2D mapping of young stars in the inner 180 pc of NGC 1068: correlation with molecular gas ring and stellar kinematics

We report the first two-dimensional mapping of the stellar population and non-stellar continua within the inner 180 pc (radius) of NGC 1068 at a spatial resolution of 8 pc, using integral field spectroscopy in the near-infrared. We have applied the technique of spectral synthesis to data obtained with the instrument NIFS and the adaptive optics module ALTAIR at the Gemini North Telescope. Two episodes of recent star formation are found to dominate the stellar population contribution: the first occurred 300 Myr ago, extending over most of the nuclear region; the second occurred just 30 Myr ago, in a ring-like structure at ~100 pc from the nucleus, where it is coincident with an expanding ring of H2 emission. Inside the ring, where a decrease in the stellar velocity dispersion is observed, the stellar population is dominated by the 300 Myr age component. In the inner 35 pc, the oldest age component (age > 2Gyr) dominates the mass, while the flux is dominated by black-body components with temperatures in the range 700 < T < 800 K which we attribute to the dusty torus. We also find some contribution from black-body and power-law components beyond the nucleus which we attribute to dust emission and scattered light.Comment: Accepted for publication in Ap

PACCE: Perl Algorithm to Compute Continuum and Equivalent Widths

We present Perl Algorithm to Compute continuum and Equivalent Widths (pacce). We describe the methods used in the computations and the requirements for its usage. We compare the measurements made with pacce and "manual" ones made using iraf splot task. These tests show that for SSP models the equivalent widths strengths are very similar (differences <0.2A) for both measurements. In real stellar spectra, the correlation between both values is still very good, but with differences of up to 0.5A. pacce is also able to determine mean continuum and continuum at line center values, which are helpful in stellar population studies. In addition, it is also able to compute the uncertainties in the equivalent widths using photon statistics. The code is made available for the community through the web at http://www.if.ufrgs.br/~riffel/software.html.Comment: 8 pages, 5 figures, accepted by Astrophysics and Space Scienc

Influência da densidade ambiental na estrutura de discos de galáxias edge-on

Neste trabalho buscamos estudar a influencia da densidade ambiental sobre a estrutura de discos galácticos (fino e espesso). Estamos interessados em obter os parâmetros estruturais, como escalas de altura e de comprimento (radial) dos discos fino e espesso de galáxias em ambientes de alta densidade, como grupos compactos de Hickson e aglomerados Abell, e depois compará-los aos parâmetros de galáxias de campo. Para isto, apresentamos um modelo computacional bidimensional de discos galácticos, com diferentes frações relativas de brilho, para a obtenção dos parâmetros estruturais. O modelo foi testado com simulações e também comparado com resultados de ajuste de perfil feitos anteriormente. Este modelo é aplicado sobre nove galáxias, sendo uma de campo e oito em regiões de alta densidade. Através da analise de catálogos da literatura, obtemos contrastes de densidade ambientais para estas galáxias e assim, traçamos as relações entre estrutura e densidade ambiental. Estudamos também as mesmas relações para uma amostra disponível na literatura. Constatamos que não ha uma correlação visível entre as escalas horizontal e vertical dos discos galácticos e a densidade ambiental. Discutimos brevemente as conseqüências desses resultados para os modelos de efeitos ambientais.In this thesis we investigate the influence of environment density over the structure of galactic discs, both thin and thick. We are interested in extracting structural parameters, such as scalelengths and scaleheights, of discs in galaxies located in high density environments, such as Hickson Compact Groups and Abell clusters, in order to compare them to their counterparts in the field. For that purpose we developed a computational bidimensional model of galactic discs, of different brightnesses. The model was tested with simulations and also confronted to the results of previously done profile fitting. The model was applied to nine galaxies, one of them in the field and the remaining in high density regions. We used galaxy catalogs from the literature in order to estimate density contrasts around these galaxies. We then correlated these densities with disc structure parameters. We also studied the same relation for a sample available in the literature. We concluded that there is no clear correlation between scalelengths and scaleheights and environmental densities. Finally, we briefly discuss the consequences of these results for models that describe environmental effects

Influência da densidade ambiental na estrutura de discos de galáxias edge-on

Neste trabalho buscamos estudar a influencia da densidade ambiental sobre a estrutura de discos galácticos (fino e espesso). Estamos interessados em obter os parâmetros estruturais, como escalas de altura e de comprimento (radial) dos discos fino e espesso de galáxias em ambientes de alta densidade, como grupos compactos de Hickson e aglomerados Abell, e depois compará-los aos parâmetros de galáxias de campo. Para isto, apresentamos um modelo computacional bidimensional de discos galácticos, com diferentes frações relativas de brilho, para a obtenção dos parâmetros estruturais. O modelo foi testado com simulações e também comparado com resultados de ajuste de perfil feitos anteriormente. Este modelo é aplicado sobre nove galáxias, sendo uma de campo e oito em regiões de alta densidade. Através da analise de catálogos da literatura, obtemos contrastes de densidade ambientais para estas galáxias e assim, traçamos as relações entre estrutura e densidade ambiental. Estudamos também as mesmas relações para uma amostra disponível na literatura. Constatamos que não ha uma correlação visível entre as escalas horizontal e vertical dos discos galácticos e a densidade ambiental. Discutimos brevemente as conseqüências desses resultados para os modelos de efeitos ambientais.In this thesis we investigate the influence of environment density over the structure of galactic discs, both thin and thick. We are interested in extracting structural parameters, such as scalelengths and scaleheights, of discs in galaxies located in high density environments, such as Hickson Compact Groups and Abell clusters, in order to compare them to their counterparts in the field. For that purpose we developed a computational bidimensional model of galactic discs, of different brightnesses. The model was tested with simulations and also confronted to the results of previously done profile fitting. The model was applied to nine galaxies, one of them in the field and the remaining in high density regions. We used galaxy catalogs from the literature in order to estimate density contrasts around these galaxies. We then correlated these densities with disc structure parameters. We also studied the same relation for a sample available in the literature. We concluded that there is no clear correlation between scalelengths and scaleheights and environmental densities. Finally, we briefly discuss the consequences of these results for models that describe environmental effects

