Efeitos de torques gravitacionais na dinâmica de asteróides múltiplos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Origem dos satélites irregulares de Júpiter: captura de asteroides binários primordiais

Pós-graduação em Física - FEG

Áxions, májorons e neutrinos em extensões do modelo padrão

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Sólitons latentes, cordas negras, membranas negras e equações de estado em modelos de Kaluza-Klein

Neste trabalho investigamos soluções solitônicas em modelos de Kaluza-Klein com um número arbitrário de espaços internos toroidais, que descrevem o campo gravitacional de um objeto massivo compacto. Cada toro d_i-dimensional possui um fator de escala independente C_i, i = 1, ..., N, que é caracterizado pelo parâmetro ᵞi. Destacamos a solução fisicamente interessante correspondente à massa puntual. Para a solução geral obtemos equações de estado nos espaços externo e interno. Estas equações demonstram que a massa pontual solitônica possui equações de estado tipo poeira em todos os espaços. Obtemos também os parâmetros pósnewtonianos que nos possibilitam encontrar as fórmulas da precessão do periélio, do desvio da luz e do atraso no tempo de ecos de radar. Além disso, os experimentos gravitacionais levam a uma forte limitação nos parâmetros do modelo: T = ƩNi=1 diYi = −(2, 1±2, 3)×10⁻⁵. A solução para massa pontual com Y1 = . . . = YN = (1+ƩNi=1 di)⁻¹ contradiz esta restrição. A imposição T = 0 satisfaz essa limitação experimental e define uma nova classe de soluções que são indistinguíveis para a relatividade geral. Chamamos estas soluções de sólitons latentes. Cordas negras e membranas negras com Yi = 0 pertencem a esta classe. Além disso, a condição de estabilidade dos espaços internos destaca cordas/membranas negras de sólitons latentes, conduzindo exclusivamente para as equações de estado de corda/membrana negra p_i = −ε/2, i = 1, . . . ,N, nos espaços internos e ao número de dimensões externas d₀ = 3. As investigações do fluido perfeito multidimensional estático e esfericamente simétrico com equação de estado tipo poeira no espaço externo confirmam os resultados acima.

Petrografia, geocronologia e significado tectônico do Nefelina Sienito Brejinho: extremo noroeste da Província Borborema

No extremo noroeste da Província Borborema foi identificado um maciço alcalino subsaturado, o Nefelina Sienito Brejinho (NSB), alojado em gnaisses do Paleoproterozoico do Complexo Granja. As investigações envolveram mapeamento de detalhe do corpo, acompanhado de análises petrográficas e geocronológicas, que permitiram reconstruir a sua história evolutiva. Foram identificadas cinco fácies petrográficas, com a sua distribuição cartográfica, associações mineralógicas presentes e análises texturais/estruturais sugerindo a atuação de processos de cristalização fracionada, com forte controle da ação da gravidade e imiscibilidade de líquidos na história da cristalização magmática do maciço. Os estudos geocronológicos realizados pelo método Rb-Sr em rocha total revelaram valor de 554 ± 11 Ma, interpretado como a idade mínima para cristalização e emplacement do NSB, no final do Neoproterozoico. No contexto tectônico, esse magmatismo alcalino pode ser relacionado ao evento extensional responsável pela implantação do Gráben Jaibaras e seus correlatos no oeste do Ceará, assim como à granitogênese da região, cujas idades situam-se no intervalo entre 530 e 590 Ma. Situação semelhante é reconhecida na borda norte da Bacia do Amazonas, com o Complexo Alcalino-Ultramáfico-Carbonatítico Maicuru (589 Ma) alojado no embasamento gnáissico paleoproterozoico do Cráton Amazônico. A situação geológica e temporal do NSB permite situá-lo posteriormente à tectônica transcorrente representada na área pela Zona de Cisalhamento Santa Rosa, uma ramificação do Lineamento Transbrasiliano, e anterior à Bacia do Parnaíba. Disso resulta que esse magmatismo alcalino pode ser interpretado como um importante registro da fase rifte que prenunciou a instalação dessa bacia no início do Paleozoico. A sua caracterização, até então sem similar na Província Borborema, abre novas perspectivas de pesquisa em todo o embasamento da Bacia do Parnaíba, tendo em vista a importância tectônica e metalogenética desse tipo de magmatismo.

