AGN spiral galaxies in groups: effects of bars

AIMS: We explore properties of barred active spiral galaxies in groups and clusters selected from the Sloan Digital Sky Survey data release 7 (SDSS-DR7), with the aim of assessing the effects of bars on active galactic nuclei (AGN) and the role of the high density environment. METHODS: We identified barred active galaxies that reside in groups and clusters by cross-correlating the total barred AGN sample with the SDSS-DR7 group catalog. With the goal of providing a suitable quantification of the effects of bars, a reliable control sample of unbarred active galaxies in high density environments with similar redshift, magnitude, morphology, and bulge size distributions was also constructed. RESULTS: We found that the fraction of barred AGN galaxies in groups and clusters (≈38%) is higher than those in the total barred AGN sample (≈28%), indicating that AGN spiral galaxies in groups are more likely to be barred than those in the field. We also found that barred AGN galaxies are more concentrated towards the group centers than the other unbarred AGN group members. In addition, barred AGN host galaxies show an excess of population dominated by red colors, with respect to the control sample, suggesting that bars produce an important effect on galaxy colors of AGN hosts. The groups of AGN galaxies with and without bars show similar virial masses; however, the host groups of the barred AGN exhibit a larger fraction of red colors than the host groups of the corresponding unbarred active galaxies in the control sample. Color-magnitude relations of both host groups of AGN differ significantly: the host group colors of barred active galaxies display distributions spreading toward red populations, at the same (Mr)Group, with respect to the host groups of the unbarred AGN objects. This trend is more significant in less massive groups than in groups with MVirial> 1013.5M⊙. Barred active galaxies show an excess of nuclear activity compared to galaxies without bars in the control sample. We found that barred active galaxies located farther from the group-center have stronger Lum[OIII], while the nuclear activity in AGN galaxies without bars remain approximately constant with the group-centric distance. In addition, for both AGN samples, nuclear activity increases in bluer host groups however, barred active objects systematically show higher Lum[OIII] values, irrespective of the global group colors. Our findings suggest that the efficiency of bars to transport material towards the more central regions of the AGN galaxies in high density environments reveals an important dependence on the localization of objects within the group/cluster and on the host group colors.Fil: Alonso Giraldes, Maria Sol. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Coldwell Lloveras, Georgina Vanesa. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Garcia Lambas, Diego Rodolfo. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; Argentin

Occurrence of LINER galaxies within the galaxy group environment

We study the properties of a sample of 3967 low-ionization nuclear emission-line region (LINER) galaxies selected from SDSS-DR7, with respect to their proximity to galaxy groups. The host galaxies of LINERs have been analysed and compared with a well-defined control sample of 3841 non-LINER galaxies matched in redshift, luminosity, colour, morphology, age and stellar mass content. We find no difference between LINER and control galaxies in terms of the colour and age of stellar population as a function of the virial mass and distance to the geometric centre of the group. However, we find that LINERs are more likely to populate low-density environments in spite of their morphology, which is typical of high-density regions such as rich galaxy clusters. For rich (poor) galaxy groups, the occurrence of LINERs is approximately two times lower (higher) than the occurrence of matched, non-LINER galaxies. Moreover, LINER hosts do not seem to follow the expected morphology–density relation in groups of high virial mass. The high frequency of LINERs in low-density regions could be due to the combination of a sufficient gas reservoir to power the low-ionization emission and/or enhanced galaxy interaction rates benefiting the gas flow towards their central regions.Fil: Coldwell Lloveras, Georgina Vanesa. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Geofísica y Astronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Pereyra, Luis Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Alonso Giraldes, Maria Sol. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Geofísica y Astronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Donoso, Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio. Universidad Nacional de San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio; ArgentinaFil: Duplancic Videla, Maria Fernanda. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Geofísica y Astronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Galaxias espirales de núcleos activos: efecto de las barras en la actividad nuclear

