Stellar population gradients in normal and active galaxies
Autor(a) principal: | |
---|---|
Data de Publicação: | 2001 |
Outros Autores: | , , |
Tipo de documento: | Artigo |
Idioma: | eng |
Título da fonte: | Repositório Institucional da UFRGS |
Texto Completo: | http://hdl.handle.net/10183/89971 |
Resumo: | We use high signal-to-noise ratio long-slit spectra in the λλ3500–7000-Å range of three early-type (Hubble type S0) normal, two low-ionization nuclear emission region (LINER) and three Seyfert 2 galaxies to make a comparative study of the variation of the stellar population properties as a function of distance from the nucleus. In order to characterize the stellar population and other continuum sources (e.g. featureless continuum) we have measured equivalent widths (Ws) of six absorption features, continuum colours and their radial variations, and performed spectral population synthesis as a function of distance from the nucleus. The Ws for the normal galaxies are strongest at the nucleus and decrease outwards. The two LINER galaxies show a similar behaviour, but with the nuclear Ws in the blue (λ < 4500 Å) ~~ 10–20 per cent smaller. Both normal galaxies and LINERs present a redder nucleus than their surroundings. The three Seyfert 2 galaxies present the opposite behaviour, with most Ws in the blue being smaller at the nucleus, which is also bluer than outside. By combining the results of the present work with those of a previous study, we conclude that, in a sample of 12 Seyfert 2s of Hubble type S0, 10 (~~ 80 per cent) present nuclear Ws smaller than those of normal galaxies, while at ~~ 1 kpc from the nucleus this number decreases to 4 (~~30 per cent). Sampling regions of ~~ 100–200 pc, we conclude that the normal galaxies have nuclear stellar populations dominated by the components with an age of 10 Gyr and metallicity solar or above. The contribution of this component decreases, while that of 1 Gyr increases, with increasing distance from the nucleus. The LINERs present a similar behaviour but have a ~~ 10–20 per cent larger contribution of the 1-Gyr component at the nucleus. For the Seyfert 2 galaxies, there are additional components: in the three cases studied here, there is a significant contribution from a 100-Myr-old population at the nucleus plus featureless continuum in two cases and also of a 3-Myr-old component in Mrk463E. Outside the nucleus, the stellar population is similar to that of normal galaxies in ESO138-G1, but it has an excess of old metal-poor components in NGC7743 and of young components in Mrk463E, when compared with normal galaxies. The reddening of the continuum is lowest in the normal galaxy nuclei [E (B-V)i ~~ 0.00] and highest in the Seyfert [E (B-V)i ~~ 0.20] nuclei. |
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Raimann, Daniel IunesStorchi-Bergmann, ThaisaBica, Eduardo Luiz DamianiAlloin, Danielle Marie2014-03-29T01:51:40Z20010035-8711http://hdl.handle.net/10183/89971000292125We use high signal-to-noise ratio long-slit spectra in the λλ3500–7000-Å range of three early-type (Hubble type S0) normal, two low-ionization nuclear emission region (LINER) and three Seyfert 2 galaxies to make a comparative study of the variation of the stellar population properties as a function of distance from the nucleus. In order to characterize the stellar population and other continuum sources (e.g. featureless continuum) we have measured equivalent widths (Ws) of six absorption features, continuum colours and their radial variations, and performed spectral population synthesis as a function of distance from the nucleus. The Ws for the normal galaxies are strongest at the nucleus and decrease outwards. The two LINER galaxies show a similar behaviour, but with the nuclear Ws in the blue
(λ < 4500 Å) ~~ 10–20 per cent smaller. Both normal galaxies and LINERs present a redder nucleus than their surroundings. The three Seyfert 2 galaxies present the opposite behaviour, with most Ws in the blue being smaller at the nucleus, which is also bluer than outside. By combining the results of the present work with those of a previous study, we conclude that, in a sample of 12 Seyfert 2s of Hubble type S0, 10 (~~ 80 per cent) present nuclear Ws smaller than those of normal galaxies, while at ~~ 1 kpc from the nucleus this number decreases to 4 (~~30 per cent). Sampling regions of ~~ 100–200 pc, we conclude that the normal galaxies have nuclear stellar populations dominated by the components with an age of 10 Gyr and metallicity solar or above. The contribution of this component decreases, while that of 1 Gyr increases, with increasing distance from the nucleus. The LINERs present a similar behaviour but have a ~~ 10–20 per cent larger contribution of the 1-Gyr component at the nucleus. For the Seyfert 2 galaxies, there are additional components: in the three cases studied here, there is a significant contribution from a 100-Myr-old population at the nucleus plus featureless continuum in two cases and also of a 3-Myr-old component in Mrk463E. Outside the nucleus, the stellar population is similar to that of normal galaxies in ESO138-G1, but it has an excess of old metal-poor components in NGC7743 and of young components in Mrk463E, when compared with normal galaxies. The reddening of the continuum is lowest in the normal galaxy nuclei [E
(B-V)i ~~ 0.00] and highest in the Seyfert [E