Deep surface photometry of edge-on spirals in Abell galaxy clusters constraining environmental effects

Two galaxies have a horizontal profile with a strong down-turn at outer radii, preventing a simple exponential from fitting the entire range. For the 2 early-type spirals, the thick discs have larger scalelengths than the thin discs, whereas no trend is seen for the later types. Both the thin and thick discs sampled tend to have similar scalelengths and scaleheights when compared to typical field disc galaxies. However, the thin disc parameters of the 2 farthest galaxies, both late-type spirals, may be significantly affected by seeing effects. Taken at face value, our results suggest that environment plays a minor role in determining the thin and thick disc sizes

Two-dimensional mapping of young stars in the inner 180 pc of NGC 1068 : correlation with molecular gas ring and stellar kinematics

We report the first two-dimensional mapping of the stellar population and non-stellar continua within the inner 180 pc (radius) of NGC 1068 at a spatial resolution of 8 pc, using integral field spectroscopy in the near-infrared. We have applied the technique of spectral synthesis to data obtained with the instrument NIFS and the adaptive optics module ALTAIR at the Gemini North Telescope. Two episodes of recent star formation are found to dominate the stellar population contribution: the first occurred 300 Myr ago, extending over most of the nuclear region; the second occurred just 30 Myr ago, in a ring-like structure at ≈100 pc from the nucleus, where it is coincident with an expanding ring of H2 emission. Inside the ring, where a decrease in the stellar velocity dispersion is observed, the stellar population is dominated by the 300 Myr age component. In the inner 35 pc, the oldest age component (age ≥ 2 Gyr) dominates the mass, while the flux is dominated by blackbody components with temperatures in the range 700 K ≤ T ≤ 800 K which we attribute to the dusty torus. We also find some contribution from blackbody and power-law components beyond the nucleus which we attribute to dust emission and scattered light

Hoja de predicción: Número 187 - 2004 Septiembre 27

We map the kinematics of the inner (200 pc) narrow-line region (NLR) of the Seyfert 2 galaxy NGC 1068 using the instrument Near-infrared Integral Field Spectrograph and adaptive optics at the Gemini North telescope. Channel maps and position–velocity diagrams are presented at a spatial resolution of ∼= 8 pc and spectral resolution ∼5300 in the emission lines [Fe II] λ1.644 μm, H2 λ2.122 μm and Brγ. The [Fe II] emission line provides a better coverage of the NLR outflow than the previously used [O III] λ5007 emission line, extending beyond the area of the bipolar cone observed in Brγ and [O III]. This is mainly due to the contribution of the redshifted channels to the north-east of the nucleus, supporting its origin in a partial ionized zone with additional contribution from shocks of the outflowing gas with the galactic disc. We modelled the kinematics and geometry of the [Fe II] emitting gas finding good agreement with the data for outflow models with conical and lemniscate (or hourglass) geometry.We calculate a mass outflow rate of 1.9+2 −1 M yr−1 but a power for the outflow of only 0.08 per cent LBol. The molecular (H2) gas kinematics is completely distinct from that of [Fe II] and Brγ , showing radial expansion in an off-centred ∼100 pc radius ring in the galaxy plane. The expansion velocity decelerates from ≈200 km s−1 in the inner border of the ring to approximately zero at the outer border where our previous studies found a 10 Myr stellar population

Two-dimensional mapping of young stars in the inner 180 pc of NGC 1068 : correlation with molecular gas ring and stellar kinematics

We report the first two-dimensional mapping of the stellar population and non-stellar continua within the inner 180 pc (radius) of NGC 1068 at a spatial resolution of 8 pc, using integral field spectroscopy in the near-infrared. We have applied the technique of spectral synthesis to data obtained with the instrument NIFS and the adaptive optics module ALTAIR at the Gemini North Telescope. Two episodes of recent star formation are found to dominate the stellar population contribution: the first occurred 300 Myr ago, extending over most of the nuclear region; the second occurred just 30 Myr ago, in a ring-like structure at ≈100 pc from the nucleus, where it is coincident with an expanding ring of H2 emission. Inside the ring, where a decrease in the stellar velocity dispersion is observed, the stellar population is dominated by the 300 Myr age component. In the inner 35 pc, the oldest age component (age ≥ 2 Gyr) dominates the mass, while the flux is dominated by blackbody components with temperatures in the range 700 K ≤ T ≤ 800 K which we attribute to the dusty torus. We also find some contribution from blackbody and power-law components beyond the nucleus which we attribute to dust emission and scattered light