CLASSY IV: Exploring UV diagnostics of the interstellar medium in local high-$z$ analogs at the dawn of the JWST era

Abstract

The COS Legacy Archive Spectroscopic SurveY (CLASSY) HST/COS treasury program provides the first high-resolution spectral catalogue of 45 local high-z analogues in the UV (1200-2000Å) to investigate their stellar and gas properties. We present a toolkit of UV interstellar medium (ISM) diagnostics, analyzing the main emission lines of CLASSY spectra (i.e., NIV]$\lambda \lambda$1483,87, CIV$\lambda \lambda$1548,51, HeII$\lambda$1640, OIII]$\lambda \lambda$1661,6, SiIII]$\lambda \lambda$1883,92, CIII]$\lambda \lambda$1907,9). Specifically, we focus our investigation on providing accurate diagnostics for reddening, electron density and temperature, gas-phase metallicity and ionization parameter, taking into account the different ionization zones of the ISM. We calibrate our UV toolkit using well-known optical diagnostics, analyzing archival optical spectra for all the CLASSY targets. We find that UV density diagnostics estimate ne values that are ~1-2 dex higher (e.g., ne(CIII]$\lambda \lambda$}1907,9)~10${}^4$cm${}^{-3}$) than those inferred from their optical counterparts (e.g., ne([SII]$\lambda \lambda$6717,31)~10${}^2$cm${}^{-3}$). Te derived from the hybrid ratio OIII]$\lambda$1666/[OIII]$\lambda$}5007 proves to be a reliable Te diagnostic, with differences in 12+log(O/H) within ~$\pm$0.3dex. We also investigate the relation between the stellar and gas E(B-V), finding consistent values at high specific star formation rates, while at low sSFR we confirm 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 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.

Accepted for publication on ApJ

References in corpus (48)

• Some Aspects of Measurement Error in Linear Regression of Astronomical Data
• Physical Properties of Wolf-Rayet Stars
• Cosmic Reionization and Early Star-Forming Galaxies: A Joint Analysis of New Constraints from Planck and Hubble Space Telescope
• PyNeb: a new tool for analyzing emission lines. I. Code description and validation of results
• Strong Nebular Line Ratios in the Spectra of z~2-3 Star-forming Galaxies: First Results from KBSS-MOSFIRE
• The Stellar, Gas and Dynamical Masses of Star-Forming Galaxies at z~2
• Understanding Galaxy Evolution through Emission Lines
• Modelling the nebular emission from primeval to present-day star-forming galaxies
• New fully empirical calibrations of strong-line metallicity indicators in star forming galaxies
• The chemical enrichment in the early Universe as probed by JWST via direct metallicity measurements at z~8
• The GLASS James Webb Space Telescope Early Release Science Program. I. Survey Design and Release Plans
• Galaxies with Wolf-Rayet signatures in the low-redshift Universe - A survey using the Sloan Digital Sky Survey
• Ultraviolet Emission Lines in Young Low Mass Galaxies at z~2: Physical Properties and Implications for Studies at z>7
• GOODS-HERSCHEL: star formation, dust attenuation and the FIR-radio correlation on the Main Sequence of star-forming galaxies up to z~4
• Spectroscopic detections of CIII]1909 at z~6-7: A new probe of early star forming galaxies and cosmic reionisation
• Ultraviolet spectra of extreme nearby star-forming regions --- approaching a local reference sample for JWST
• CHAOS I: Direct Chemical Abundances for HII Regions in NGC 628
• Rest-Frame Optical Spectra of Three Strongly Lensed Galaxies at z~2
• The Chemical Evolution of Carbon, Nitrogen, and Oxygen in Metal-Poor Dwarf Galaxies
• Modelling the Pan-Spectral Energy Distribution of Starburst Galaxies: II. Control of the \HII Region Parameters
• Gravitationally Lensed Galaxies at 2<z<3.5: Direct Abundance Measurements of Lya Emitters
• Evidence for a Hard Ionizing Spectrum from a z=6.11 Stellar Population
• The MOSDEF Survey: the Variation of the Dust Attenuation Curve with Metallicity
• The COS Legacy Archive Spectroscopy SurveY (CLASSY) Treasury Atlas
• Photoionization Models for the Semi-Forbidden C III] 1909 Emission in Star-Forming Galaxies
• MMT observations of new extremely metal-poor emission-line galaxies in the Sloan Digital Sky Survey
• The Galactic radial abundance gradients of C, N, O, Ne, S, Cl and Ar from deep spectra of H II regions
• Intense CIV and HeII Emission in z~0 Galaxies: Probing High-Energy Ionizing Photons
• A Semi-Analytical Line Transfer (SALT) model to interpret the spectra of galaxy outflows
• Directional Lya equivalent boosting I. Spherically symmetric distributions of clumps
• Exploring HeII$\lambda$1640 emission line properties at $z\sim 2-4$
• Strong Lyman continuum emitting galaxies show intense CIV 1550 emission
• The MUSE Hubble Ultra Deep Field Survey: IV. Global properties of C III] emitters
• Discrepancies between the [OIII] and [SIII] Temperatures in HII Regions
• Ultraviolet spectra of extreme nearby star-forming regions: evidence for an overabundance of very massive stars
• CLASSY II: A technical Overview of the COS Legacy Archive Spectroscopic SurveY
• Atomic Data Assessment with PyNeb
• The Semi-forbidden CIII]$\lambda$1909Å~ Emission in the Rest-Ultraviolet Spectra of Green Pea Galaxies
• Stars and gas in the most metal-poor galaxies I: COS and MUSE observations of SBS 0335-052E
• Direct Constraints on the Extremely Metal-Poor Massive Stars Underlying Nebular C IV Emission from Ultra-Deep HST/COS Ultraviolet Spectroscopy
• Using photo-ionisation models to derive carbon and oxygen gas-phase abundances in the rest UV
• Photoionized Herbig-Haro objects in the Orion Nebula through deep high-spectral resolution spectroscopy I: HH529II and III
• Recovery and analysis of rest-frame UV emission lines in 2052 galaxies observed with MUSE at $1.5<z<6.4$
• CLASSY V: The impact of aperture effects on the inferred nebular properties of local star-forming galaxies
• A Comparison of Rest-frame Ultraviolet and Optical Emission-Line Diagnostics in the Lensed Galaxy SDSS J1723+3411 at Redshift z=1.3293
• Keck Cosmic Web Imager Observations of He II Emission in I Zw 18
• Rest-frame UV and optical emission line diagnostics of ionised gas properties: a test case in a star-forming knot of a lensed galaxy at z~1.7
• Atomic data and the density structures of planetary nebulae

