A near infrared photometric plane for ellipticals and bulges of spirals

We report the existence of a single plane in the space of global photometric parameters describing elliptical galaxies and the bulges of early type spiral galaxies. The three parameters which define the plane are obtained by fitting the Sersic form to the brightness distribution obtained from near-infrared K band images. We find, from the range covered by their shape parameters, that the elliptical galaxies form a more homogeneous population than the bulges. Known correlations like the Kormendy relation are projections of the photometric plane. The existence of the plane has interesting implications for bulge formation models.Comment: 12 pages, LaTeX including 5 figures. To appear in the Astrophysical Journal Letter

A New Empirical Model for the Structural Analysis of Early-type Galaxies and a Critical Review of the Nuker Model

The Nuker law was designed to match the inner few (~3-10) arcseconds of predominantly nearby (< 30 Mpc) early-type galaxy light-profiles; it was never intended to describe an entire profile. The Sersic model, on the other hand, was developed to fit the entire profile; however, due to the presence of partially depleted galaxy cores, the Sersic model cannot always describe the very inner region. We have therefore developed a new empirical model consisting of an inner power-law, a transition region, and an outer Sersic model to connect the inner and outer structure of elliptical galaxies. Moreover, the stability of the Nuker model parameters are investigated. Surprisingly, none are found to be stable quantities; all are shown to vary systematically with a profile's fitted radial extent, and often by more than 100%. Considering elliptical galaxies spanning a range of 7.5 magnitudes, the central stellar density of the underlying host galaxy is observed to increase with galaxy luminosity until the onset of core formation, detected only in the brightest elliptical galaxies. We suggest that the so-called ``power-law'' galaxies may actually be described by the Sersic model over their entire radial range

Extremely Red Objects in Two Quasar Fields at z ~ 1.5

We present an investigation of the properties and environments of bright extremely red objects (EROs) found in the fields of the quasars TXS 0145+386 and 4C 15.55, both at z ~ 1.4. There is marginal evidence from Chandra ACIS imaging for hot cluster gas with a luminosity of a few 10^44 ergs/s in the field of 4C 15.55. The TXS 0145+386 field has an upper limit at a similar value, but it also clearly shows an overdensity of faint galaxies. None of the EROs are detected as X-ray sources. For two of the EROs that have spectral-energy distributions and rest-frame near-UV spectra that show that they are strongly dominated by old stellar populations, we determine radial-surface-brightness profiles from adaptive-optics images. Both of these galaxies are best fit by profiles close to exponentials, plus a compact nucleus comprising ~30% of the total light in one case and 8% in the other. Neither is well fit by an r^1/4-law profile. This apparent evidence for the formation of massive ~2 X 10^11 disks of old stars in the early universe indicates that at least some galaxies formed essentially monolithically, with high star-formation rates sustained over a few 10^8 years, and without the aid of major mergers.Comment: 25 pages, 13 figures, accepted to Ap

Correlations among global photometric properties of disk galaxies

Using a two-dimensional galaxy image decomposition technique, we extract global bulge and disk parameters for a complete sample of early type disk galaxies in the near infrared K band. We find significant correlation of the bulge parameter n with the central bulge surface brightness $\mu_b(0)$ and with effective radius r_e. Using bivar iate analysis techniques, we find that $\log n$, $\log r_e$ and $\mu_b(0)$ are distributed in a plane with small scatter. We do not find a strong correlation of n with bulge-to-disk luminosity ratio, contrary to earlier reports. r_e and the disk scale length r_d are well correlated for these early type disk galaxies, but with large scatter. We examine the implications of our results to various bulge formation scenarios in disk galaxies.Comment: 14 pages, LaTeX including 14 figures. To appear in the Astrophysical Journa

The stellar host in blue compact dwarf galaxies: the need for a two-dimensional fit

The structural properties of the low surface brightness stellar host in blue compact dwarf galaxies are often studied by fitting r^{1/n} models to the outer regions of their radial profiles. The limitations imposed by the presence of a large starburst emission overlapping the underlying component makes this kind of analysis a difficult task. We propose a two-dimensional fitting methodology in order to improve the extraction of the structural parameters of the LSB host. We discuss its advantages and weaknesses by using a set of simulated galaxies and compare the results for a sample of eight objects with those already obtained using a one-dimensional technique. We fit a PSF convolved Sersic model to synthetic galaxies, and to real galaxy images in the B, V, R filters. We restrict the fit to the stellar host by masking out the starburst region and take special care to minimize the sky-subtraction uncertainties. In order to test the robustness and flexibility of the method, we carry out a set of fits with synthetic galaxies. Furthermore consistency checks are performed to assess the reliability and accuracy of the derived structural parameters. The more accurate isolation of the starburst emission is the most important advantage and strength of the method. Thus, we fit the host galaxy in a range of surface brightness and in a portion of area larger than in previous published 1D fits with the same dataset. We obtain robust fits for all the sample galaxies, all of which, except one, show Sersic indices n very close to 1, with good agreement in the three bands. These findings suggest that the stellar hosts in BCDs have near-exponential profiles, a result that will help us to understand the mechanisms that form and shape BCD galaxies, and how they relate to the other dwarf galaxy classes.Comment: 22 pages, 15 figures (low resolution), accepted for publication in A&A. A higher resolution version of the figures can be provided upon reques

