CLASSY IV. Exploring UV Diagnostics of the Interstellar Medium in Local High-z Analogs at the Dawn of the JWST Era - Faculté des Sciences de Sorbonne Université Access content directly
Journal Articles The Astrophysical Journal Year : 2022

CLASSY IV. Exploring UV Diagnostics of the Interstellar Medium in Local High-z Analogs at the Dawn of the JWST Era

Matilde Mingozzi
  • Function : Author
Bethan L. James
  • Function : Author
Karla Z. Arellano-Córdova
  • Function : Author
Danielle A. Berg
  • Function : Author
Peter Senchyna
  • Function : Author
John Chisholm
  • Function : Author
Jarle Brinchmann
  • Function : Author
Alessandra Aloisi
  • Function : Author
Ricardo O. Amorín
  • Function : Author
Anna Feltre
  • Function : Author
Matthew Hayes
  • Function : Author
Timothy Heckman
  • Function : Author
Alaina Henry
  • Function : Author
Svea Hernandez
  • Function : Author
Nimisha Kumari
  • Function : Author
Claus Leitherer
  • Function : Author
Mario Llerena
  • Function : Author
Crystal L. Martin
  • Function : Author
Themiya Nanayakkara
  • Function : Author
Swara Ravindranath
  • Function : Author
Evan D. Skillman
  • Function : Author
Yuma Sugahara
  • Function : Author
Aida Wofford
  • Function : Author
Xinfeng Xu
  • Function : Author

Abstract

The Cosmic Origins Spectrograph (COS) Legacy Archive Spectroscopic SurveY (CLASSY) provides the first high-resolution spectral catalog of 45 local high-z analogs in the ultraviolet (UV; 1200-2000 Å) to investigate their stellar and gas properties. Here we present a toolkit of UV interstellar medium (ISM) diagnostics, analyzing the main emission lines of CLASSY spectra (N IV] λ λ1483,87, C IV λλ1548,51, He II λ1640, O III]λ λ1661,6, Si III] λλ1883,92, C III] λ1907,9). Specifically, our aim is to provide accurate diagnostics for the reddening E(B - V), electron density n e , electron temperature T e , metallicity 12+log(O/H), and ionization parameter log(U), taking the different ISM ionization zones into account. We calibrate our UV toolkit using well-known optical diagnostics, analyzing archival optical spectra for all CLASSY targets. We find that UV density diagnostics estimate n e values that are ~1-2 dex higher (e.g., n e (C III]λ λ1907,9) ~ 104 cm-3) than those inferred from their optical counterparts (e.g., n e ([S II]λ λ6717,31) ~ 102 cm-3; n e ([Ar IV]λ λ4714,41) ~ 103 cm-3). T e derived from the hybrid ratio [O III] λ1666/λ5007 proves to be reliable, implying differences in determining 12+log(O/H) compared to the optical counterpart O III] λ4363/[O III] λ5007 within ~ ±0.3 dex. We also investigate the relation between the stellar and gas E(B - V), finding consistent values at high specific star formation rates (sSFRs; $\mathrm{log}(\mathrm{sSFR})rsim -8$ yr-1), while at low sSFRs we confirmed an excess of dust attenuation in the gas. Finally, we investigate UV line ratios and equivalent widths to provide correlations with 12+log(O/H) and log(U), but note that there are degeneracies between the two. With this suite of UV-based diagnostics, we illustrate the pivotal role CLASSY plays in understanding the chemical and physical properties of high-z systems that JWST can observe in the rest-frame UV. *Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the Data Archive at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.
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hal-03974058 , version 1 (07-02-2023)

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Matilde Mingozzi, Bethan L. James, Karla Z. Arellano-Córdova, Danielle A. Berg, Peter Senchyna, et al.. CLASSY IV. Exploring UV Diagnostics of the Interstellar Medium in Local High-z Analogs at the Dawn of the JWST Era. The Astrophysical Journal, 2022, 939, ⟨10.3847/1538-4357/ac952c⟩. ⟨hal-03974058⟩
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