Detection of a Star Forming Galaxy in the Center of a Low-Mass Galaxy Cluster

Brightest Cluster Galaxies (BCGs) residing in the centers of galaxy clusters are typically quenched giant ellipticals. A recent study hinted that star-forming galaxies with large disks, so-called superluminous spirals and lenticulars, are the BCGs of a subset of galaxy clusters. Based on the existing optical data it was not possible to constrain whether the superluminous disk galaxies reside at the center of galaxy clusters. In this work, we utilize XMM-Newton X-ray observations of five galaxy clusters to map the morphology of the intracluster medium (ICM), characterize the galaxy clusters, determine the position of the cluster center, and measure the offset between the cluster center and the superluminous disk galaxies. We demonstrate that one superluminous lenticular galaxy, 2MASX J10405643-0103584, resides at the center of a low-mass ($M_{\rm 500} = 10^{14} \ \rm{M_{\odot}}$) galaxy cluster. This represents the first conclusive evidence that a superluminous disk galaxy is the central BCG of a galaxy cluster. We speculate that the progenitor of 2MASX J10405643-0103584 was an elliptical galaxy, whose extended disk was re-formed due to the merger of galaxies. We exclude the possibility that the other four superluminous disk galaxies reside at the center of galaxy clusters, as their projected distance from the cluster center is $150-1070$ kpc, which corresponds to $(0.27-1.18)R_{\rm 500}$. We conclude that these clusters host quiescent massive elliptical galaxies at their center.Comment: 7 pages, 3 figures, accepted for publication in the Astrophysical Journa

Dark Matter Subhalos and the X-ray Morphology of the Coma Cluster

Structure formation models predict that clusters of galaxies contain numerous massive subhalos. The gravity of a subhalo in a cluster compresses the surrounding intracluster gas and enhances its X-ray emission. We present a simple model, which treats subhalos as slow moving and gasless, for computing this effect. Recent weak lensing measurements by Okabe et al. have determined masses of ~ 10^13 solar masses for three mass concentrations projected within 300 kpc of the center of the Coma Cluster, two of which are centered on the giant elliptical galaxies NGC 4889 and NGC 4874. Adopting a smooth spheroidal beta-model for the gas distribution in the unperturbed cluster, we model the effect of these subhalos on the X-ray morphology of the Coma Cluster, comparing our results to Chandra and XMM-Newton X-ray data. The agreement between the models and the X-ray morphology of the central Coma Cluster is striking. With subhalo parameters from the lensing measurements, the distances of the three subhalos from the Coma Cluster midplane along our line of sight are all tightly constrained. Using the model to fit the subhalo masses for NGC 4889 and NGC 4874 gives 9.1 x 10^12 and 7.6 x 10^12 solar masses, respectively, in good agreement with the lensing masses. These results lend strong support to the argument that NGC 4889 and NGC 4874 are each associated with a subhalo that resides near the center of the Coma Cluster. In addition to constraining the masses and 3-d location of subhalos, the X-ray data show promise as a means of probing the structure of central subhalos.Comment: ApJ, in press. Matches the published versio

ROUSSEAU E OS LIMITES DA LEI NATURAL

The intention here is to articulate the critical elements of Rousseau's doctrine of natural law, as it appears in Hobbes and the natural law tradition.Pretende-se aqui articular os elementos da crítica de Rousseau à doutirna do direito natural, tal como ela aparece em Hobbes e na tradição jusnaturalista

Hugo Grotius: direito natural e dignidade

O artigo apresenta algumas idéias importantes do discurso dos direitos de Hugo Grotius. As definições de direito natural, appetitus socialis e dignidade

Democracia liberal: crise ou ruptura/declínio?