Cited by in corpus (26)

• JADES NIRSpec Spectroscopy of GN-z11: Lyman-$\alpha$ emission and possible enhanced nitrogen abundance in a $z=10.60$ luminous galaxy
• Nitrogen enhancements 440 Myr after the Big Bang: super-solar N/O, a tidal disruption event or a dense stellar cluster in GN-z11?
• Extreme N-emitters at high-redshift: signatures of supermassive stars and globular cluster or black hole formation in action?
• JADES: A large population of obscured, narrow line AGN at high redshift
• Nitrogen-enriched, highly-pressurized nebular clouds surrounding a super star cluster at cosmic noon
• The eventful life of a luminous galaxy at z = 14: metal enrichment, feedback, and low gas fraction?
• Early Results from GLASS-JWST. XXI: Rapid assembly of a galaxy at z=6.23 revealed by its C/O abundance
• Nebular emission from young stellar populations including binary stars
• Ionized gas kinematics and chemical abundances of low-mass star-forming galaxies at $z\sim 3$
• Insight into the Starburst Nature of Galaxy GN-z11 with JWST MIRI Spectroscopy
• Fast-rotating massive Population~III stars as possible sources of extreme N-enrichment in high-redshift galaxies
• Gas outflows in two recently quenched galaxies at z = 4 and 7
• HOMERUN a new approach to photoionization modelling. I -- reproducing observed emission lines with percent accuracy and obtaining accurate physical properties of the ionized gas
• The Dual Nature of GHZ9: Coexisting Active Galactic Nuclei and Star Formation Activity in a Remote X-ray Source at z = 10.145
• Accurate Oxygen Abundance of Interstellar Gas in Mrk 71 from Optical and Infrared Spectra
• The Ionizing Spectra of Extremely Metal-Poor O Stars: Constraints from the Only HII Region in Leo P
• Early Results from GLASS-JWST. XXV. Electron Density in the Interstellar Medium at $0.7\lesssim z\lesssim 9.3$ with NIRSpec High-resolution Spectroscopy
• New Ionization Models and the Shocking Nitrogen Excess at z > 5
• The impact of carbon and oxygen abundances on the metal-poor initial mass function
• Exploring the mysterious high-ionization source powering [Ne V] in high-z analog SBS0335-052 E with JWST/MIRI
• Nebular C IV 1550 Imaging of the Metal-Poor Starburst Mrk 71: Direct Evidence of Catastrophic Cooling
• Physical Origins of Outflowing Cold Clouds in Local Star-forming Dwarf Galaxies
• A constant upper luminosity limit of cool supergiant stars down to the extremely low metallicity of I Zw 18
• Unraveling the Lyman Continuum Emission of Ion3: Insights from HST multi-band imaging and X-Shooter spectroscopy
• Tracing nitrogen enrichment across cosmic time with JWST
• Shocks and complex chemodynamics in the metal-poor starburst galaxy CGCG 007-025 revealed through high-resolution echelle spectroscopy