Old and young bulges in late-type disk galaxies

ABRIDGED: We use HSTACS and NICMOS imaging to study the structure and colors of a sample of nine late-type spirals. We find: (1) A correlation between bulge and disks scale-lengths, and a correlation between the colors of the bulges and those of the inner disks. Our data show a trend for bulges to be more metal-enriched than their surrounding disks, but otherwise no simple age-metallicity connection between these systems; (2) A large range in bulge stellar population properties, and, in particular, in stellar ages. Specifically, in about a half of the late-type bulges in our sample the bulk of the stellar mass was produced recently. Thus, in a substantial fraction of the z=0 disk-dominated bulged galaxies, bulge formation occurs after the formation/accretion of the disk; (3) In about a half of the late-type bulges in our sample, however, the bulk of the stellar mass was produced at early epochs; (4) Even these "old" late-type bulges host a significant fraction of stellar mass in a young(er) c component; (5) A correlation for bulges between stellar age and stellar mass, in the sense that more massive late-type bulges are older than less massive late-type bulges. Since the overall galaxy luminosity (mass) also correlates with the bulge luminosity (mass), it appears that the galaxy mass regulates not only what fraction of itself ends up in the bulge component, but also "when" bulge formation takes place. We show that dynamical friction of massive clumps in gas-rich disks is a plausible disk-driven mode for the formation of "old" late-type bulges. If disk evolutionary processes are responsible for the formation of the entire family of late-type bulges, CDM simulations need to produce a similar number of initially bulgeless disks in addition to the disk galaxies that are observed to be bulgeless at z=0.Comment: ApJ in press; paper with high resolution figures available at http://www.exp-astro.phys.ethz.ch/carollo/carollo1_2006.pdf; B, I, and H surface brightness profiles published in electronic tabular for

A Correlation between Light Concentration and Cluster Local Density for Elliptical Galaxies

Using photometric and redshift data for the Virgo and Coma clusters, we present evidence for a correlation between the light concentration of elliptical galaxies (including dwarf ellipticals) and the local 3-D (i.e. non-projected) density of the clusters: more concentrated ellipticals are located in denser regions. The null hypothesis (i.e. the absence of any relation) is rejected at a significance level better than 99.9%. In order to explain the observed relation, a power law relating the galaxy light concentration and the cluster 3-D density is proposed. We study how the projection effects affect the form and dispersion of the data-points in the light concentration-projected density diagram. The agreement between our model and the observed data suggests that there is a paucity of dwarf elliptical galaxies in the cluster central regions.Comment: 7 pages, 2 figures, ApJL accepte

The Luminosity Profiles of Brightest Cluster Galaxies

(Abridged) We have derived detailed R band luminosity profiles and structural parameters for a total of 430 brightest cluster galaxies (BCGs), down to a limiting surface brightness of 24.5 mag/arcsec^2. Light profiles were initially fitted with a Sersic's R^(1/n) model, but we found that 205 (~48) BCGs require a double component model to accurately match their light profiles. The best fit for these 205 galaxies is an inner Sersic model, with indices n~1-7, plus an outer exponential component. Thus, we establish the existence of two categories of the BCGs luminosity profiles: single and double component profiles. We found that double profile BCGs are brighter ~0.2 mag than single profile BCG. In fact, the Kolmogorov-Smirnov test applied to these subsamples indicates that they have different total magnitude distributions, with mean values M_R=-23.8 +/- 0.6 mag for single profile BCGs and M_R=-24.0 +/- 0.5 mag for double profile BCGs. We find that partial luminosities for both subsamples are indistinguishable up to r = 15 kpc, while for r > 20 kpc the luminosities we obtain are on average 0.2 mag brighter for double profile BCGs. This result indicates that extra-light for double profile BCGs does not come from the inner region but from the outer regions of these galaxies. The best fit slope of the Kormendy relation for the whole sample is a = 3.13 +/- 0.04$. However, when fitted separately, single and double profile BCGs show different slopes: a_(single) = 3.29 +/- 0.06 and a_(double)= 2.79 +/- 0.08. On the other hand, we did not find differences between these two BCGs categories when we compared global cluster properties such as the BCG-projected position relative to the cluster X-ray center emission, X-ray luminosity, or BCG orientation with respect to the cluster position angle.Comment: August 2011 issue of ApJS, volume 195, 15 http://iopscience.iop.org/0067-0049/195/2/1