Crisis or rupture/decline? For some researchers, democracy continues to have wide appeal, but the commitment to it is not always very deep. This low level of commitment can create an environment of relative tolerance for actions that distort or break the rules of democracy. It could open the door to restrictions on free speech, excessive use of executive power, or even military intervention in politics. In view of this, is the equilibrium democracy model able to prevent the internal corrosion described by Steven Levitsky and Daniel Ziblatt, or the lack of interest in defending it in times of Amazon, internet and social networks, as David Runciman seems to suggest? In this article, I propose an approach to liberal democracy from the critique of a certain representation and idea of democracy presented by critical thinkers, in particular, the philosopher Jacques Rancière. Theorists who emphasized the importance of disagreement and the often sporadic nature of politics. These theories focus on a strong critique of existing minimalist democratic theories and practices. Rancière turns his critical attention to what he calls “consensual democracy”, the attempt to eliminate all forms of disagreement, and therefore politics, from the social body. The desire for consensual democracy is the desire for a politics that has eliminated disruptive democratic politics, to be replaced by apolitical administration and private domination, a desire perhaps felt in Fukuyama's end-of-history thesis and deeply linked to neoliberal ideology.Crise ou ruptura/declínio? Para alguns pesquisadores, a democracia continua a ter grande apelo, mas o compromisso com ela nem sempre é muito profundo. Esse baixo nível de comprometimento pode criar um ambiente de relativa tolerância para ações que distorcem ou quebram as regras da democracia. Pode abrir a porta para restrições à liberdade de expressão, uso excessivo do poder executivo ou mesmo intervenção militar na política. À vista disso, o modelo de democracia de equilíbrio é capaz de impedir a corrosão interna descrita por Steven Levitsky e Daniel Ziblatt, ou a falta de interesse em defendê-la em tempos de Amazon, internet e redes sociais, como parece sugerir David Runciman? Neste artigo, proponho uma abordagem da democracia liberal a partir da crítica de certa representação e ideia de democracia apresentada por pensadores críticos, em especial, o filósofo Jacques Rancière. Teóricos que enfatizaram a importância do desacordo e a natureza muitas vezes esporádica da política. Essas teorias se concentram em uma forte crítica das teorias e práticas democráticas minimalistas existentes. Rancière volta sua atenção crítica ao que ele chama de “democracia consensual”, tentativa de eliminar todas as formas de desacordo e, portanto, política, do corpo social. O desejo de democracia consensual é o desejo de uma política que eliminou a política democrática disruptiva, a ser substituída por administração apolítica e dominação privada, um desejo talvez sentido na tese do fim da história de Fukuyama e profundamente ligado à ideologia neoliberal

Jacques Rancière e a estética da ação criativa

Neste artigo discuto a definição de aisthesis proposta por Jacques Rancière. Os anos de 1996-98 marcaram um ponto de virada quando o interesse de Rancière mudou do político para o estético: primeiro para a literatura e depois para questões mais amplas de teoria estética e artes visuais. Na gênese dos escritos de Rancière, essa expansão da igualdade democrática, do político ao estético, é realizada em La Parole Muette. Todos os seus escritos estéticos posteriores, incluindo Le Destin des Images e La Fable Cinématographique, baseiam-se extensivamente nesses desenvolvimentos. Tanto na política quanto na estética, os escritos de Rancière nos oferecem uma rara e preciosa defesa da ação criativa

Luiz Felipe Netto de Andrade e Silva Sahd

Neste artigo, teremos por objeto a análise da expressão “teologia política” de Rousseau e algumas das discussões que surgiram a partir da retomada da classificação proposta por Marco Terêncio Varrão e presente em Giambattista Vico, mas cujo esquema foi se modificando na Ilustração numa perspectiva deísta. A nossa intenção é mostrar o debate fundamental em torno da apropriação da noção de teologia política no século XVIII e os seus efeitos no processo revolucionário

On the use of artificial neural networks in remotely piloted aircraft acquired images for estimating reservoir’s bathymetry

The use of acoustic systems for mapping submerged areas is the most accurate way. However, echosounders are expensive and, in addition, the equipment requires a great deal of experience on the part of the specialist. From another perspective, orbital and aerial images (acquired by RPA’s- Remotely Piloted Aircraft) can offer bathymetric maps of larger locations that are difficult to access at a low operating cost. Therefore, the present study’s main objective was to evaluate the utility of RGB images obtained with RPA’s in water reservoirs. Thus, Artificial Neural Networks were used for depth training and prediction. Subsequently, it compared to the bathymetric data from the same pond in question, raised from acoustic sensors, quantifying the vertical uncertainty through three estimators. Regarding the statistical analysis, the RMSE and Ф estimators showed better reliability. The 300-point sample showed the best quality in processing. The results showed that the methodology could improve the management of water resources. The method allows reduced execution time and lowers cost, especially for using only the green, red and blue channels, easily found in most cameras coupled to RPA’s