En este trabajo se analizan galaxias espirales barreadas con núcleos activos (AGN), con el propósito de realizar estudios estadísticos acerca del efecto que pudiesen producir las barras sobre la actividad de los agujeros negros centrales. Para tal fin, construimos una muestra de galaxias AGN con barras, clasificadas por medio de inspección visual, a partir del séptimo relevamiento de Sloan Digital Sky Survey (SDSS-DR7). Además, se obtuvo una muestra de galaxias espirales AGN no-barreadas, con similares distribuciones de corrimiento al rojo, luminosidad y masa en estrellas que las galaxias AGN barreadas. Se presentan resultados preliminares del efecto de las barras sobre la actividad nuclear central, explorando diferentes propiedades de las galaxias espirales barreadas huéspedes de AGN, en comparación con su contraparte de galaxias no-barreadas.In this work we analyze barred active galactic nuclei galaxies (AGN), in order to study the effect produced by the bars on the central black hole activity. We construct a sample of AGN galaxies with bars, classified by visual inspection, from the seventh release of Sloan Digital Sky Survey (SDSS-DR7). In addition, we construct a non-barred AGN galaxy sample with similar redshift distributions, luminosity and mass in stars than barred AGN galaxies. We present preliminary results of the effect of bars on the central nuclear activity, exploring different properties of barred spiral AGN galaxies, compared to its counterpart in non-barred galaxies.Fil: Alonso Giraldes, Maria Sol. Consejo Nacional de Investigaciones Cientiâ­ficas y Tecnicas. Centro Cientifico Tecnologico San Juan. Instituto de Ciencias Astronomicas de la Tierra y del Espacio; Argentina. Universidad Nacional de San Juan; ArgentinaFil: Coldwell Lloveras, Georgina Vanesa. Consejo Nacional de Investigaciones Cientiâ­ficas y Tecnicas. Centro Cientifico Tecnologico San Juan. Instituto de Ciencias Astronomicas de la Tierra y del Espacio; Argentina. Universidad Nacional de San Juan; Argentin

Determinação e identificação dos compostos voláteis no queijo de Évora ao longo da maturação

As características do aroma do queijo estão associadas aos compostos voláteis formados durante a maturação. A microextracção em fase sólida permite o isolamento destes compostos da matriz. Avaliaram-se as fibras carboxeno/polidimetilsiloxano, polidimetilsiloxano /divinilbenzeno e polidimetilsiloxano, efectuando a extracção do espaço de cabeça de uma mistura modelo. Seleccionou-se a fibra polidimetilsiloxano/divinilbenzeno para a extracção dos compostos voláteis do queijo, a sua separação e identificação realizou-se por cromatografia gasosa - espectrometria de massa. Na identificação recorreu-se à ionização por impacto electrónico, ionização química e à espectrometria de massa em múltiplas etapas. A composição volátil do queijo de Évora foi avaliada em três fases da maturação; encontraram-se 20 compostos. Entre a primeira e as restantes fases observam-se diferenças qualitativas, entre a segunda e a terceira detectam-se apenas diferenças quantitativas. Para comparação do perfil global do aroma nas diferentes fases, recorreu-se ao nariz electrónico. Obteve-se uma diferenciação entre a primeira fase e as duas restantes. ***/Abstract - The character of cheese aroma is related to volatile compounds formed during ripening. Solid phase microextraction allows the isolation of these compounds from the matrix. The carboxen/polydimethylsiloxane, polydimethylsiloxane/divinylbenzene and polydimethylsiloxane fibres were evaluated through headspace extraction of a model mixture. The polydimethylsiloxane/divinylbenzene fibre was chosen for extraction of volatile compounds from cheese, the separation and identification was done by gas chromatography - mass spectrometry. For identification electron impact, chemical ionization and tandem mass spectrometry were employed. The composition in volatiles of Évora cheese was evaluated in three stages of ripening; 20 compounds were found. Qualitative differences were observed between the first and the following two stages, quantitative differences were detected between the second and third stages. For comparison of the global aroma profile of the individual stages, the electronic nose was used. A separation between the first stage and the following two was attained

Natural IgM secretion in health and disease : genetic control and role in type 1 diabetes

