On the hot interstellar medium of high-redshift galaxies

Detalhes bibliográficos
Autor(a) principal: Alegre, Lara Sofia Gorgulho
Data de Publicação: 2017
Tipo de documento: Dissertação
Idioma: eng
Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
Texto Completo: http://hdl.handle.net/10451/31293
Resumo: Tese de mestrado, Física (Astrofísica e Cosmologia) Universidade de Lisboa, Faculdade de Ciências, 2017
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spelling On the hot interstellar medium of high-redshift galaxiesGaláxiasEvoluçãoElevado redshiftMeio interestelarLinhas de emissãoObservaçõesTeses de mestrado - 2017Departamento de FísicaTese de mestrado, Física (Astrofísica e Cosmologia) Universidade de Lisboa, Faculdade de Ciências, 2017At high redshift, galaxies are very different from the ones in the local Universe. They present several high ionization ultraviolet emission lines such as Civ, Oiii] and Ciii], besides Heii which is associated with young and massive stars. The energy required for the production of emission lines like Civ was once only associated to Active Galactic Nuclei (AGNs). However, photoionization models have shown that these lines can be produced by star forming galaxies (SFGs) holding very hot and young stellar populations with a low metal content. The properties of high-redshift galaxies are not fully understood and the discrimination between these galaxies and AGNs is essential for their understanding. Recently, diagnostic diagrams using ultraviolet emission lines started being developed, however they are based on single stellar populations, which cannot reproduce the spectral energy distribution of these galaxies. In this work we produce and present three sets of models of nebular emission that allow to interpret and distinguish SFGs and AGNs, using the photoionization simulation code cloudy. We created a set of cloudy models using black bodies with a broad range of temperatures (20000 - 150000 K), densities (102 - 105 cm-3) and metallicities (1 – 10-5 Zʘ), which span from ionization parameters logU ~ -1 to -4.5. This provides a set of models with well known input parameters. Models below ~ 70000K can reproduce SFGs while the ones with higher temperature go into the classical AGN regime. To simulate AGNs we create another set of models based on power laws with slopes from -1.2 to -2.0 within the same range of densities and metallicities. Thirdly, for SFGs we used the state-of-the-art binary stellar evolutionary models bpass.v2 (Binary Population And Spectral Synthesis code). It is thought that at least ~ 70% of stars live in binary systems. Binary interactions which account for rotation effects are extremely important to understand the spectral energy distribution of these galaxies. In particular, for low metallicity systems, at which binary interactions promote dynamically mass transfer between the stars contrarily to high metallicity systems where the binary tends to become a wide structure. We present emission-line ratios diagnosis diagrams based on Ciii], Oiii], Civ and Heii] using our photoionization models. These diagrams allow to discriminate between SFGs and AGNs and at the same time provide a tool for unveiling the physical properties of these sources. We apply the modelling results to a population of 10 analogues of high redshift galaxies at z ~2 - 3 selected by their UV continuum. We found that these galaxies are better described by our bpass models holding young stellar populations with ages ~ 106:4 - 106:8 yrs, ionization parameters ~ logU = -2.21 , low stellar metallicities ~ 0.2 - 0.1 Z_ and very low gas metallicities ~ 0.004 Zʘ. We used the results obtained for these galaxies to calculate optical emission lines fluxes for [Oiii], [Oii], Hα and Hβ. These emission line fluxes can probe metal poor SFGs at high redshift to be observed with upcoming telescopes such as the James Webb Space telescope, and further test the validity of bpass models to explain these sources. We then analyse 6 bright Lyα emitters at the same range of redshifts, and we found that 3 of these systems are also better described by our bpass models. They are consistent with being analogues of high redshift galaxies, in particular 2 galaxies