ZFIRE: Measuring Electron Density with [O ii] as a Function of Environment at z = 1.62

Harshan, Anishya; Gupta, Anshu; Tran, Kim‐Vy H.; Alcorn, Leo Y.; Yuan, Tiantian; Kacprzak, Glenn G.; Nanayakkara, Themiya; Glazebrook, Karl; Kewley, Lisa J.; Labbé, Ivo; Papovich, C.

doi:10.3847/1538-4357/ab76cf

Cited by 20 publications

(9 citation statements)

References 94 publications

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“…Using the BPASS input ionizing spectrum, Cloudy predicts the rest-optical emission-line strengths for different combinations of physical properties. For this analysis, we set the N/O abundance ratio using equation (2) in Pilyugin et al (2012), use the Asplund et al (2009) [S II] abundance pattern, and assume that n e = 250 cm −3 , which is characteristic of z ∼ 2.3 galaxies (Sanders et al 2016;Strom et al 2017;Harshan et al 2020). This value for n e is slightly lower than the median values of our high and low samples; however, it is within the uncertainties of the low population and not significantly less than the lower limit of the high population median.…”

Section: Modeling Methodologymentioning

confidence: 99%

The MOSDEF Survey: A Comprehensive Analysis of the Rest-optical Emission-line Properties of $z\sim 2.3$ Star-forming Galaxies

Runco,

Shapley,

Sanders

et al. 2020

Preprint

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We analyze the rest-optical emission-line spectra of z ∼ 2.3 star-forming galaxies in the complete MOSFIRE Deep Evolution Field (MOSDEF) survey. In investigating the origin of the well-known offset between the sequences of high-redshift and local galaxies in the [O III]λ5008/Hβ vs. [N II]λ6585/Hα ("[N II] BPT") diagram, we define two populations of z ∼ 2.3 MOSDEF galaxies. These include the high population that is offset towards higher [O III]λ5008/Hβ and/or [N II]λ6585/Hα with respect to the local SDSS sequence and the low population that overlaps the SDSS sequence. These two groups are also segregated within the [O III]λ5008/Hβ vs. [S II]λλ6718,6733/Hα and the [O III]λλ4960,5008/[O II]λλ3727,3730 (O 32 ) vs. ([O III]λλ4960,5008+[O II]λλ3727,3730)/Hβ (R 23 ) diagram, which suggests qualita-tively that star-forming regions in the more offset galaxies are characterized by harder ionizing spectra at fixed nebular oxygen abundance. We also investigate many galaxy properties of the split sample and find that the high sample is on average smaller in size and less massive, but has higher specific star-formation rate and star-formation-rate surface density values and is slightly younger compared to the low population. From Cloudy+BPASS photoionization models, we estimate that the high population has a lower stellar metallicity (i.e., harder ionizing spectrum) but slightly higher nebular metallicity and higher ionization parameter compared to the low population. While the high population is more α-enhanced (i.e., higher α/Fe) than the low population, both samples are significantly more α-enhanced compared to local star-forming galaxies with similar rest-optical line ratios. These differences must be accounted for in all high-redshift star-forming galaxies -not only those "offset" from local excitation sequences.

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Section: Modeling Methodologymentioning

confidence: 99%

The MOSDEF Survey: A Comprehensive Analysis of the Rest-optical Emission-line Properties of $z\sim 2.3$ Star-forming Galaxies

Runco,

Shapley,

Sanders

et al. 2020

Preprint

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“…The ranges of stellar mass, SFR, and metallicity are shown in Figure 1. To better sample the higher nebular densities observed for z > 1 galaxies (e.g., Shirazi et al 2014;Sanders et al 2016;Kaasinen et al 2017;Harshan et al 2020) and directly study the effect of electron density on rest-FUV galaxy properties, we mined the Sloan Digital Sky Survey Data Release 12 37 (SDSS-III DR12; Eisenstein et al 2011;Alam et al 2015) and existing literature in order to unearth additional targets with [S II] λλ6717,6731 densities of n e > 400 cm −3 . Although such targets are extremely rare at z ∼ 0, we were able to compile a sample of 10 galaxies in our socalled "high-density sample" that met criteria (1)-(4).…”