Determination of the top-quark pole mass and strong coupling constant from the t(t)over-bar production cross section in pp collisions at root s=7 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Measurement of the ratio of the inclusive 3-jet cross section to the inclusive 2-jet cross section in pp collisions at root s=7 TeV and first determination of the strong coupling constant in the TeV range

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Search for gravitational wave ringdowns from perturbed intermediate mass black holes in LIGO-Virgo data from 2005-2010

We report results from a search for gravitational waves produced by perturbed intermediate mass black holes ( IMBH) in data collected by LIGO and Virgo between 2005 and 2010. The search was sensitive to astrophysical sources that produced damped sinusoid gravitational wave signals, also known as ringdowns, with frequency 50 <= f(0)/Hz <= 2000 and decay timescale 0.0001 less than or similar to tau/s less than or similar to 0.1 characteristic of those produced in mergers of IMBH pairs. No significant gravitational wave candidate was detected. We report upper limits on the astrophysical coalescence rates of IMBHs with total binary mass 50 <= M/ M circle dot <= 450 and component mass ratios of either 1: 1 or 4: 1. For systems with total mass 100 <= M/M circle dot <= 150, we report a 90% confidence upper limit on the rate of binary IMBH mergers with nonspinning and equal mass components of 6.9 x 10(-8) Mpc(-3) yr(-1). We also report a rate upper limit for ringdown waveforms from perturbed IMBHs, radiating 1% of their mass as gravitational waves in the fundamental, l = m = 2, oscillation mode, that is nearly three orders of magnitude more stringent than previous results.

Measuring the Spin of Black Holes in Binary Systems Using Gravitational Waves

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Methods and results of a search for gravitational waves associated with gamma-ray bursts using the GEO 600, LIGO, and Virgo detectors

In this paper we report on a search for short-duration gravitational wave bursts in the frequency range 64 Hz-1792 Hz associated with gamma-ray bursts (GRBs), using data from GEO 600 and one of the LIGO or Virgo detectors. We introduce the method of a linear search grid to analyze GRB events with large sky localization uncertainties, for example the localizations provided by the Fermi Gamma-ray Burst Monitor (GBM). Coherent searches for gravitational waves (GWs) can be computationally intensive when the GRB sky position is not well localized, due to the corrections required for the difference in arrival time between detectors. Using a linear search grid we are able to reduce the computational cost of the analysis by a factor of O(10) for GBM events. Furthermore, we demonstrate that our analysis pipeline can improve upon the sky localization of GRBs detected by the GBM, if a high-frequency GW signal is observed in coincidence. We use the method of the linear grid in a search for GWs associated with 129 GRBs observed satellite-based gamma-ray experiments between 2006 and 2011. The GRBs in our sample had not been previously analyzed for GW counterparts. A fraction of our GRB events are analyzed using data from GEO 600 while the detector was using squeezed-light states to improve its sensitivity; this is the first search for GWs using data from a squeezed-light interferometric observatory. We find no evidence for GW signals, either with any individual GRB in this sample or with the population as a whole. For each GRB we place lower bounds on the distance to the progenitor, under an assumption of a fixed GW emission energy of 10(-2)M circle dot c(2), with a median exclusion distance of 0.8 Mpc for emission at 500 Hz and 0.3 Mpc at 1 kHz. The reduced computational cost associated with a linear search grid will enable rapid searches for GWs associated with Fermi GBM events once the advanced LIGO and Virgo detectors begin operation.

