 %. This can be improved to 70 % by combining lensing and measurements of the cosmic infrared background from CORE, leading to an improvement of a factor of 2.5 in the error on the amplitude of primordial gravitational waves compared to no delensing (in the null hypothesis of no primordial B-modes). Lensing measurements from CORE will allow calibration of the halo masses of the tens of thousands of galaxy clusters that it will find, with constraints dominated by the clean polarization-based estimators. The 19 frequency channels proposed for CORE will allow accurate removal of Galactic emission from CMB maps. We present initial findings that show that residual Galactic foreground contamination will not be a significant source of bias for lensing power spectrum measurements with CORE.

Developing a comprehensive response for treatment of children under 6\xa0years of age with schistosomiasis: research and development of a pediatric formulation of praziquantel

Schistosomiasis is a parasitic disease caused by blood flukes. The disease is caused by an inflammatory reaction to parasite eggs retained in the liver, bladder and reproductive organs. According to 2017 World Health Organization (WHO) estimates 220 million people are potentially infected, from which probably 10% are children under 6 years of age. The regular treatment approach of a single, oral dose of 40 mg/kg body weight with praziquantel however, is difficult for children under the age of 6, leaving them without a treatment option.In order to address this important gap in treatment target populations, an international public-private partnership that works on a not-for-profit basis in the field of drug research and development for schistosomiasis was established in 2012. This is called the Pediatric Praziquantel Consortium. Its mission was and continues to be to develop, register and provide access to a suitable pediatric praziquantel formulation for treating schistosomiasis in preschool-age children (3–6 months up to 6 years).The Target Product Profile for the pediatric formulation of praziquantel that would be suitable to treat children as young as 3–6 months was then defined by a group of experts, including members from the Pediatric Praziquantel Consortium partner organizations as well as experts from WHO (as observer) and schistosomiasis endemic countries.The development of the drug is ongoing and the Pediatric Praziquantel Consortium aims to submit the regulatory dossier for marketing approval in endemic countries and WHO prequalification in 2018/19 with approval and product launch for schistosomiasis pediatric case management in key endemic countries in 2019. Ultimately, the goal is for the product to be considered for a large-scale mass distribution program by 2022.

The association between household bed net ownership and all-cause child mortality in Madagascar.

BackgroundMalaria continues to be an important cause of morbidity and mortality in Madagascar. It has been estimated that the malaria burden costs Madagascar over $52 million annually in terms of treatment costs, lost productivity and prevention expenses. One of the key malaria prevention strategies of the Government of Madagascar consists of large-scale mass distribution campaigns of long-lasting insecticide-treated bed nets (LLIN). Although there is ample evidence that child mortality has decreased in Madagascar, it is unclear whether increases in LLIN ownership have contributed to this decline. This study analyses multiple recent cross-sectional survey data sets to examine the association between household bed net ownership and all-cause child mortality.ResultsData on household-level bed net ownership confirm that the percentage of households that own one or more bed nets increased substantially following the 2009 and 2010 mass LLIN distribution campaigns. Additionally, all-cause child mortality in Madagascar has declined during the period 2008–2013. Bed net ownership was associated with a 22 % reduction in the all-cause child mortality hazard in Madagascar.ConclusionsMass bed net distributions contributed strongly to the overall decline in child mortality in Madagascar during the period 2008–2013. However, the decline was not solely attributable to increases in bed net coverage, and nets alone were not able to eliminate most of the child mortality hazard across the island.