Section: Sample Selectionmentioning

confidence: 99%

The COS Legacy Archive Spectroscopy Survey (CLASSY) Treasury Atlas*

Berg¹,

James²,

King³

et al. 2022

ApJS

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Far-ultraviolet (FUV; ∼1200–2000 Å) spectra are fundamental to our understanding of star-forming galaxies, providing a unique window on massive stellar populations, chemical evolution, feedback processes, and reionization. The launch of the James Webb Space Telescope will soon usher in a new era, pushing the UV spectroscopic frontier to higher redshifts than ever before; however, its success hinges on a comprehensive understanding of the massive star populations and gas conditions that power the observed UV spectral features. This requires a level of detail that is only possible with a combination of ample wavelength coverage, signal-to-noise, spectral-resolution, and sample diversity that has not yet been achieved by any FUV spectral database. We present the Cosmic Origins Spectrograph Legacy Spectroscopic Survey (CLASSY) treasury and its first high-level science product, the CLASSY atlas. CLASSY builds on the Hubble Space Telescope (HST) archive to construct the first high-quality (S/N1500 Å ≳ 5/resel), high-resolution (R ∼ 15,000) FUV spectral database of 45 nearby (0.002 < z < 0.182) star-forming galaxies. The CLASSY atlas, available to the public via the CLASSY website, is the result of optimally extracting and coadding 170 archival+new spectra from 312 orbits of HST observations. The CLASSY sample covers a broad range of properties including stellar mass (6.2 < log M ⋆(M ⊙) < 10.1), star formation rate (−2.0 < log SFR (M ⊙ yr−1) < +1.6), direct gas-phase metallicity (7.0 < 12+log(O/H) < 8.8), ionization (0.5 < O32 < 38.0), reddening (0.02 < E(B − V) < 0.67), and nebular density (10 < n e (cm−3) < 1120). CLASSY is biased to UV-bright star-forming galaxies, resulting in a sample that is consistent with the z ∼ 0 mass–metallicity relationship, but is offset to higher star formation rates by roughly 2 dex, similar to z ≳ 2 galaxies. This unique set of properties makes the CLASSY atlas the benchmark training set for star-forming galaxies across cosmic time.

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“…The ranges of stellar mass, SFR, and metallicity are shown in Figure 2. To better sample the higher nebular densities observed for z > 1 galaxies (e.g., Shirazi et al 2014;Sanders et al 2016;Kaasinen et al 2017;Harshan et al 2020) and directly study the effect of electron density on rest-FUV galaxy properties, we mined the Sloan Digital Sky Survey Data Release 12 2 (SDSS-III DR12; Eisenstein et al 2011;Alam et al 2015) and existing literature in order to unearth additional targets with [S II] λλ6717,6731 densities of n e > 400 cm −3 . Although such targets are extremely rare at z ∼ 0, we were able to compile a sample of 10 galaxies in our so-called "high-density sample" that met criteria 1-4.…”

Section: Sample Selectionmentioning

confidence: 99%

The COS Legacy Archive Spectroscopy SurveY (CLASSY) Treasury Atlas

Berg,

James,

King

et al. 2022

Preprint

Self Cite

View full text Add to dashboard Cite

Far-ultraviolet (FUV;∼ 1200 − 2000Å) spectra are fundamental to our understanding of star-forming galaxies, providing a unique window on massive stellar populations, chemical evolution, feedback processes, and reionization. The launch of JWST will soon usher in a new era, pushing the UV spectroscopic frontier to higher redshifts than ever before, however, its success hinges on a comprehensive understanding of the massive star populations and gas conditions that power the observed UV spectral features. This requires a level of detail that is only possible with a combination of ample wavelength coverage, signal-to-noise, spectral-resolution, and sample diversity that has not yet been achieved by any FUV spectral database.We present the COS Legacy Spectroscopic SurveY (CLASSY) treasury and its first high level science product, the CLASSY atlas. CLASSY builds on the HST archive to construct the first high-quality (S/N 1500 5/resel), high-resolution (R ∼ 15, 000) FUV spectral database of 45 nearby (0.002 < z < 0.182) star-forming galaxies. The CLASSY atlas, available to the public via the CLASSY website, is the result of optimally extracting and coadding 170 archival+new spectra from 312 orbits of HST observations.The CLASSY sample covers a broad range of properties including stellar mass (6.2 < log M (M ) < 10.1), star formation rate (−2.0 < log SFR (M yr −1 ) < +1.6), direct gas-phase metallicity (7.0 < 12+log(O/H) < 8.8), ionization (0.5 < O 32 < 38.0), reddening (0.02 < E(B-V) < 0.67), and nebular density (10 < n e (cm −3 ) < 1120). CLASSY is biased to UV-bright star-forming galaxies, resulting in a sample that is consistent with z ∼ 0 massmetallicity relationship, but is offset to higher SFRs by roughly 2 dex, similar to z 2 galaxies. This unique set of properties makes the CLASSY atlas the benchmark training set for star-forming galaxies across cosmic time.

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ZFIRE: Measuring Electron Density with [O ii] as a Function of Environment at z = 1.62

Cited by 20 publications

References 94 publications

The MOSDEF Survey: A Comprehensive Analysis of the Rest-optical Emission-line Properties of $z\sim 2.3$ Star-forming Galaxies

The MOSDEF Survey: A Comprehensive Analysis of the Rest-optical Emission-line Properties of $z\sim 2.3$ Star-forming Galaxies

The COS Legacy Archive Spectroscopy Survey (CLASSY) Treasury Atlas*

The COS Legacy Archive Spectroscopy SurveY (CLASSY) Treasury Atlas

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