Tese de Doutoramento em Ciências Veterinárias, especialidade de Ciências Biológicas e BiomédicasGermline-encoded autoreactive natural antibodies (NAbs) of the IgM isotype are secreted and circulate as a result of basal immune system stimulation, and constitute an important first line of defense against microorganism invasion, bridging the innate and the adaptive immune responses. NAbs are mostly secreted by positively selected B1a cells, and have been claimed to have a protective role against autoimmunity. Nevertheless, NAbs binding to cell surface self-antigens could have implications in the initiation of autoimmunity. Article I focused on the genetic control of NAbs secretion in healthy mice. Importantly, interferon regulatory factor 4 (Irf4), a transcription factor required for plasma cell differentiation and antibody secretion, was identified as the most probable candidate for the control of homeostatic serum IgM levels in the mouse. Type 1 diabetes (T1D) is a complex autoimmune disease that develops spontaneously in humans and is pathogenically similar in the non-obese-diabetic (NOD) mouse model. B cells are necessary in the NOD diabetogenic process, and the presence of anti-pancreatic beta cell antibodies is the earliest manifestation of T1D. Article II revealed that NOD peritoneal cavity B1a cells are more prone to spontaneously secrete NAbs that recognize pancreatic beta cell autoantigens, which could promote T1D either by enhancing professional antigen presentation of islet antigens, by activating the complement cascade or by directly promoting beta cell damage and self-antigens release. The studies reported in article III have explored these possibilities and have proven that NAbs of NOD B1a cells origin could bind and directly induce oxidative stress on pancreatic beta cells. Moreover, these studies have shown that NOD B1a cells have a lower threshold for innate-like stimulation and have established a link between NOD B1a cells properties, NAbs specificities and impact of IgM binding on beta cells physiology. Finally, article IV provides evidence that early treatment with antibodies that evoke NOD B1a cells proliferation and differentiation into IgM secreting cells correlates with T1D precipitation. In conclusion, this thesis has shown that Irf4 is a critical player in the genetic network that controls IgM secretion in healthy individuals, and that in the NOD mouse model of T1D, a lower threshold for innate like stimulation of peritoneal cavity B1a cells contributes to a naturally increased state of B1a cells activation and autoreactive IgM secretion, determining the initiation and/or contributing to the fueling of beta cells autoimmunity.RESUMO Secreção de IgM natural na saúde e na doença: controlo genético e papel na diabetes tipo 1 - Os autoanticorpos naturais (NAbs) da classe IgM existem no organismo na ausência de imunização e constituem uma primeira linha de defesa fundamental contra infecções. Os NAbs são secretados maioritariamente por células B1a e a sua ligação a autoantigénios na superfície celular pode ter implicações para a iniciação de autoimunidade. O trabalho descrito no artigo I focou-se na compreensão do controlo genético da secreção de NAbs em murganhos saudáveis. Este estudo identificou o interferon regulatory factor 4 (Irf4), um factor de transcrição necessário para a diferenciação de plasmócitos e secreção de anticorpos, como o candidato mais provável para o controlo da homeostasia dos níveis de IgM circulante no murganho. A diabetes tipo 1 (T1D) é uma doença autoimune complexa que se desenvolve espontaneamente nos humanos e que tem uma patogenia semelhante no murganho NOD (non-obese-diabetic). Os linfócitos B são necessários para o processo diabético do NOD, em que a presença de anticorpos anti-células beta pancreáticas é uma das manifestações mais precoces. O artigo II revelou que as células B1a da cavidade peritoneal do NOD têm uma elevada predisposição para secretarem NAbs que reconhecem autoantigénios de células beta pancreáticas e que podem promover o desenvolvimento de T1D quer pelo aumento da apresentação de autoantigénios, quer pela activação da cascata do sistema de complemento, quer pela indução directa de danos nas células beta pancreáticas. A investigação descrita no artigo III provou que os NAbs secretados por células B1a do NOD têm a capacidade de se ligarem e induzirem stress oxidativo nas células beta do pâncreas. Estes estudos revelaram ainda que as células B1a do NOD têm um limiar reduzido para activação inata e estabeleceram uma relação entre as propriedades das células B1a do NOD, as especificidades dos NAbs e o impacto da ligação de IgM na fisiologia das células beta. Finalmente, o artigo IV evidenciou que a indução de proliferação e diferenciação das células B1a em células secretoras de IgM contribui para o início da T1D. Esta tese demonstrou que o Irf4 é um factor de transcrição com um papel fundamental no controlo da secreção de IgM em animais saudáveis e que, no murganho NOD, as células B1a da cavidade peritoneal têm um menor limiar para estimulação inata, que contribui para o seu estado de activação e para a secreção de IgM autoreactiva, determinando a iniciação e/ou contribuindo para a progressão da diabetes tipo 1.Fundação para a Ciência e Tecnologia; Instituto Gulbenkian da Ciênci

LINER galaxy properties and the local environment

We analyse the properties of a sample of 5560 low-ionization nuclear emission-line region (LINER) galaxies selected from SDSS-DR12 at lowred shift, for a complete range of local density environments. The host LINER galaxies were studied and compared with a well-defined control sample of 5553 non-LINER galaxies matched in red shift, luminosity, morphology and local density. By studying the distributions of galaxy colours and the stellar age population, we find that LINERs are redder and older than the control sample over a wide range of densities. In addition, LINERs are older than the control sample, at a given galaxy colour, indicating that some external process could have accelerated the evolution of the stellar population. The analysis of the host properties shows that the control sample exhibits a strong relation between colours, ages and the local density, while more than 90 per cent of the LINERs are redder and older than the mean values, independently of the neighbourhood density. Furthermore, a detailed study in three local density ranges shows that, while control sample galaxies are redder and older as a function of stellar mass and density, LINER galaxies mismatch the known morphology-density relation of galaxies without low-ionization features. The results support the contribution of hot and old stars to the low-ionization emission although the contribution of nuclear activity is not discarded.Fil: Coldwell Lloveras, Georgina Vanesa. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Geofísica y Astronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Alonso Giraldes, Maria Sol. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Geofísica y Astronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Duplancic Videla, Maria Fernanda. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Geofísica y Astronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Mesa, Valeria Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentin

Major and minor mergers: global star formation efficiency

Se realizó un análisis de interacciones mayores y menores seleccionadas a partir del catálogo espectroscópico Sloan Digital Sky Survey (SDSSDR7). Se construyó una muestra de galaxias en pares cercanos aplicando el límite de separaciones proyectadas, rp By visual inspection of SDSS images we removed false identifications and we classify the interactions into three categories: pairs undergoing merging, M; pairs with evident tidal features, T; and non disturbed, N.We also divide the pair sample into minor and major interactions according to the luminosity ratio of the galaxy members. We conclude that the characteristics of the interactions and the ratio of luminosity galaxy pair members involved in a merger are important parameters in setting galaxy properties.Fil: Mesa, Valeria Alejandra. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico San Juan. Instituto de Ciencias Astronomicas de la Tierra y del Espacio; ArgentinaFil: Alonso Giraldes, Maria Sol. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico San Juan. Instituto de Ciencias Astronomicas de la Tierra y del Espacio; ArgentinaFil: Garcia Lambas, Diego Rodolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: O'Mill, Ana Laura. Universidade de Sao Paulo; Brasil. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto de Astronomía Teórica y Experimental; Argentin

Galaxy triplets in Sloan Digital Sky Survey Data Release 7: II. A connection with compact groups?

We analyse a sample of 71 triplets of luminous galaxies derived from the work of O´Mill et al. We compare the properties of triplets and their  members with those of control samples of compact groups, the 10 brightest members of rich clusters and galaxies in pairs. The triplets are restricted to have members with spectroscopic redshifts in the range 0.01<=z<=0.14 and absolute r-band luminosities brighter than Mr=-20.5. For these member galaxies, we analyse the stellar mass content, the star formation rates, the Dn(4000) parameter and (Mg-Mr) colour index. Since galaxies in triplets may finally merge in a single system, we analyse different global properties of these systems. We calculate the probability that the properties of galaxies in triplets are strongly correlated. We also study total star formation activity and global colours, and define the triplet compactness as a measure of the percentage of the system total area that is filled by the light of member galaxies. We concentrate in the comparison of our results with those of compact groups to assess how the triplets are a natural extension of these compact systems. Our analysis suggests that triplet galaxy members behave similarly to  compact group members and galaxies in rich clusters.We also find that systems comprising three blue, star-forming, young stellar population galaxies (blue triplets) are most probably real systems and not a chance configuration of interloping galaxies. The same holds for triplets  composed of three red, non-star-forming galaxies, showing the correlation of galaxy properties in these systems. From the analysis of the triplet as a whole, we conclude that, at a given total stellar mass content, triplets show a total star formation activity and global colours similar to compact groups. However, blue triplets show a high total star formation activity with a lower stellar mass content. From an analysis of the compactness parameter of the systems we find that light is even more concentrated in triplets than in compact groups. We propose that triplets composed of three luminous galaxies, should not be considered as an analogous of galaxy pairs with a third extra member, but rather they are a natural extension of compact groups.Fil: Duplancic Videla, Maria Fernanda. Consejo Nacional de Investigaciones Cientiâ­ficas y Tecnicas. Centro Cientifico Tecnologico San Juan. Instituto de Ciencias Astronomicas de la Tierra y del Espacio; ArgentinaFil: O'mill, Ana Laura. Universidade Do Sao Paulo. Instituto Astronomia, Geofisica E Ciencias Atmosfericas. Departamento de Astronomia; BrasilFil: Garcia Lambas, Diego Rodolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Sodré Jr., Laerte. Universidade Do Sao Paulo. Instituto Astronomia, Geofisica E Ciencias Atmosfericas. Departamento de Astronomia; BrasilFil: Alonso Giraldes, Maria Sol. Consejo Nacional de Investigaciones Cientiâ­ficas y Tecnicas. Centro Cientifico Tecnologico San Juan. Instituto de Ciencias Astronomicas de la Tierra y del Espacio; Argentin