which present young ages (~ 106:3 - 106:5 yrs), higher ionization parameter (logU = -1.84 to -1.74) and lower stellar metallicity (< 0.1 Zʘ) than the previous UV continuum selected galaxies. We then use our models to understand the absence of metal lines in bright LAEs at redshifts up to z = 6 - 7, and we conclude that most of these sources require deeper observations. Lastly, we analyse galaxies from the HiZELS survey, selected with narrow band filters by their bright H_ emission line. We analyse a total of 425 spectra obtained with follow-up VIMOS (VLT) spectroscopy and we calculated the spectroscopic redshifts of 87 galaxies and AGNs. We found bright ionization ultraviolet lines in 2 of these galaxies at z ~ 1.5 and we estimate that these galaxies present extreme properties similar to the z ~ 2 - 3 bright LAEs analysed before. Our models provide a tool to discriminate between the nature of the galaxies, and estimate their physical properties. Our results are highly important to understand the properties of young galaxies now being found at the epoch of reionization. We aim to make all our modelling results fully public so it can benefit a wider community.Sobral, David Ricardo Serrano GonçalvesRepositório da Universidade de LisboaAlegre, Lara Sofia Gorgulho2018-01-31T15:30:42Z201720172017-01-01T00:00:00Zinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/masterThesisapplication/pdfhttp://hdl.handle.net/10451/31293TID:201870509enginfo:eu-repo/semantics/openAccessreponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãoinstacron:RCAAP2023-11-08T16:24:51Zoai:repositorio.ul.pt:10451/31293Portal AgregadorONGhttps://www.rcaap.pt/oai/openaireopendoar:71602024-03-19T21:46:51.603445Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãofalse
dc.title.none.fl_str_mv On the hot interstellar medium of high-redshift galaxies
title On the hot interstellar medium of high-redshift galaxies
spellingShingle On the hot interstellar medium of high-redshift galaxies
Alegre, Lara Sofia Gorgulho
Galáxias
Evolução
Elevado redshift
Meio interestelar
Linhas de emissão
Observações
Teses de mestrado - 2017
Departamento de Física
title_short On the hot interstellar medium of high-redshift galaxies
title_full On the hot interstellar medium of high-redshift galaxies
title_fullStr On the hot interstellar medium of high-redshift galaxies
title_full_unstemmed On the hot interstellar medium of high-redshift galaxies
title_sort On the hot interstellar medium of high-redshift galaxies
author Alegre, Lara Sofia Gorgulho
author_facet Alegre, Lara Sofia Gorgulho
author_role author
dc.contributor.none.fl_str_mv Sobral, David Ricardo Serrano Gonçalves
Repositório da Universidade de Lisboa
dc.contributor.author.fl_str_mv Alegre, Lara Sofia Gorgulho
dc.subject.por.fl_str_mv Galáxias
Evolução
Elevado redshift
Meio interestelar
Linhas de emissão
Observações
Teses de mestrado - 2017
Departamento de Física
topic Galáxias
Evolução
Elevado redshift
Meio interestelar
Linhas de emissão
Observações
Teses de mestrado - 2017
Departamento de Física
description Tese de mestrado, Física (Astrofísica e Cosmologia) Universidade de Lisboa, Faculdade de Ciências, 2017
publishDate 2017
dc.date.none.fl_str_mv 2017
2017
2017-01-01T00:00:00Z
2018-01-31T15:30:42Z
dc.type.status.fl_str_mv info:eu-repo/semantics/publishedVersion
dc.type.driver.fl_str_mv info:eu-repo/semantics/masterThesis
format masterThesis
status_str publishedVersion
dc.identifier.uri.fl_str_mv http://hdl.handle.net/10451/31293
TID:201870509
url http://hdl.handle.net/10451/31293
identifier_str_mv TID:201870509
dc.language.iso.fl_str_mv eng
language eng
dc.rights.driver.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.source.none.fl_str_mv reponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação
instacron:RCAAP
instname_str Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação
instacron_str RCAAP
institution RCAAP
reponame_str Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
collection Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
repository.name.fl_str_mv Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação
repository.mail.fl_str_mv
_version_ 1799134393081528320

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