Large-scale mass distribution in the Illustris simulation

Observations at low redshifts thus far fail to account for all of the baryons expected in the Universe according to cosmological constraints. A large fraction of the baryons presumably resides in a thin and warm-hot medium between the galaxies, where they are difficult to observe due to their low densities and high temperatures. Cosmological simulations of structure formation can be used to verify this picture and provide quantitative predictions for the distribution of mass in different large-scale structure components. Here we study the distribution of baryons and dark matter at different epochs using data from the Illustris simulation. We identify regions of different dark matter density with the primary constituents of large-scale structure, allowing us to measure mass and volume of haloes, filaments and voids. At redshift zero, we find that 49 % of the dark matter and 23 % of the baryons are within haloes more massive than the resolution limit of $2\times 10^8$ M$_\odot$. The filaments of the cosmic web host a further 45 % of the dark matter and 46 % of the baryons. The remaining 31 % of the baryons reside in voids. The majority of these baryons have been transported there through active galactic nuclei feedback. We note that the feedback model of Illustris is too strong for heavy haloes, therefore it is likely that we are overestimating this amount. Categorizing the baryons according to their density and temperature, we find that 17.8 % of them are in a condensed state, 21.6 % are present as cold, diffuse gas, and 53.9 % are found in the state of a warm-hot intergalactic medium.

Statistics of Caustics in Large-Scale Structure Formation

AbstractThe cosmic web is a complex spatial pattern of walls, filaments, cluster nodes and underdense void regions. It emerged through gravitational amplification from the Gaussian primordial density field. Here we infer analytical expressions for the spatial statistics of caustics in the evolving large-scale mass distribution. In our analysis, following the quasi-linear Zel'dovich formalism and confined to the 1D and 2D situation, we compute number density and correlation properties of caustics in cosmic density fields that evolve from Gaussian primordial conditions. The analysis can be straightforwardly extended to the 3D situation. We moreover, are currently extending the approach to the non-linear regime of structure formation by including higher order Lagrangian approximations and Lagrangian effective field theory.

Large-Scale Ichthyoplankton and Water Mass Distribution along the South Brazil Shelf

Ichthyoplankton is an essential component of pelagic ecosystems, and environmental factors play an important role in determining its distribution. We have investigated simultaneous latitudinal and cross-shelf gradients in ichthyoplankton abundance to test the hypothesis that the large-scale distribution of fish larvae in the South Brazil Shelf is associated with water mass composition. Vertical plankton tows were collected between 21°27′ and 34°51′S at 107 stations, in austral late spring and early summer seasons. Samples were taken with a conical-cylindrical plankton net from the depth of chlorophyll maxima to the surface in deep stations, or from 10 m from the bottom to the surface in shallow waters. Salinity and temperature were obtained with a CTD/rosette system, which provided seawater for chlorophyll-a and nutrient concentrations. The influence of water mass on larval fish species was studied using Indicator Species Analysis, whereas environmental effects on the distribution of larval fish species were analyzed by Distance-based Redundancy Analysis. Larval fish species were associated with specific water masses: in the north, Sardinella brasiliensis was found in Shelf Water; whereas in the south, Engraulis anchoita inhabited the Plata Plume Water. At the slope, Tropical Water was characterized by the bristlemouth Cyclothone acclinidens. The concurrent analysis showed the importance of both cross-shelf and latitudinal gradients on the large-scale distribution of larval fish species. Our findings reveal that ichthyoplankton composition and large-scale spatial distribution are determined by water mass composition in both latitudinal and cross-shelf gradients.

Primordial Non-Gaussianity in the Large-Scale Structure of the Universe

Primordial non-Gaussianity is a potentially powerful discriminant of the physical mechanisms that generated the cosmological fluctuations observed today. Any detection of significant non-Gaussianity would thus have profound implications for our understanding of cosmic structure formation. The large-scale mass distribution in the Universe is a sensitive probe of the nature of initial conditions. Recent theoretical progress together with rapid developments in observational techniques will enable us to critically confront predictions of inflationary scenarios and set constraints as competitive as those from the Cosmic Microwave Background. In this paper, we review past and current efforts in the search for primordial non-Gaussianity in the large-scale structure of the Universe.

