The Relationship Between the Sersic Law Profiles Measured Along the Major and Minor Axes of Elliptical Galaxies

In this paper we discuss the reason why the parameters of the Sersic model best-fitting the major axis light profile of elliptical galaxies can differ significantly from those derived for the minor axis profile. We show that this discrepancy is a natural consequence of the fact that the isophote eccentricity varies with the radius of the isophote and present a mathematical transformation that allows the minor axis Sersic model to be calculated from the major axis model, provided that the elliptical isophotes are aligned and concentric and that their eccentricity can be represented by a well behaved, though quite general, function of the radius. When there is no variation in eccentricity only the effective radius changes in the Sersic model, while for radial-dependent eccentricity the transformation which allows the minor axis Sersic model to be calculated from the major axis model is given by the Lerch Phi transcendental function. The proposed transformation was tested using photometric data for 28 early-type galaxies.Comment: 16 pages, 14 figures, LaTex with mn2e.cls. Accepted to MNRA

Gas inflows towards the nucleus of the active galaxy NGC7213

We present two-dimensional stellar and gaseous kinematics of the inner 0.8x1.1kpc^2 of the LINER/Seyfert 1 galaxy NGC7213, from optical spectra obtained with the GMOS integral field spectrograph on the Gemini South telescope at a spatial resolution of 60pc. The stellar kinematics shows an average velocity dispersion of 177km/s, circular rotation with a projected velocity amplitude of 50km/s and a kinematic major axis at a position angle of -4degrees (west of north). From the average velocity dispersion we estimate a black hole mass of M_BH=8_{-6}^{+16}x10^7 M_sun. The gas kinematics is dominated by non-circular motions, mainly along two spiral arms extending from the nucleus out to 4arcsec (280pc) to the NW and SE, that are cospatial with a nuclear dusty spiral seen in a structure map of the nuclear region of the galaxy. The projected gas velocities along the spiral arms show blueshifts in the far side and redshifts in the near side, with values of up to 200km/s. This kinematics can be interpreted as gas inflows towards the nucleus along the spiral arms if the gas is in the plane of the galaxy. We estimate the mass inflow rate using two different methods. The first is based of the observed velocities and geometry of the flow, and gives a mass inflow rate in the ionised gas of 7x10^-2 M_sun/yr. In the second method, we calculate the net ionised gas mass flow rate through concentric circles of decreasing radii around the nucleus resulting in mass inflow rates ranging from 0.4 M_sun/yr at 300pc down to 0.2 M_sun/yr at 100pc from the nucleus. These rates are larger than necessary to power the active nucleus.Comment: 10 pages, 10 figures, accepted for publication in MNRA

Morfometryka and the search for constraints on galaxy morphometry

Morfometryka is a standalone python application that makes photometry and morphometry a easy task. It is designed to be used in large datasets. By combining Morfometryka and Machine Learning we are able to reproduce human classification using only a small set of independent features that actually have physical meaning

Otimização termodinâmica de sistemas de refrigeração solar

Orientador: José Viriato Coelho VargasCo-orientador: José Alberto dos Reis PariseDissertação (mestrado) - Universidade Federal do Paraná, Setor de Tecnologia, Programa de Pós-Graduação em Engenharia Mecânica. Defesa: Curitiba, 2005Inclui bibliografia e anexosRESUMO: Este trabalho apresenta uma contribuição para o entendimento de sistemas de refrigeração ou de condicionamento de ar alimentados por energia solar com uma forma de determinar a maneira como as taxas de refrigeração, fluxos de massa e as áreas de transferência de calor se relacionam. A intenção é tomar possível a identificação das regras preliminares de projeto. É considerado o problema termodinâmico básico de como obter a máxima taxa de entrada de exergia em um refrigerador alimentado por energia solar. É analisada a existência de uma razão ótima de vazões mássicas dos fluidos de trabalho para máxima refrigeração. A análise prossegue relacionando a taxa de geração de entropia, os parâmetros físicos e de operação, e as restrições físicas do sistema, através dos princípios fundamentais de transferência de calor. Finalmente, uma análise termodinâmica determina as características ótimas que levam à mínima geração de entropia. A eficiência de segunda lei da Termodinâmica é considerada como sendo a figura de mérito apropriada para determinação do ótimo termodinâmico do sistema.ABSTRACT: This work attempts to contribute to the understanding of the behavior of solar-driven refrigeration and air conditioning system by correlating refrigeration rate, mass flows and heat transfer areas in order to allow the identification of preliminary design rules. The basic thermodynamic problem of how to obtain maximum exergy input rate in a solar-driven refrigerator is considered. The occurrence of an optimal refrigerant flow rate for maximum refrigeration is investigated. The analysis proceeds by correlating the entropy generation rate, the physical and operating parameters, and the physical constraints of the system, through well-established heat transfer relationships. Finally, a thermodynamic analysis determines the optimal characteristics that lead to minimum entropy generation. The second law efficiency is identified as the appropriate figure of merit for the thermodynamic optimum

