14 research outputs found
Paper 1: The JWST PEARLS View of the El Gordo Galaxy Cluster and of the Structure It Magnifies
The massive galaxy cluster El Gordo (z=0.87) imprints multitudes of
gravitationally lensed arcs onto James Webb Space Telescope (JWST)
Near-Infrared Camera (NIRCam) images. Eight bands of NIRCam imaging were
obtained in the ``Prime Extragalactic Areas for Reionization and Lensing
Science'' (``PEARLS'') program. PSF-matched photometry across Hubble Space
Telescope (HST) and NIRCam filters supplies new photometric redshifts. A new
light-traces-mass lens model based on 56 image multiplicities identifies the
two mass peaks and yields a mass estimate within 500 kpc of ~(7.0 +/- 0.30) x
10^14 Msun. A search for substructure in the 140 cluster members with
spectroscopic redshifts confirms the two main mass components. The southeastern
mass peak that contains the BCG is more tightly bound than the northwestern
one. The virial mass within 1.7 Mpc is (5.1 +/- 0.60) x 10^14 Msun, lower than
the lensing mass. A significant transverse velocity component could mean the
virial mass is underestimated. We contribute one new member to the previously
known z=4.32 galaxy group. Intrinsic (delensed) positions of the five secure
group members span a physical extent of ~60 kpc. Thirteen additional candidates
selected by spectroscopic/photometric constraints are small and faint with a
mean intrinsic luminosity ~2.2 mag fainter than L*. NIRCam imaging admits a
fairly wide range of brightnesses and morphologies for the group members,
suggesting a more diverse galaxy population in this galaxy overdensity.Comment: 24 pages, accepted by Ap
Iconografia tropical: motivos locais na arte colonial brasileira
Este artigo estuda a representação visual da natureza tropical na arte sacra do período colonial brasileiro, entre os séculos XVI e XVIII, época em que as artes visuais do país se desenvolveram no contexto do barroco introduzido pelos missionários católicos. Foi na decoração das igrejas que apareceram algumas das primeiras representações artísticas de elementos da natureza local, notadamente as frutas tropicais, produzindo novas combinações junto à tradicional ornamentação fitomórfica europeia, constituída de folhas de acantos e vinhas. Após um levantamento das ocorrências dessas manifestações da temática local na decoração dos templos presentes nas regiões nordeste e sudeste do país, este trabalho aborda, nos textos dos viajantes e missionários produzidos no período, as interpretações cristãs da natureza tropical que permitiram o aproveitamento desses motivos como parte da estratégia de pregação e conversão católica por meio da alegorização moral e religiosa da natureza do Novo Mundo.This paper studies the visual representation of local nature in the sacred art developed during the colonial period of Brazilian history. In this period, between the XVIth and the XVIIIth centuries, the visual arts in the country evolved in the context of the Baroque introduced by Catholic missionaries. It was in the decoration of the churches in which the first representations of aspects of local nature, mostly the tropical fruits, appeared in Brazilian visual arts, producing new combinations together with the traditional European phytomorphic ornamentation of acanthus leaves and grapes. This research draws upon texts written by travellers and missionaries during the period to demonstrate how the Europeans interpreted and represented tropical nature and used these representations as part of the Catholic preaching strategy by means of moral and religious allegorization of the New World nature
An architecture for authentication of mobile devices through a public key infrastructure.
