Extremely metal-poor galaxies with HST/COS: laboratories for models of low-metallicity massive stars and high-redshift galaxies
Publisher
OXFORD UNIV PRESSCitation
Peter 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/stz1907Rights
© 2019 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society.Collection Information
This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.Abstract
Ultraviolet (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.ISSN
0035-8711Version
Final published versionSponsors
NASANational 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]Scopus Count
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