(B-V)i ~~ 0.20] nuclei.application/pdfengMonthly notices of the Royal Astronomical Society. Oxford. Vol. 324, no. 4 (July 2001), p. 1087-1101Galáxias ativasGaláxiasGalaxias seyfertEstrelasGalaxies: activeGalaxies: generalGalaxies: seyfertGalaxies: stellar contentStellar population gradients in normal and active galaxiesEstrangeiroinfo:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/openAccessreponame:Repositório Institucional da UFRGSinstname:Universidade Federal do Rio Grande do Sul (UFRGS)instacron:UFRGSORIGINAL000292125.pdf000292125.pdfTexto completo (inglês)application/pdf1291405http://www.lume.ufrgs.br/bitstream/10183/89971/1/000292125.pdfca407d7bbdfca4260cfc784e5eade0e8MD51TEXT000292125.pdf.txt000292125.pdf.txtExtracted Texttext/plain45460http://www.lume.ufrgs.br/bitstream/10183/89971/2/000292125.pdf.txtb9d9a50082229f3f7908ffa705c25273MD52THUMBNAIL000292125.pdf.jpg000292125.pdf.jpgGenerated Thumbnailimage/jpeg1770http://www.lume.ufrgs.br/bitstream/10183/89971/3/000292125.pdf.jpgd345930b69e07eb2f2d18f7089b3ce0bMD5310183/899712024-04-13 06:46:30.512812oai:www.lume.ufrgs.br:10183/89971Repositório de PublicaçõesPUBhttps://lume.ufrgs.br/oai/requestopendoar:2024-04-13T09:46:30Repositório Institucional da UFRGS - Universidade Federal do Rio Grande do Sul (UFRGS)false |
dc.title.pt_BR.fl_str_mv |
Stellar population gradients in normal and active galaxies |
title |
Stellar population gradients in normal and active galaxies |
spellingShingle |
Stellar population gradients in normal and active galaxies Raimann, Daniel Iunes Galáxias ativas Galáxias Galaxias seyfert Estrelas Galaxies: active Galaxies: general Galaxies: seyfert Galaxies: stellar content |
title_short |
Stellar population gradients in normal and active galaxies |
title_full |
Stellar population gradients in normal and active galaxies |
title_fullStr |
Stellar population gradients in normal and active galaxies |
title_full_unstemmed |
Stellar population gradients in normal and active galaxies |
title_sort |
Stellar population gradients in normal and active galaxies |
author |
Raimann, Daniel Iunes |
author_facet |
Raimann, Daniel Iunes Storchi-Bergmann, Thaisa Bica, Eduardo Luiz Damiani Alloin, Danielle Marie |
author_role |
author |
author2 |
Storchi-Bergmann, Thaisa Bica, Eduardo Luiz Damiani Alloin, Danielle Marie |
author2_role |
author author author |
dc.contributor.author.fl_str_mv |
Raimann, Daniel Iunes Storchi-Bergmann, Thaisa Bica, Eduardo Luiz Damiani Alloin, Danielle Marie |
dc.subject.por.fl_str_mv |
Galáxias ativas Galáxias Galaxias seyfert Estrelas |
topic |
Galáxias ativas Galáxias Galaxias seyfert Estrelas Galaxies: active Galaxies: general Galaxies: seyfert Galaxies: stellar content |
dc.subject.eng.fl_str_mv |
Galaxies: active Galaxies: general Galaxies: seyfert Galaxies: stellar content |
description |
We use high signal-to-noise ratio long-slit spectra in the λλ3500–7000-Å range of three early-type (Hubble type S0) normal, two low-ionization nuclear emission region (LINER) and three Seyfert 2 galaxies to make a comparative study of the variation of the stellar population properties as a function of distance from the nucleus. In order to characterize the stellar population and other continuum sources (e.g. featureless continuum) we have measured equivalent widths (Ws) of six absorption features, continuum colours and their radial variations, and performed spectral population synthesis as a function of distance from the nucleus. The Ws for the normal galaxies are strongest at the nucleus and decrease outwards. The two LINER galaxies show a similar behaviour, but with the nuclear Ws in the blue
(λ < 4500 Å) ~~ 10–20 per cent smaller. Both normal galaxies and LINERs present a redder nucleus than their surroundings. The three Seyfert 2 galaxies present the opposite behaviour, with most Ws in the blue being smaller at the nucleus, which is also bluer than outside. By combining the results of the present work with those of a previous study, we conclude that, in a sample of 12 Seyfert 2s of Hubble type S0, 10 (~~ 80 per cent) present nuclear Ws smaller than those of normal galaxies, while at ~~ 1 kpc from the nucleus this number decreases to 4 (~~30 per cent). Sampling regions of ~~ 100–200 pc, we conclude that the normal galaxies have nuclear stellar populations dominated by the components with an age of 10 Gyr and metallicity solar or above. The contribution of this component decreases, while that of 1 Gyr increases, with increasing distance from the nucleus. The LINERs present a similar behaviour but have a ~~ 10–20 per cent larger contribution of the 1-Gyr component at the nucleus. For the Seyfert 2 galaxies, there are additional components: in the three cases studied here, there is a significant contribution from a 100-Myr-old population at the nucleus plus featureless continuum in two cases and also of a 3-Myr-old component in Mrk463E. Outside the nucleus, the stellar population is similar to that of normal galaxies in ESO138-G1, but it has an excess of old metal-poor components in NGC7743 and of young components in Mrk463E, when compared with normal galaxies. The reddening of the continuum is lowest in the normal galaxy nuclei [E
(B-V)i ~~ 0.00] and highest in the Seyfert [E
(B-V)i ~~ 0.20] nuclei. |
publishDate |
2001 |
dc.date.issued.fl_str_mv |
2001 |
dc.date.accessioned.fl_str_mv |
2014-03-29T01:51:40Z |
dc.type.driver.fl_str_mv |
Estrangeiro info:eu-repo/semantics/article |
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http://hdl.handle.net/10183/89971 |
dc.language.iso.fl_str_mv |
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dc.relation.ispartof.pt_BR.fl_str_mv |
Monthly notices of the Royal Astronomical Society. Oxford. Vol. 324, no. 4 (July 2001), p. 1087-1101 |
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openAccess |
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