23 research outputs found

    On the evolution of environmental and mass properties of strong lens galaxies in COSMOS

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    Among the 100 strong lens candidates found in the COSMOS field, 20 with redshifts in the range [0.34,1.13], feature multiple images of background sources. Using the multi-wavelength coverage of the field and its spectroscopic follow-up, we characterize the evolution with redshift of the environment and of the dark-matter (DM) fraction of the lens galaxies. We present new redshift of the strong lens candidates. The lens environment is characterized by the projected 10 closest galaxies around each lens and by the number of galaxies with a projected distance less than 1Mpc at the lens galaxy redshift. In both cases, we perform similar measurements on a control sample of twin non-lens early type galaxies (ETGs). In addition, we identify group members and field galaxies in the X-ray and optical catalogs of galaxy groups. From those catalogs, we measure the external shear contribution at the lens galaxy positions. The systems are then modeled using a SIE plus the external shear due to the groups. We observe that the average stellar mass of lens galaxies increases with z and that the environment of lens galaxies is compatible with that of the twins. During the lens modeling, we notice that, when let free, the external shear points in a direction which is the mean direction of the external shear due to groups and of the closest galaxy to the lens. We notice that the DM fraction of the lens galaxies within the Einstein radius decreases as the redshift increases. Given these, we conclude that, while the environment of lens galaxies is compatible with that of non-lens ETGS, their mass properties evolves significantly with redshift: it is still not clear whether this advocates in favor of a stronger lensing bias toward massive objects at high redshift or is simply representative of the high proportion of massive and high stellar density galaxies at high redshift.Comment: Accepted for publication in A&A. Significant modifications in the paper but similar conclusion

    The Hubble Constant

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    I review the current state of determinations of the Hubble constant, which gives the length scale of the Universe by relating the expansion velocity of objects to their distance. There are two broad categories of measurements. The first uses individual astrophysical objects which have some property that allows their intrinsic luminosity or size to be determined, or allows the determination of their distance by geometric means. The second category comprises the use of all-sky cosmic microwave background, or correlations between large samples of galaxies, to determine information about the geometry of the Universe and hence the Hubble constant, typically in a combination with other cosmological parameters. Many, but not all, object-based measurements give H0H_0 values of around 72-74km/s/Mpc , with typical errors of 2-3km/s/Mpc. This is in mild discrepancy with CMB-based measurements, in particular those from the Planck satellite, which give values of 67-68km/s/Mpc and typical errors of 1-2km/s/Mpc. The size of the remaining systematics indicate that accuracy rather than precision is the remaining problem in a good determination of the Hubble constant. Whether a discrepancy exists, and whether new physics is needed to resolve it, depends on details of the systematics of the object-based methods, and also on the assumptions about other cosmological parameters and which datasets are combined in the case of the all-sky methods.Comment: Extensively revised and updated since the 2007 version: accepted by Living Reviews in Relativity as a major (2014) update of LRR 10, 4, 200

    Quando o silêncio é rompido: o processo de revelação e notificação de abuso sexual infantil When the silence is broken: the process of disclosure and reporting of child sexual abuse

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    O objetivo deste artigo é discutir o processo de revelação e notificação de situações de abuso sexual envolvendo crianças e adolescentes, a partir da análise de publicações relacionadas a essa temática. Os estudos indicam que a revelação e a notificação do abuso sexual são momentos difíceis para a vítima e para seus familiares porque geralmente envolvem alguém próximo à criança e apresentam reflexos no sistema familiar, como rompimento de vínculo, culpabilização e perda de suporte financeiro. Vários fatores que podem facilitar ou inibir a revelação e notificação do abuso são discutidos, como, por exemplo, a reação materna. Destaca-se a importância de um trabalho integrado no atendimento às vítimas, no encaminhamento das questões judiciais e no fortalecimento da rede de apoio às famílias.<br>The aim of this article is to discuss the process of disclosure and reporting of cases of sexual abuse involving children and adolescents, based on the analysis of publications related to that topic. Studies suggest that the disclosure and reporting of sexual abuse is a difficult moment for the victims and their families because it usually involves someone close to the child. It provokes changes in the family system, such as disruption of ties, guilt and loss in financial support. Several factors that may facilitate or inhibit the disclosure and reporting of sexual abuse are discussed such as the mother's reaction. It is highlighted the importance of an integrated work in the service that deals with these situations, involving the victims care, in the forwarding of the processes and in the strengthening of the supporting network for families
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