CLASSY. II. A Technical Overview of the COS Legacy Archive Spectroscopic Survey*

James, Bethan L.; Berg, Danielle A.; King, Teagan; Sahnow, David J.; Mingozzi, Matilde; Chisholm, John; Heckman, Timothy M.; Martin, Crystal L.; Stark, Dan; Aloisi, Alessandra; Amorín, R.; Arellano-Córdova, K. Z.; Bayliss, M.; Bordoloi, Rongmon; Brinchmann, Jarle; Charlot, S.; Chen, Zuyi; Chevallard, Jacopo; Clark, Ilyse; Erb, Dawn K.; Feltre, Anna; Hayes, Matthew; Henry, Alaina; Hernández, Svea; Jaskot, Anne; Kewley, Lisa J.; Kumari, Nimisha; Leitherer, Claus; Llerena, Mario; Maseda, Michael V.; Nanayakkara, Themiya; Ouchi, Masami; Plat, Adèle; Pogge, Richard W.; Ravindranath, Swara; Rigby, J. Keith; Scarlata, Claudia; Senchyna, Peter; Skillman, Evan D.; Steidel, Charles C.; Sugahara, Yuma; Wilkins, Stephen M.; Wofford, Aida; Xu, Xinfeng

doi:10.3847/1538-4365/ac8008

Cited by 21 publications

(17 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In this work we investigated UV and optical diagnostics of the ISM properties by exploiting the CLASSY survey presented by Berg et al (2022) and James et al (2022), which represents the first high-quality, high-resolution, and broad-wavelength-range (∼ 1200-2000 Å) FUV spectral database of 45 nearby (0.002 < z < 0.182) star-forming galaxies. Specifically we focused on the main UV emission lines visible in the COS spectra apart from Lyα (i.e., N IV] λλ 1483,87, C IV λλ1548,51, He II λ1640, O III]λλ 1661,6, Si III] λλ1883,92, C III] λλ1907,9), and combine them with emission lines comprised between [O II] λλ 3727,9 and [S III]λ9069 from optical spectroscopy of the same pointing.…”

Section: Discussionmentioning

confidence: 99%

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

Mingozzi

James

Arellano-Córdova

et al. 2022

ApJ

Self Cite

View full text Add to dashboard Cite

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; log ( sSFR ) ≳ − 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.

show abstract

Section: Discussionmentioning

confidence: 99%

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

Mingozzi

James

Arellano-Córdova

et al. 2022

ApJ

Self Cite

View full text Add to dashboard Cite

show abstract

“…A growing database of such spectra now exist especially from recent programs leveraging the sensitivity of HST/COS, targeting galaxies approaching the metallicities and stellar population ages likely to be encountered at high redshifts (see e.g. the COS Legacy Archive Spectroscopic Survey, or CLASSY; Berg et al 2022;James et al 2022).…”

Section: Insight From Local and Lower-redshift Samplesmentioning

confidence: 99%

GN-z11 in context: possible signatures of globular cluster precursors at redshift 10