Increasing Coverage and Decreasing Inequity in Insecticide-Treated Bed Net Use among Rural Kenyan Children

BackgroundInexpensive and efficacious interventions that avert childhood deaths in sub-Saharan Africa have failed to reach effective coverage, especially among the poorest rural sectors. One particular example is insecticide-treated bed nets (ITNs). In this study, we present repeat observations of ITN coverage among rural Kenyan homesteads exposed at different times to a range of delivery models, and assess changes in coverage across socioeconomic groups.Methods and FindingsWe undertook a study of annual changes in ITN coverage among a cohort of 3,700 children aged 0–4 y in four districts of Kenya (Bondo, Greater Kisii, Kwale, and Makueni) annually between 2004 and 2006. Cross-sectional surveys of ITN coverage were undertaken coincidentally with the incremental availability of commercial sector nets (2004), the introduction of heavily subsidized nets through clinics (2005), and the introduction of free mass distributed ITNs (2006). The changing prevalence of ITN coverage was examined with special reference to the degree of equity in each delivery approach. ITN coverage was only 7.1% in 2004 when the predominant source of nets was the commercial retail sector. By the end of 2005, following the expansion of heavily subsidized clinic distribution system, ITN coverage rose to 23.5%. In 2006 a large-scale mass distribution of ITNs was mounted providing nets free of charge to children, resulting in a dramatic increase in ITN coverage to 67.3%. With each subsequent survey socioeconomic inequity in net coverage sequentially decreased: 2004 (most poor [2.9%] versus least poor [15.6%]; concentration index 0.281); 2005 (most poor [17.5%] versus least poor [37.9%]; concentration index 0.131), and 2006 with near-perfect equality (most poor [66.3%] versus least poor [66.6%]; concentration index 0.000). The free mass distribution method achieved highest coverage among the poorest children, the highly subsidised clinic nets programme was marginally in favour of the least poor, and the commercial social marketing favoured the least poor.ConclusionsRapid scaling up of ITN coverage among Africa's poorest rural children can be achieved through mass distribution campaigns. These efforts must form an important adjunct to regular, routine access to ITNs through clinics, and each complimentary approach should aim to make this intervention free to clients to ensure equitable access among those least able to afford even the cost of a heavily subsidized net.

Technological innovation and the rise of the department store in the 19th century

Technology, as an agent of growth and prosperity, is most commonly associated with the production side of the economy. However, other sectors, notably retailing (i.e., part of the distribution side of the economy), have also contributed significantly to advances in technology, economic growth and the betterment of society. From an historical perspective, technology and retailing have been inextricably linked both in terms of their development and their ability to deliver unique benefits to consumers. The focus of this paper is to demonstrate how the department store, as a large-scale mass distribution institution of the 19th century, has contributed directly or indirectly to the spread of certain technological innovations and, similarly, the extent to which technological innovation in turn aided in the rise of the phenomenon of the 19th century department store.

First Cosmic Shear Results from the Canada‐France‐Hawaii Telescope Wide Synoptic Legacy Survey

We present the first measurements of the weak gravitational lensing signal induced by the large scale mass distribution from data obtained as part of the ongoing Canada-France-Hawaii Telescope Legacy Survey (CFHTLS). The data used in this analysis are from the Wide Synoptic Survey, which aims to image ~170 square degree in five filters. We have analysed ~22 deg2 (31 pointings) of i' data spread over two of the three survey fields. These data are of excellent quality and the results bode well for the remainder of the survey: we do not detect a significant `B'-mode, suggesting that residual systematics are negligible at the current level of accuracy. Assuming a Cold Dark Matter model and marginalising over the Hubble parameter h=[0.6,0.8], the source redshift distribution and systematics, we constrain sigma_8, the amplitude of the matter power spectrum. At a fiducial matter density Omega_m=0.3 we find sigma_8=0.85+-0.06. This estimate is in excellent agreement with previous studies. Combination of our results with those from the Deep component of the CFHTLS enables us to place a constraint on a constant equation of state for the dark energy, based on cosmic shear data alone. We find that w_0<-0.8 at 68% confidence.

The cosmological principle and honeycombs

We present the possibility that the gravitational growth of primordial density fluctuations leads to what can be considered a weak version of the cosmological principle. The large-scale mass distribution associated with this principle must have the geometrical structure known as a regular honeycomb. We give the most important parameters that characterize the honeycombs associated with the closed, open, and flat Friedmann–Lemaître–Robertson–Walker models. These parameters can be used to determine by means of observations which is the appropriate honeycomb. For each of these honeycombs, and for a nearly flat universe, we have calculated the probability that a randomly placed observer could detect the honeycomb as a function of the density parameters Ω0 and ΩΛ0.