1,995 research outputs found

    Cycle expansions with pruned orbits have branch points

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    Cycle expansions are an efficient scheme for computing the properties of chaotic systems. When enumerating the orbits for a cycle expansion not all orbits that one would expect at first are present --- some are pruned. This pruning leads to convergence difficulties when computing properties of chaotic systems. In numerical schemes, I show that pruning reduces the number of reliable eigenvalues when diagonalizing quantum mechanical operators, and that pruning slows down the convergence rate of cycle expansion calculations. I then exactly solve a diffusion model that displays chaos and show that its cycle expansion develops a branch point.Comment: 17 pages and 9 figures in 183364 bytes of uuencoded compressed PostScrip

    Black hole accretion and host galaxies of obscured quasars in XMM-COSMOS

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    Aims. We explore the connection between black hole growth at the center of obscured quasars selected from the XMM-COSMOS survey and the physical properties of their host galaxies. We study a bolometric regime ( ⟨ L_(bol) ⟩ = 8 × 10^(45) erg s^(-1)) where several theoretical models invoke major galaxy mergers as the main fueling channel for black hole accretion. Methods. To derive robust estimates of the host galaxy properties, we use an SED fitting technique to distinguish the AGN and host galaxy emission. We evaluate the effect on galaxy properties estimates of being unable to remove the nuclear emission from the SED. The superb multi-wavelength coverage of the COSMOS field allows us to obtain reliable estimates of the total stellar masses and star formation rates (SFRs) of the hosts. We supplement this information with a morphological analysis of the ACS/HST images, optical spectroscopy, and an X-ray spectral analysis. Results. We confirm that obscured quasars mainly reside in massive galaxies (M_⋆ > 10^(10)M_⊙) and that the fraction of galaxies hosting such powerful quasars monotonically increases with the stellar mass. We stress the limitation of the use of rest-frame color − magnitude diagrams as a diagnostic tool for studying galaxy evolution and inferring the influence that AGN activity can have on such a process. We instead use the correlation between SFR and stellar mass found for star-forming galaxies to discuss the physical properties of the hosts. We find that at z ~ 1, ≈62% of Type-2 QSOs hosts are actively forming stars and that their rates are comparable to those measured for normal star-forming galaxies. The fraction of star-forming hosts increases with redshift: ≈ 71% at z ~ 2, and 100% at z ~ 3. We also find that the evolution from z ~ 1 to z ~ 3 of the specific SFR of the Type-2 QSO hosts is in excellent agreement with that measured for star-forming galaxies. From the morphological analysis, we conclude that most of the objects are bulge-dominated galaxies, and that only a few of them exhibit signs of recent mergers or disks. Finally, bulge-dominated galaxies tend to host Type-2 QSOs with low Eddington ratios (λ 0.1)

    Two-Face(s): ionized and neutral gas winds in the local Universe

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    We present a comprehensive study of the Na I λ\lambda5890, 5895 (Na I D) resonant lines in the Sloan Digital Sky Survey (SDSS, DR7) spectroscopic sample to look for neutral gas outflows in the local galaxies. Individual galaxy spectra are stacked in bins of M{\star} and SFR to investigate the dependence of galactic wind occurrence and velocity as a function of the galaxy position in the SFR-MM{\star} plane. In massive galaxies at the high SFR tail we find evidence of a significant blue-shifted Na I D absorption, which we interpret as evidence of neutral outflowing gas. The occurrence of the blue-shifted absorption is observed at the same significance for purely SF galaxies, AGN and composite systems at fixed SFR. In all classes of objects the blue-shift is the largest and the Na I D equivalent width the smallest for face-on galaxies while the absorption feature is at the systemic velocity for edge-on systems. This indicates that the neutral outflow is mostly perpendicular or biconical with respect to the galactic disk. We also compare the kinematics of the neutral gas with the ionized gas phase as traced by the [OIII]λ\lambda5007, Hα\alpha, [NII]λ6548\lambda6548 and [NII]λ6584\lambda6584 emission lines. Differently for the neutral gas phase, all the emission lines show evidence of perturbed kinematics only in galaxies with a significant level of nuclear activity and, they are independent from the disk inclination. In conclusion, we find that, in the local Universe, galactic winds show two faces which are related to two different ejection mechanisms, namely the neutral outflowing gas phase related to the SF activity along the galaxy disk and the ionized phase related to the AGN feedback. In both the neutral and ionized gas phases, the observed wind velocities suggest that the outflowing gas remains bound to the galaxy with no definitive effect on the gas reservoir.Comment: Accepted to A&A, 13 pages, 9 figure

    A Desinstitucionalização como Transvaloração. Apontamentos para uma terapêutica ao niilismo

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    Diante das dificuldades de construção de alternativas de cuidado em Saúde Mental que esbarram em lógicas características do paradigma biologicista, ainda tão arraigado às ciências humanas, faz-se necessária uma discussão acerca dos processos subjetivos que possam estar concorrendo para a manutenção de práticas tão institucionalizadas quanto criticadas na atualidade. O presente artigo debruça-se sobre esse impasse, propondo, como um possível passo no sentido de superá-lo, a análise da relação existente entre os conceitos de subjetividade, niilismo e instituição. Como ferramentas teóricas, utiliza a desconstrução da metafísica ocidental e as contribuições de Foucault e Deleuze relativas à constituição da singularidade para aproximar a compreensão do processo de desinstitucionalização ao projeto nietzscheano de transvaloração dos valores constituintes de nossa cultura.Establishing alternative mental health care has been facing several difficulties. We need to examine the subjective processes that may be supporting archaic and criticized practices in this area. The aim of this article is to analyze the relationship between the concepts of subjectivity, nihilism and institutionality in order to overcome the impasse in which deinstitutionalization finds itself. Taking Foucault and Deleuze as theoretical tools to understand the constitution of singularity, this paper focuses on the deinstitutionalization process in order to bring it closer to the Nietzschean project of transvaluation of values
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