Senchyna¹,

Plat²,

Stark³

et al. 2023

Preprint

View full text Add to dashboard Cite

The first JWST spectroscopy of the luminous galaxy GN-z11 simultaneously both established its redshift at z = 10.6 and revealed a rest-ultraviolet spectrum dominated by signatures of highly-ionized nitrogen, which has so far defied clear interpretation. Here we present a reappraisal of this spectrum in the context of both detailed nebular modeling and nearby metal-poor reference galaxies. The N IV] emission enables the first nebular density measurement in a star-forming galaxy at z > 10, and reveals evidence for extremely high densities n e 10 5 cm −3 . We definitively establish with a suite of photoionization models that regardless of ionization mechanism and accounting for depletion and this density enhancement, an ISM substantially enriched in nitrogen ([N/O] = +0.52) is required to reproduce the observed lines. A search of local UV databases confirms that nearby metal-poor galaxies power N IV] emission, but that this emission is uniformly associated with lower densities than implied in GN-z11. We compare to a unique nearby galaxy, Mrk 996, where a high concentration of Wolf-Rayet stars and their CNO-processed wind ejecta produce a UV spectrum remarkably similar to that of both GN-z11 and the Lyc-leaking super star cluster in the Sunburst Arc. Collating this evidence in the context of Galactic stellar abundances, we suggest that the peculiar nitrogenic features prominent in GN-z11 may be a unique signature of intense and densely clustered star formation in the evolutionary chain of the present-day globular clusters, consistent with in-situ early enrichment with nuclear-processed stellar ejecta on a massive scale. Combined with insight from local galaxies, these and future JWST data open a powerful new window onto the physical conditions of star formation and chemical enrichment at the highest redshifts.Keywords: High-redshift galaxies (734) -Blue compact dwarf galaxies ( 165) -Galaxy abundances (574) -Globular star clusters (656) * Carnegie Fellow large populations of globular clusters in the present-day Universe, whose typical metallicities ([Fe/H] ∼ −2.5-−1; Harris 1996) and inferred ages (uncertain, but ranging from ∼ 10 to 13 Gyr; Vandenberg et al. 1996; Brodie & Strader 2006) establish many as potentially forming at z 5 (e.g. Renzini 2017).Detailed study of globulars has also provided a mysterious clue about the character of the star formation episodes that produced them. Essentially all globulars differ from a single simple stellar population: and in particular, a substantial fraction of their stars (their 'enriched' or 'second' population) contain variations in light and heavy element abundances consistent with the yields of high-temperature nuclear burning (specifically, the CNO process and proton-capture chains, which produce abundance N, Na, and Al) that sharply distinguish them from field star populations (e.g. Osborn 1971; Smith

show abstract

“…All data were reduced locally using the COS data-reduction package CalCOS v.3.3.10,11 including spectra extraction and wavelength calibration. We refer readers to Berg et al (2022) and James et al (2022) for more details about these data reductions and spectral coaddition procedures. We also apply the same reductions to the LBA galaxies from Heckman et al (2015).…”

Section: Observations and Data Reductionsmentioning

confidence: 99%

“…In this paper, we aim to shed light on a method to measure n e , the radius at which these densities apply (r n ), M cl , and R cl from outflow absorption lines. We focus on 22 local starforming galaxies selected from the COS Legacy Archive Spectroscopy SurveY (CLASSY) atlas (Berg et al 2022;James et al 2022) and Heckman et al (2015). These galaxies have high signal-to-noise ratio (S/N) Hubble Space Telescope (HST)/Cosmic Origins Spectrograph (COS) spectra that cover their rest-frame UV bands.…”

Section: Introductionmentioning

confidence: 99%

CLASSY. VI. The Density, Structure, and Size of Absorption-line Outflows in Starburst Galaxies

Heckman

Henry

et al. 2023

ApJ

Self Cite

View full text Add to dashboard Cite

Galaxy formation and evolution are regulated by the feedback from galactic winds. Absorption lines provide the most widely available probe of winds. However, since most data only provide information integrated along the line of sight, they do not directly constrain the radial structure of the outflows. In this paper, we present a method to directly measure the gas electron density in outflows (n e ), which in turn yields estimates of outflow cloud properties (e.g., density, volume filling factor, and sizes/masses). We also estimate the distance (r n ) from the starburst at which the observed densities are found. We focus on 22 local star-forming galaxies primarily from the COS Legacy Archive Spectroscopic SurveY (CLASSY). In half of them, we detect absorption lines from fine-structure excited transitions of Si ii (i.e., Si ii*). We determine n e from relative column densities of Si ii and Si ii*, given Si ii* originates from collisional excitation by free electrons. We find that the derived n e correlates well with the galaxy’s star formation rate per unit area. From photoionization models or assuming the outflow is in pressure equilibrium with the wind fluid, we get r n ∼ 1–2r * or ∼5r *, respectively, where r * is the starburst radius. Based on comparisons to theoretical models of multiphase outflows, nearly all of the outflows have cloud sizes large enough for the clouds to survive their interaction with the hot wind fluid. Most of these measurements are the first ever for galactic winds detected in absorption lines and, thus, will provide important constraints for future models of galactic winds.

show abstract

CLASSY. II. A Technical Overview of the COS Legacy Archive Spectroscopic Survey*

Cited by 21 publications

References 28 publications

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

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

GN-z11 in context: possible signatures of globular cluster precursors at redshift 10

CLASSY. VI. The Density, Structure, and Size of Absorption-line Outflows in Starburst Galaxies

Contact Info

Product

Resources

About