Os desafios da docência no ensino superior frente a inclusão de pessoas com deficiência nas universidades

Talk about the educational inclusion of people with disabilities (PCD) is not exactly a new theme in the Brazilian scenario. Taking the 1988 Federal Constitution as a legal and historical landmark, it can be said that for at least 30 years the issue of educational inclusion has been gaining prominence in the field of educational policies, research in education and teaching practices. On the other hand, when we deal with inclusion in Higher Education we face a contrary situation. Both public policies and knowledge production are very recent, which configures the inclusion of PCD in Higher Education still an open field, with many research fronts, in different areas of knowledge. One of the most important research themes is teaching in higher education and the challenges teachers face facing the inclusion of PCD in universities. Considering the above theme, the article aims to reflect on how much the access of students with disabilities in Higher Education, especially from the policy of reserving vacancies (Law 13.409 / 2016), has impacted the daily life of the classrooms. particularly in teaching practices. We will conduct a systematic literature review, based on a search in the Scielo database (Scientific Electronic Library Online), between 2008 and 2018, searching for articles on higher education teaching and the inclusion of PCD. The texts will be quantified and qualitatively analyzed, seeking to identify the challenges found in the context of teaching in Higher Education facing inclusion.Abordar la inclusión educativa de las personas con discapacidad (PCD) no es exactamente un tema nuevo en el escenario brasileño. Tomando la Constitución Federal de 1988 como un hito legal e histórico, se puede decir que durante al menos 30 años el tema de la inclusión educativa ha ido ganando importancia en el campo de las políticas educativas, la investigación en educación ensino las prácticas de enseñanza. Por otro lado, cuando tratamos con la inclusión en la educación superior, nos enfrentamos a una situación contraria. Tanto las políticas públicas como la producción de conocimiento son muy recientes, lo que configura la inclusión de PCD en la educación superior, que sigue siendo un campo abierto, con muchos frentes de investigación, en diferentes áreas de conocimiento. Uno de los temas de investigación más importantes es la enseñanza en educación superior ensino los desafíos que enfrentan los docentes frente a la inclusión de PCD en las universidades. Teniendo en cuenta el tema anterior, el artículo pretende reflexionar sobre el impacto que ha tenido en la vida diaria de los estudiantes con discapacidades en la educación superior, especialmente a partir de la política de reservar lugares (Ley 13.409 / 2016). Particularmente en las prácticas de enseñanza. Llevaremos a cabo una revisión bibliográfica sistemática, basada en una búsqueda en la base de datos Scielo (Scientific Electronic Library Online), entre 2008 ensino 2018, en busca de artículos sobre enseñanza de educación superior ensino la inclusión de PCD. Los textos se cuantificarán ensino se analizarán cualitativamente, buscando identificar los desafíos encontrados en el contexto de la enseñanza en la Educación Superior que enfrenta la inclusión.Tratar da inclusão educacional de pessoas com deficiência (PCD) não é propriamente um tema novo no cenário brasileiro. Tomando a Constituição Federal de 1988 como marco legal e histórico, é possível afirmar que, há pelo menos 30 anos, a temática da inclusão educacional vem ganhando relevo no campo das políticas educacionais, da investigação em educação e das práticas docentes. Por outro lado, quando tratamos da inclusão no ensino superior nos deparamos com uma situação contrária. Tanto as políticas públicas quanto a produção de conhecimento são muito recentes, o que configura a inclusão de PCD no ensino superior ainda um campo aberto, com muitas frentes de pesquisa, nas diferentes áreas do conhecimento. Um dos temas de investigação que se impõem é a docência no ensino superior e os desafios que os professores enfrentam frente à inclusão de PCD nas universidades. Considerando o tema exposto, o artigo tem como objetivo fazer uma reflexão sobre o quanto o acesso de estudantes com deficiência no ensino superior, em especial a partir da política de reserva de vagas (Lei 13.409/2016), tem impactado no cotidiano das salas de aula, em particular nas práticas docentes. Realizamos uma revisão de literatura, a partir de uma pesquisa na base de dados do Scielo (Scientific Electronic Library Online), entre 2008 e 2018, buscando por artigos sobre a docência no ensino superior e a inclusão de PCD. Os textos foram quantificados e analisados qualitativamente, buscando identificar os desafios encontrados no contexto da docência no ensino superior frente à inclusão. A complexidade envolvida no processo de inclusão de PCD no ensino superior é grande, em especial no que toca à atuação do docente. Os artigos nos sinalizam diferentes desafios à prática docente que vão desde a sua postura diante de estudantes com deficiência até a sua capacidade de ressignificar e modificar a sua prática tendo a inclusão como um princípio pedagógico