Search for Gravitational Waves Associated with gamma-ray Bursts Detected by the Interplanetary Network

We present the results of a search for gravitational waves associated with 223 gamma-ray bursts (GRBs) detected by the InterPlanetary Network (IPN) in 2005-2010 during LIGO's fifth and sixth science runs and Virgo's first, second, and third science runs. The IPN satellites provide accurate times of the bursts and sky localizations that vary significantly from degree scale to hundreds of square degrees. We search for both a well-modeled binary coalescence signal, the favored progenitor model for short GRBs, and for generic, unmodeled gravitational wave bursts. Both searches use the event time and sky localization to improve the gravitational wave search sensitivity as compared to corresponding all-time, all-sky searches. We find no evidence of a gravitational wave signal associated with any of the IPN GRBs in the sample, nor do we find evidence for a population of weak gravitational wave signals associated with the GRBs. For all IPN-detected GRBs, for which a sufficient duration of quality gravitational wave data are available, we place lower bounds on the distance to the source in accordance with an optimistic assumption of gravitational wave emission energy of 10(-2)M(circle dot)c(2) at 150 Hz, and find a median of 13 Mpc. For the 27 short-hard GRBs we place 90% confidence exclusion distances to two source models: a binary neutron star coalescence, with a median distance of 12 Mpc, or the coalescence of a neutron star and black hole, with a median distance of 22 Mpc. Finally, we combine this search with previously published results to provide a population statement for GRB searches in first-generation LIGO and Virgo gravitational wave detectors and a resulting examination of prospects for the advanced gravitational wave detectors.

Characterization of Rhinodrilus alatus hemoglobin (HbRa) and its subunits: Evidence for strong interaction with cationic surfactants DTAB and CTAC

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

NIL_004 Summary of session C6: Q&A-everything you wanted to know about gravitational waves but were afraid to ask

The paper summarizes the parallel session C6 Q&A-everything you wanted to know about gravitational waves but were afraid to ask of the joint 10th Amaldi Conference on Gravitational Waves and 20th International Conference on General Relativity and Gravitation.

Effects of litter manipulation in a tropical Eucalyptus plantation on leaching of mineral nutrients, dissolved organic nitrogen and dissolved organic carbon

Although many studies have shown that soil solution chemistry can be a reliable indicator of biogeochemical cycling in forest ecosystems, the effects of litter manipulations on the fluxes of dissolved elements in gravitational soil solutions have rarely been investigated. We estimated the fluxes of NH4-N, NO3-N, K, Ca, Mg, Na, Cl, dissolved organic nitrogen (DON) and dissolved organic carbon (DOC) over the first two years after re-planting Eucalyptus trees in the coastal area of Congo. Two treatments were replicated in two blocks after clear-cutting 7-year-old stands: in treatment R, all the litter above the mineral soil was removed before planting, and in a double slash (DS) treatment, the amount of harvest residues was doubled. The soil solutions were sampled down to a depth of 4 m and the water fluxes were estimated using the Hydrus 1D model parameterized from soil moisture measurements in 4 plots. Isotopic and spectroscopic analytical techniques were used to assess the changes in dissolved organic matter (DOM) properties throughout the transfer in the soil. The first year after planting, the fluxes of NH4-N, K, Ca, Mg, Na, Cl and DOC in the topsoil of the DS treatment were 2-5 times higher than in R, which showed that litter was a major source of dissolved nutrients. Nutrient fluxes in gravitational solutions decreased sharply in the second year after planting, irrespective of the soil depth, as a result of intense nutrient uptake by Eucalyptus trees. Losses of dissolved nutrients were noticeably low in these Eucalyptus plantations despite a low cation exchange capacity, a coarse soil texture and large amounts of harvest residues left on-site at the clear cut in the DS treatment. All together, these results clarified the strong effect of litter manipulation observed on eucalypt growth in Congolese sandy soils. DOM fluxes, as well as changes in delta C-13, C:N and aromaticity of DOM throughout the soil profile showed that the organic compounds produced in the litter layer were mainly consumed by microorganisms or retained in the topsoil. Below a depth of 15 cm, most of the DOC and the DON originated from the first 2 cm of the soil and the exchanges between soil solutions and soil organic matter were low. (C) 2014 Elsevier B.V. All rights reserved.