ABSTRACT
We present spatially resolved stellar population (SP) age maps, average radial profiles and gradients for the first 62 active galactic nuclei (AGN) observed with Sloan Digital Sky Survey ...(SDSS)-IV Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) to study the effects of the active nuclei on the star formation history of the host galaxies. These results, derived using the starlight code, are compared with a control sample of non-active galaxies matching the properties of the AGN hosts. We find that the fraction of young SPs in high-luminosity AGN is higher in the inner (R$\rm \le 0.5\,$Re) regions when compared with the control sample; low-luminosity AGN, on the other hand, present very similar fractions of young stars to the control sample hosts for the entire studied range (1 Re). The fraction of intermediate-age SP of the AGN hosts increases outwards, with a clear enhancement when compared with the control sample. The inner region of the galaxies (AGN and control galaxies) presents a dominant old SP, whose fraction decreases outwards. We also compare our results (differences between AGN and control galaxies) for the early- and late-type hosts and find no significant differences. In summary, our results suggest that the most luminous AGN seems to have been triggered by a recent supply of gas that has also triggered recent star formation (t ≤ 40 Myr) in the central region.
We present spatially resolved stellar population age maps, average radial profiles and gradients for the first 62 Active Galactic Nuclei (AGN) observed with SDSS-IV MaNGA to study the effects of the ...active nuclei on the star formation history of the host galaxies. These results, derived using the STARLIGHT code, are compared with a control sample of non-active galaxies matching the properties of the AGN hosts. We find that the fraction of young stellar populations (SP) in high-luminosity AGN is higher in the inner (\(R \leq 0.5\,R_e\)) regions when compared with the control sample; low-luminosity AGN, on the other hand, present very similar fractions of young stars to the control sample hosts for the entire studied range (\(1\,R_e\)). The fraction of intermediate age SP of the AGN hosts increases outwards, with a clear enhancement when compared with the control sample. The inner region of the galaxies (AGN and control galaxies) presents a dominant old SP, whose fraction decreases outwards. We also compare our results (differences between AGN and control galaxies) for the early and late-type hosts and find no significant differences. In summary, our results suggest that the most luminous AGN seems to have been triggered by a recent supply of gas that has also triggered recent star formation (\(t\,\leq\,40\,Myrs\)) in the central region.
As propriedades dinâmicas e populacionais do aglomerado de galáxias LCDCS-S001 são analisadas mediante imageamento e espectroscopia de multi-objetos obtidos com o instrumento GMOS do obervatório ...Gemini Sul. Através da espectroscopia de uma amostra de objetos selecionados atrav´es de imageamento na banda i’, confirmamos que LCDCS-S001 é um aglomerado de galáxias a redshift z=0.709. Síntese de populações estelares foi realizada para doze membros confirmados, através das medidas de índices espectroscópicos, usando os modelos de Bruzual & Charlot (2003) como espectros de base. Encontramos que as melhores soluções são aquelas com metalicidade solar, e que a maior parte das estrelas que compõem as galáxias estudadas é evoluída (t 3 Gyrs). Três galáxias da amostra apresentam contribuição significativa em fluxo (> 30%) de populações estelares com 1Gyrs. Em seis objetos, encontramos contribuição de populações estelares jovens (t 0.1 Gyrs), associada a formação estelar recente. A proporção de estrelas jovens na população estelar das galáxias aumenta conforme aumenta a distância das galáxias ao centro do aglomerado. Emissão OIIλ3727 foi encontrada em quatro objetos, todos mostrando, na síntese, contribuição importante de populações estelares jovens. As larguras equivalentes de OIIλ3727 foram comparadas com os modelos de Magris, Binette & Bruzual (2003) para regiões HII, e encontramos boa correspondência para escalas de tempo de formação estelar entre 1.0 e 3.0 Gyrs. Em termos morfológicos, encontramos que os esferóides mapeiam melhor a estrutura do aglomerado, estando as galáxias de disco localizadas preferencialmente na periferia, e concluímos que cerca de 10% das galáxias do aglomerado são esferoidais, com raio efetivo típico de 10-15 kpc. Em termos de massa, encontramos que as três galáxias mais massivas encontram-se no centro do aglomerado. As velocidades relativas dos membros confirmados foram usadas na estimativa da massa projetada do aglomerado, e encontramos 3.54+2.33 −1.41 ×1014M⊙. A distribuição bidimensional dos objetos mostrou que o aglomerado apresenta uma morfologia alongada. Sobredensidades locais foram identificadas na imagem i’, uma das quais provavelmente fazendo parte do aglomerado. Este fato sugere que LCDCS-S001 está sofrendo um processo de fusão. Essa hipótese é fortalecida pela identificação de uma fonte de rádio em 1.4 GHz no centrodo aglomerado, com uma alta potência monocromática, característica de halos rádio encontrados em aglomerados que vivenciam processos de instabilidade dinâmica.
The dynamical and populational properties of the cluster of galaxies LCDCS-S001 are analysed through imaging and multi-object spectroscopy obtained with the GMOS instrument of the Gemini South Observatory. By means of spectroscopy of a sample of objects selected in a i’ band image, we have confirmed that LCDCS-S001 is a cluster of galaxies at redshift z=0.709. Stellar population synthesis has been applyed for twelve confirmed members, through the measured spectroscopic indices, using the models of Bruzual & Charlot (2003) as template spectra. We have found that the best solutions are those with solar metallicity, and that most of the stars which constitute the studied galaxies are evolved (t 3Gyrs). Three galaxies of the sample present significant flux contribution (> 30%) of stellar populations with 1 Gyrs. In six objects, we have found a contribution of young stellar populations (t 0.1 Gyrs), associated to recent star formation. The proportion of young stars in the stellar population of the galaxies becomes higher as the distance of the galaxies to the cluster center rises. OIIλ3727 emission was found in four objects, all of which show strong contribution in the synthesis of young stellar populations. The equivalent widths of OIIλ3727 have been compared to the models of Magris, Binette & Bruzual (2003) for HII regions, and we have found a good correspondence for star formation timescales between 1.0 and 3.0 Gyrs. In morphological terms, we have found that the spheroids map better the structure of the cluster, the disk galaxies populating prefearably the peripherical regions, and we have concluded that around 10% of the cluster galaxies are spheroids,undergo dynamical instabilities.with a typical effective radius of 10-15 kpc. In terms of mass, we have found that the three most massive galaxies lay at the cluster center. The relative velocities of the confirmed members have been used to estimate the projected mass of the cluster, and we found 3.54+2.33 −1.41 × 1014M⊙. The two-dimensional distribution of the objects has shown that the cluster presents an alongated morphology. Local overdensities have been identified in the i’ image, one of which probably being part of the cluster. This fact suggests that LCDCS-S001 is undergoing a fusion process. This hypotesis is strengthened by the identification of a radio source in 1.4 GHz in the cluster center, with a high monochromatic power, characteristic of radio halos found in clusters which undergo dynamical instabilities.
PDF