29 research outputs found

    Using cosmic voids to distinguish f(R) gravity in future galaxy surveys

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    We use properties of void populations identified in N-body simulations to forecast the ability of upcoming galaxy surveys to differentiate models of f (R) gravity from cold dark matter cosmology. We analyse multiple simulation realizations, which were designed to mimic the expected number densities, volumes, and redshifts of the upcoming Euclid satellite and a lower-redshift ground-based counterpart survey, using the public VIDE toolkit. We examine void abundances, ellipicities, radial density profiles, and radial velocity profiles at redshifts 1.0 and 0.43. We find that stronger f (R) coupling strengths eliminates small voids and produces voids up to ∼20 per cent larger in radius, leading to a significant tilt in the void number function. Additionally, under the influence of modified gravity, voids at all scales tend to be measurably emptier with correspondingly higher compensation walls. The velocity profiles reflect this, showing increased outflows inside voids and increased inflows outside voids. Using the void number function as an example, we forecast that future surveys can constrain the modified gravity coupling strength to ∼3 × 10−5 using voids

    Multipole analysis of redshift-space distortions around cosmic voids

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    We perform a comprehensive redshift-space distortion analysis based on cosmic voids in the large-scale distribution of galaxies observed with the Sloan Digital Sky Survey. To this end, we measure multipoles of the void-galaxy cross-correlation function and compare them with standard model predictions in cosmology. Merely considering linear-order theory allows us to accurately describe the data on the entire available range of scales and to probe void-centric distances down to about 2h1Mpc2h^{-1}{\rm Mpc}. Common systematics, such as the Fingers-of-God effect, scale-dependent galaxy bias, and nonlinear clustering do not seem to play a significant role in our analysis. We constrain the growth rate of structure via the redshift-space distortion parameter β\beta at two median redshifts, β(zˉ=0.32)=0.5990.124+0.134\beta(\bar{z}=0.32)=0.599^{+0.134}_{-0.124} and β(zˉ=0.54)=0.4570.054+0.056\beta(\bar{z}=0.54)=0.457^{+0.056}_{-0.054}, with a precision that is competitive with state-of-the-art galaxy-clustering results. While the high-redshift constraint perfectly agrees with model expectations, we observe a mild 2σ2\sigma deviation at zˉ=0.32\bar{z}=0.32, which increases to 3σ3\sigma when the data is restricted to the lowest available redshift range of 0.15<z<0.330.15<z<0.33.Comment: 20 pages, 11 figures. Minor fixes, conclusions unchanged. Reflects published versio

    ENRAIZAMENTO DE CRAVO (Dianthus caryophyllus L.) IN VITRO E EX VITRO

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    Plântulas de cravo (Dianthus caryophyllus) micropropagadas durante várias gerações pelo período de um ano, foram enraizadas in vitro com AIA, ANA e AIB nas concentrações de 0,0; 0,25; 0,5 e 1,0 mg/l, em fatorial do tipo 3 x 4, com todos os tratamentos promovendo a formação de raízes, mas não diferindo do controle. Foi confrontado em condição autotrófica, o desempenho entre plântulas enraizadas in vitro na presença e ausência do regulador AIA 0,5 mg/l e plântulas enraizadas ex vitro, sem nenhuma diferença quanto ao comprimento da parte aérea. Para a variável produção de massa de matéria seca os melhores resultados foram proporcionados pelas plantas que passaram pela fase de enraizamento in vitro, tendo o sistema radicular efeito sinergístico no crescimento da parte aérea.<br>Plantlets of carnation (Dianthus caryophyllus L.) micropropagated through several generations during one year, were observed with respect to rooting in vitro, in the presence of IAA , NAA and IBA, at the following concentrations: 0,0; 0,25; 0,5 and 1,0 mg/l. All treatments promoted root formation, however no differences were detected in comparison to control. As far as the lenght of the aerial part is concerned no difference was observed between in vitro rooting. in the presence or absence of IAA 0,5 mg/l, and ex vitro rooting. Plantlets which were rooted in vitro conditions showed higher production of fresh matter then those rooted ex vitro. The root system had a synergistic effect on the growth of the aerial part
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