A identificação de objetos que participam de uma arquitetura de processamento
de dados é uma preocupação relevante para a segurança das informações e fator
decisivo para a utilização de serviços que utilizam dados sensíveis. Este trabalho propõe
uma arquitetura para a autenticação de dispositivos móveis utilizando a Infra-estrutura
de Chave Pública (PKI) e o Protocolo de Iniciação de Sessões (SIP) de modo a
minimizar as limitações de armazenamento e processamento destes aparelhos.The identification of objects that participates of architecture of data processing is
a concern for information security and decisive factor for services that need manipulate
sensible data. This work considers architecture for mobile devices authentication
through in a Public Key Infrastructure and the Session Initiation Protocol (SIP) as a way
to minimize storage and processing limitations of those devices
A Smart Trust Management Method to Detect On-Off Attacks in the Internet of Things
Internet of Things (IoT) resources cooperate with themselves for requesting and providing services. In heterogeneous and complex environments, those resources must trust each other. On-Off attacks threaten the IoT trust security through nodes performing good and bad behaviors randomly, to avoid being rated as a menace. Some countermeasures demand prior levels of trust knowledge and time to classify a node behavior. In some cases, a malfunctioning node can be mismatched as an attacker. In this paper, we introduce a smart trust management method, based on machine learning and an elastic slide window technique that automatically assesses the IoT resource trust, evaluating service provider attributes. In simulated and real-world data, this method was able to identify On-Off attackers and fault nodes with a precision up to 96% and low time consumption
ALMA Lensing Cluster Survey: Deep 1.2 mm Number Counts and Infrared Luminosity Functions at
International audienceWe present a statistical study of 180 dust continuum sources identified in 33 massive cluster fields by the ALMA Lensing Cluster Survey (ALCS) over a total of 133 arcmin area, homogeneously observed at 1.2 mm. ALCS enables us to detect extremely faint mm sources by lensing magnification, including near-infrared (NIR) dark objects showing no counterparts in existing {\it Hubble Space Telescope} and {\it Spitzer} images. The dust continuum sources belong to a blind sample () with S/N 5.0 (a purity of 0.99) or a secondary sample () with S/N= screened by priors. With the blind sample, we securely derive 1.2-mm number counts down to Jy, and find that the total integrated 1.2mm flux is 20.7 Jy deg, resolving 80 % of the cosmic infrared background light. The resolved fraction varies by a factor of due to the completeness correction depending on the spatial size of the mm emission. We also derive infrared (IR) luminosity functions (LFs) at with the method, finding the redshift evolution of IR LFs characterized by positive luminosity and negative density evolution. The total (=UV+IR) cosmic star-formation rate density (SFRD) at is estimated to be % of the established measurements, which were almost exclusively based on opticalNIR surveys. Although our general understanding of the cosmic SFRD is unlikely to change beyond a factor of 2, these results add to the weight of evidence for an additional ( %) SFRD component contributed by the faint-mm population, including NIR dark objects
ALMA Lensing Cluster Survey: Deep 1.2 mm Number Counts and Infrared Luminosity Functions at
International audienceWe present a statistical study of 180 dust continuum sources identified in 33 massive cluster fields by the ALMA Lensing Cluster Survey (ALCS) over a total of 133 arcmin area, homogeneously observed at 1.2 mm. ALCS enables us to detect extremely faint mm sources by lensing magnification, including near-infrared (NIR) dark objects showing no counterparts in existing {\it Hubble Space Telescope} and {\it Spitzer} images. The dust continuum sources belong to a blind sample () with S/N 5.0 (a purity of 0.99) or a secondary sample () with S/N= screened by priors. With the blind sample, we securely derive 1.2-mm number counts down to Jy, and find that the total integrated 1.2mm flux is 20.7 Jy deg, resolving 80 % of the cosmic infrared background light. The resolved fraction varies by a factor of due to the completeness correction depending on the spatial size of the mm emission. We also derive infrared (IR) luminosity functions (LFs) at with the method, finding the redshift evolution of IR LFs characterized by positive luminosity and negative density evolution. The total (=UV+IR) cosmic star-formation rate density (SFRD) at is estimated to be % of the established measurements, which were almost exclusively based on opticalNIR surveys. Although our general understanding of the cosmic SFRD is unlikely to change beyond a factor of 2, these results add to the weight of evidence for an additional ( %) SFRD component contributed by the faint-mm population, including NIR dark objects