The benchmark black hole in NGC 4258: dynamical models from high-resolution two-dimensional stellar kinematics

NGC 4258 is the galaxy with the most accurate (maser-based) determination for the mass of the supermassive black hole (SMBH) in its nucleus. In this work we present a two-dimensional mapping of the stellar kinematics in the inner 3.0 x 3.0 arcsec = 100 x 100 pc of NGC 4258 using adaptative-optics observations obtained with the Near-Infrared Integral Field Spectrograph of the GEMINI North telescope at a 0.11 arcsec (4 pc) angular resolution. The observations resolve the radius of influence of the SMBH, revealing an abrupt increase in the stellar velocity dispersion within 10 pc from the nucleus, consistent with the presence of a SMBH there. Assuming that the galaxy nucleus is in a steady state and that the velocity dispersion ellipsoid is aligned with a cylindrical coordinate system, we constructed a Jeans anisotropic dynamical model to fit the observed kinematics distribution. Our dynamical model assumes that the galaxy has axial symmetry and is constructed using the multi-gaussian expansion method to parametrize the observed surface brightness distribution. The Jeans dynamical model has three free parameters: the mass of the central SMBH, the mass-luminosity ratio of the galaxy and the anisotropy of the velocity distribution. We test two types of models: one with constant velocity anisotropy, and another with variable anisotropy. The model that best reproduces the observed kinematics was obtained considering that the galaxy has radially varying anisotropy, being the best-fitting parameters with 3$\sigma$ significance $M_\bullet=4.8^{+0.8}_{-0.9}\times 10^7\,{\rm M_\odot}$ and $\Gamma_k = 4.1^{+0.4}_{-0.5}$. This value for the mass of the SMBH is just 25 per cent larger than that of the maser determination and 50 per cent larger that a previous stellar dynamical determination obtained via Schwarzschild models.Comment: Accepted for publication in MNRAS, 19 pages, 19 figure

Envolvimento de usuários em projeto de edifícios – revisão do estado da arte

Este artigo reporta os resultados de uma revisão sistemática de literatura sobre as definições e níveis de envolvimento de usuários no processo de projeto. Embora muitos estudos tenham ressaltado a importância do envolvimento de usuários para a qualidade tanto do processo quanto do produto final, o termo ainda não possui uma definição clara, e diferentes modelos descrevem diversos níveis de envolvimento, o que dificulta a consolidação do conhecimento nesta área. O presente estudo foca o mapeamento das definições de envolvimento de usuários e comparações das diferentes propostas de níveis de envolvimento, para delinear uma definição clara do termo, baseada nos níveis de envolvimento, e contribuir para a consolidação da teoria de envolvimento do usuário na área de projeto de arquitetura. Além disto, a presente pesquisa auxilia arquitetos a encontrar o nível de envolvimento de usuário mais apropriado ao projeto que desenvolvem, contribuindo para a melhoria desta prática.This paper reports results of a systematic literature review on the definitions and levels of user involvement in the design process. Although many studies have highlighted the importance of user involvement for the quality of both process and final product, the term still lacks a clear definition and different models describe diverse involvement levels, which are detrimental to the advancement of knowledge in the area. The present study focused on the mapping of definitions of user involvement and comparisons of the different proposals of involvement levels for outlining a clear definition of the term, based on the levels of involvement, and contributing to the consolidation of the theory of user involvement in the field of architectural design.  Moreover, this research assists architects to find the most appropriate level of user involvement for the design they are developing, improving the practice of involving users in the design process

Gas inflows towards the nucleus of the Seyfert 2 galaxy NGC 1667

We use optical spectra from the inner 2 × 3 kpc2 of the Seyfert 2 galaxy NGC 1667, obtained with the Gemini Multi-Object Spectrograph integral field spectrograph on the Gemini South telescope at a spatial resolution of ≈240 pc, to assess the feeding and feedback processes in this nearby active galactic nucleus (AGN). We have identified two gaseous kinematical components in the emission line profiles: a broader component (σ ≈ 400 km s−1) that is observed in the inner 1–2 arcsec and a narrower component (σ ≈ 200 km s−1) that is present over the entire field of view.We identify the broader component as due to an unresolved nuclear outflow. The narrower component velocity field shows strong isovelocity twists relative to a rotation pattern, implying the presence of strong non-circular motions. The subtraction of a rotational model reveals that these twists are caused by outflowing gas in the inner ≈1 arcsec, and by inflows associated with two spiral arms at larger radii.We calculate an ionized gas mass outflow rate of ˙Mout ≈ 0.16 M yr−1. We calculate the net gas mass flow rate across a series of concentric rings, obtaining a maximum mass inflow rate in ionized gas of ≈2.8 M yr−1 at 800 pc from the nucleus, which is two orders of magnitude larger than the accretion rate necessary to power this AGN. However, as the mass inflow rate decreases at smaller radii, most of the gas probably will not reach the AGN, but accumulate in the inner few hundred parsecs. This will create a reservoir of gas that can trigger the formation of new stars