Extremely metal-poor galaxies with HST/COS: laboratories for models of low-metallicity massive stars and high-redshift galaxies
Stark, Daniel P
AffiliationUniv Arizona, Steward Observ
MetadataShow full item record
PublisherOXFORD UNIV PRESS
CitationPeter Senchyna, Daniel P Stark, Jacopo Chevallard, Stéphane Charlot, Tucker Jones, Alba Vidal-García, Extremely metal-poor galaxies with HST/COS: laboratories for models of low-metallicity massive stars and high-redshift galaxies, Monthly Notices of the Royal Astronomical Society, Volume 488, Issue 3, September 2019, Pages 3492–3506, https://doi.org/10.1093/mnras/stz1907
Rights© 2019 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society.
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AbstractUltraviolet (UV) observations of local star-forming galaxies have begun to establish an empirical baseline for interpreting the rest-UV spectra of reionization-era galaxies. However, existing high-ionization emission line measurements al z > 6 (W-CIV,W-0 greater than or similar to 20 angstrom) are uniformly stronger than observed locally (W-CIV,W-0 less than or similar to 2 angstrom), likely due to the relatively high metallicities (Z/Z(circle dot) > 0.1) typically probed by UV surveys of nearby galaxies. We present new HST/COS spectra of six nearby (z < 0.01) extremely metal-poor galaxies (XMPs, Z/Z(circle dot) less than or similar to 0.1) targeted to address this limitation and provide constraints on the highly uncertain ionizing spectra powered by low-metallicity massive stars. Our data reveal a range of spectral features, including one of the most prominent nebular CIv doublets yet observed in local star-forming systems and strong He H. emission. Using all published UV observations of local XMPs to date, we find that nebular C IV emission is ubiquitous in very high specific star formation rate systems at low metallicity, but still find equivalent widths smaller than those measured in individual lensed systems at z > 6. Our moderate-resolution HST/COS data allow us to conduct an analysis of the stellar winds in a local nebular C iv emitter, which suggests that some of the tension with z > 6 data may be due to existing local samples not yet probing sufficiently high alpha/Fe abundance ratios. Our results indicate that C iv emission can play a crucial role in the IWST and ELT era by acting as an accessible signpost of very low metallicity (Z/Z(circle dot)) < 0.1) massive stars in assembling reionization-era systems.
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SponsorsNASANational Aeronautics & Space Administration (NASA) [NAS 5-26555, 14679]; W.M. Keck FoundationW.M. Keck Foundation; U.S. Department of EnergyUnited States Department of Energy (DOE); U.S. National Science FoundationNational Science Foundation (NSF); Ministry of Science and Education of SpainMinistry of Education and Science, Spain; Science and Technology FacilitiesCouncil of the United KingdomScience & Technology Facilities Council (STFC); Higher Education Funding Council for EnglandHigher Education Funding Council for England; National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign; Kavli Institute of Cosmological Physics at the University of Chicago; Center for Cosmology and Astro-Particle Physics at the Ohio State UniversityOhio State University; Mitchell Institute for Fundamental Physics and Astronomy at Texas AM University; Financiadora de Estudos e ProjetosCiencia Tecnologia e Inovacao (FINEP); Fundacao Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de JaneiroCarlos Chagas Filho Foundation for Research Support of the State of Rio de Janeiro (FAPERJ); Conselho Nacional de Desenvolvimento Cientifico e TecnologicoNational Council for Scientific and Technological Development (CNPq); Ministerio da Ciencia, Tecnologia e Inovacao; Deutsche ForschungsgemeinschaftGerman Research Foundation (DFG); Argonne National LaboratoryUnited States Department of Energy (DOE)University of Chicago; University of California at Santa Cruz; University of CambridgeUniversity of Cambridge; Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas-Madrid; University of ChicagoUniversity of Chicago; University College London; DES-Brazil Consortium; University of Edinburgh; Eidgenossische Technische Hochschule (ETH) ZurichETH Zurich; Fermi National Accelerator LaboratoryUnited States Department of Energy (DOE)University of Chicago; University of Illinois at Urbana-Champaign; Institut de Ciencies de l'Espai (IEEC/CSIC); Institut de Fisica d'Altes Energies; Lawrence Berkeley National LaboratoryUnited States Department of Energy (DOE); Ludwig-Maximilians Universitat Munchen; Excellence Cluster Universe; University of MichiganUniversity of Michigan System; Ohio State UniversityOhio State University; OzDES Membership Consortium; University of Pennsylvania; University of Portsmouth; SLAC National Accelerator Laboratory, Stanford University; University of Sussex; Texas AM University; National Science FoundationNational Science Foundation (NSF) [AST-1410155]; European Research Council (ERC)European Research Council (ERC) [321323-NEOGAL]; ERCEuropean Research Council (ERC) [742719-MIST]
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