Constraining Omega with Cluster Evolution

We show that the evolution of the number density of rich clusters of galaxies breaks the degeneracy between Omega (the mass density ratio of the universe) and sigma_{8} (the normalization of the power spectrum), sigma_{8}Omega^{0.5} \simeq 0.5, that follows from the observed present-day abundance of rich clusters. The evolution of high-mass (Coma-like) clusters is strong in Omega=1, low-sigma_{8} models (such as the standard biased CDM model with sigma_{8} \simeq 0.5), where the number density of clusters decreases by a factor of \sim 10^{3} from z = 0 to z \simeq 0.5; the same clusters show only mild evolution in low-Omega, high-sigma_{8} models, where the decrease is a factor of \sim 10. This diagnostic provides a most powerful constraint on Omega. Using observations of clusters to z \simeq 0.5-1, we find only mild evolution in the observed cluster abundance. We find Omega = 0.3 \pm 0.1 and sigma_{8} = 0.85 \pm 0.15 (for Lambda = 0 models; for Omega + Lambda = 1 models, Omega = 0.34 \pm 0.13). These results imply, if confirmed by future surveys, that we live in a low-den sity, low-bias universe.Comment: 14 pages, 3 Postscript figures, ApJ Letters, accepte

The Amplitude of Mass Fluctuations

We determine the linear amplitude of mass fluctuations in the universe, sigma_8, from the abundance of massive clusters at redshifts z=0.5 to 0.8. The evolution of massive clusters depends exponentially on the amplitude of mass fluctuations and thus provides a powerful measure of this important cosmological parameter. The relatively high abundance of massive clusters observed at z>0.5, and the relatively slow evolution of their abundance with time, suggest a high amplitude of mass fluctuations: sigma_8=0.9 +-10% for Omega_m=0.4, increasing slightly to sigma_8=0.95 for Omega_m=0.25 and sigma_8=1.0 for Omega_m=0.1 (flat CDM models). We use the cluster abundance observed at z=0.5 to 0.8 to derive a normalization relation from the high-redshift clusters, which is only weakly dependent on Omega_m: sigma_8*Omega_m^0.14 = 0.78 +-0.08. When combined with recent constraints from the present-day cluster mass function (sigma_8*Omega_m^0.6=0.33 +-0.03) we find sigma_8=0.98 +-0.1 and Omega_m=0.17 +-0.05. Low sigma_8 values (<0.7) are unlikely; they produce an order of magnitude fewer massive clusters than observed.Comment: 12 pages including 3 figures; updated to match published versio

Avaliação do teor de carotenoides totais em híbridos de mandioca com coloração amarela.

A importância da mandioca na alimentação do brasileiro é reconhecida desde o início da colonização do País, sendo consumida cotidianamente. Estudos comprovam que algumas variedades de mandioca apresentam em sua composição química carotenoides, que são compostos responsáveis pela coloração amarela da raiz e percussores de vitamina A, além de possuírem propriedades benéficas à saúde, tais como, aumento da resposta imune e redução do risco de doenças degenerativas como câncer

The stellar halo of isolated central galaxies in the Hyper Suprime-Cam imaging survey

We study the faint stellar halo of isolated central galaxies, by stacking galaxy images in the HSC survey and accounting for the residual sky background sampled with random points. The surface brightness profiles in HSC $r$-band are measured for a wide range of galaxy stellar masses ($9.2<\log_{10}M_\ast/M_\odot<11.4$) and out to 120 kpc. Failing to account for the stellar halo below the noise level of individual images will lead to underestimates of the total luminosity by $\leq 15\%$. Splitting galaxies according to the concentration parameter of their light distributions, we find that the surface brightness profiles of low concentration galaxies drop faster between 20 and 100 kpc than those of high concentration galaxies. Albeit the large galaxy-to-galaxy scatter, we find a strong self-similarity of the stellar halo profiles. They show unified forms once the projected distance is scaled by the halo virial radius. The colour of galaxies is redder in the centre and bluer outside, with high concentration galaxies having redder and more flattened colour profiles. There are indications of a colour minimum, beyond which the colour of the outer stellar halo turns red again. This colour minimum, however, is very sensitive to the completeness in masking satellite galaxies. We also examine the effect of the extended PSF in the measurement of the stellar halo, which is particularly important for low mass or low concentration galaxies. The PSF-corrected surface brightness profile can be measured down to $\sim$31 $\mathrm{mag}/\mathrm{arcsec}^2$ at 3-$\sigma$ significance. PSF also slightly flattens the measured colour profiles.Comment: accepted by MNRAS - Significant changes have been made compared with the first version, including discussions on the extended PSF wings, robustness of our results to source detection and masking thresholds and more detailed investigations on the indications of positive colour gradient

Avaliação de híbridos de mandioca quanto à composição das raízes.

A mandioca (Manihot esculenta Crantz) é uma planta cianogênica, pois produz glicosídeos cianogênicos, os quais podem liberar o cianeto, que é altamente tóxico. Variedades com elevados teores destes compostos nas raízes, além de riscos de envenenamento, possuem sabor desagradável; por esse motivo, são chamadas de variedades bravas ou amargas

Avaliação físico-química e microbiológica de águas minerais comercializadas em Belém-Pará.

Anualmente nota-se um aumento significativo no consumo de água mineral em todo o mundo, impulsionado pela percepção de que este consumo estaria ligado a um estilo de vida saudável, e por se acreditar que estes produtos seriam seguros. Contudo, muitas vezes estas águas contém substâncias tóxicas e microrganismos nocivos a saúde humana, estando este último ponto relacionado principalmente aos sistemas de envase e assepsia dos recipientes. Desta forma, o objetivo deste trabalho foi avaliar a qualidade físico-química (pH, nitrato, dureza e cloreto) e microbiológica (coliformes e bactérias heterotróficas) de cinco marcas de águas minerais comercializadas em Belém- Pará, sendo duas delas provenientes de envases de outros estados. De acordo com os resultados, as marcas A, B e E se mostraram impróprias para o consumo humano, o que indica a necessidade de uma maior atenção às empresas regionais de envase, uma vez que estas foram oriundas do estado do Pará

Evolution of the Cluster Mass and Correlation Functions in LCDM Cosmology

The evolution of the cluster mass function and the cluster correlation function from z = 0 to z = 3 are determined using 10^6 clusters obtained from high-resolution simulations of the current best-fit LCDM cosmology (\Omega_m = 0.27, \sigma_8 = 0.84, h = 0.7). The results provide predictions for comparisons with future observations of high redshift clusters. A comparison of the predicted mass function of low redshift clusters with observations from early Sloan Digital Sky Survey data, and the predicted abundance of massive distant clusters with observational results, favor a slightly larger amplitude of mass fluctuations (\sigma_8 = 0.9) and lower density parameter (\Omega_m = 0.2); these values are consistent within 1-\sigma with the current observational and model uncertainties. The cluster correlation function strength increases with redshift for a given mass limit; the clusters were more strongly correlated in the past, due to their increasing bias with redshift - the bias reaches b = 100 at z = 2 for M > 5 x 10^13 h^-1 M_sun. The richness-dependent cluster correlation function, represented by the correlation scale versus cluster mean separation relation, R0-d, is generally consistent with observations. This relation can be approximated as R_0 = 1.7 d^0.6 h^-1 Mpc for d = 20 - 60 h^-1 Mpc. The R0-d relation exhibits surprisingly little evolution with redshift for z < 2; this can provide a new test of the current LCDM model when compared with future observations of high redshift clusters.Comment: 20 pages, 9 figures, accepted for publication in Ap