The MOSDEF survey: [SIII] as a new probe of evolving interstellar medium conditions

Ryan L. Sanders; Tucker Jones; Alice E. Shapley; Naveen A. Reddy; Mariska Kriek; Alison L. Coil; Brian Siana; Bahram Mobasher; Irene Shivaei; Sedona H. Price; William R. Freeman; Mojegan Azadi; Gene C.K. Leung; Tara Fetherolf; Tom O. Zick; Laura de Groot; Guillermo Barro; Francesca M. Fornasini

doi:10.3847/2041-8213/ab5d40

The MOSDEF survey: [SIII] as a new probe of evolving interstellar medium conditions

Ryan L. Sanders, Tucker Jones, Alice E. Shapley, Naveen A. Reddy, Mariska Kriek, Alison L. Coil, Brian Siana, Bahram Mobasher, Irene Shivaei, Sedona H. Price, William R. Freeman, Mojegan Azadi, Gene C.K. Leung, Tara Fetherolf, Tom O. Zick, Laura de Groot, Guillermo Barro, Francesca M. Fornasini

Physics And Astronomy

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Abstract

We present measurements of [S III]λλ9069,9531 for a sample of z ∼ 1.5 star-forming galaxies, the first representative sample with measurements of these lines at z ≿ 0.1. We employ the line ratio S₃₂ ≡ [S III]λλ9069,9531/[S II]λλ6716,6731 as a novel probe of evolving interstellar medium (ISM) conditions. Since this ratio includes the low-ionization line [S II], it is crucial that the effects of diffuse ionized gas (DIG) on emission-line ratios be accounted for in z ∼ 0 galaxy spectra, or else that comparisons be made to samples of local H II regions in which DIG emission is not present. We find that S₃₂ decreases with increasing stellar mass at both z ∼ 1.5 and z ∼ 0, but with a shallow slope suggesting S₃₂ has a weak dependence on metallicity, in contrast with [O III]/[O II] that displays a strong metallicity dependence. As a result, S₃₂ only mildly evolves with redshift at fixed stellar mass. The z ∼ 1.5 sample is systematically offset toward lower S₃₂ and higher [S II]/Hα at fixed [O III]/Hβ relative to z = 0 H II regions. We find that such trends can be explained by a scenario in which the ionizing spectrum is harder at fixed O/H with increasing redshift, but are inconsistent with an increase in ionization parameter at fixed O/H. This analysis demonstrates the advantages of expanding beyond the strongest rest-optical lines for evolutionary studies, and the particular utility of [S III] for characterizing evolving ISM conditions and stellar compositions. These measurements provide a basis for estimating [S III] line strengths for high-redshift galaxies, a line that the James Webb Space Telescope will measure out to z ∼ 5.5.

Original language	English
Journal	Astrophysical Journal Letters
Volume	888
Issue number	1
DOIs	https://doi.org/10.3847/2041-8213/ab5d40
State	Published - Jan 1 2020

Bibliographical note

Funding Information:
We acknowledge support from NSF AAG grants AST-1312780, 1312547, 1312764, and 1313171, grants AR-13907 and GO-15077 provided by NASA through the Space Telescope Science Institute, and grant NNX16AF54G from the NASA ADAP program. We also acknowledge a NASA contract supporting the WFIRST Extragalactic Potential Observations (EXPO) Science Investigation Team (15-WFIRST15-0004), administered by GSFC. We wish to extend special thanks to those of Hawaiʻian ancestry on whose sacred mountain we are privileged to be guests. Without their generous hospitality, the work presented herein would not have been possible.

Funding Information:
Based on data obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA, and was made possible by the generous financial support of the W.M. Keck Foundation. We acknowledge support from NSF AAG grants AST-1312780, 1312547, 1312764, and 1313171, grants AR-13907 and GO-15077 provided by NASA through the Space Telescope Science Institute, and grant NNX16AF54G from the NASA ADAP program. We also acknowledge a NASA contract supporting the WFIRST Extragalactic Potential Observations (EXPO) Science Investigation Team (15-WFIRST15-0004), administered by GSFC. We wish to extend special thanks to those of Hawai'ian ancestry on whose sacred mountain we are privileged to be guests. Without their generous hospitality, the work presented herein would not have been possible.

Publisher Copyright:
© 2019. The American Astronomical Society. All rights reserved.

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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10.3847/2041-8213/ab5d40

Cite this

Sanders, R. L., Jones, T., Shapley, A. E., Reddy, N. A., Kriek, M., Coil, A. L., Siana, B., Mobasher, B., Shivaei, I., Price, S. H., Freeman, W. R., Azadi, M., Leung, G. C. K., Fetherolf, T., Zick, T. O., de Groot, L., Barro, G., & Fornasini, F. M. (2020). The MOSDEF survey: [SIII] as a new probe of evolving interstellar medium conditions. Astrophysical Journal Letters, 888(1). https://doi.org/10.3847/2041-8213/ab5d40

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title = "The MOSDEF survey: [SIII] as a new probe of evolving interstellar medium conditions",

abstract = "We present measurements of [S III]λλ9069,9531 for a sample of z ∼ 1.5 star-forming galaxies, the first representative sample with measurements of these lines at z ≿ 0.1. We employ the line ratio S32 ≡ [S III]λλ9069,9531/[S II]λλ6716,6731 as a novel probe of evolving interstellar medium (ISM) conditions. Since this ratio includes the low-ionization line [S II], it is crucial that the effects of diffuse ionized gas (DIG) on emission-line ratios be accounted for in z ∼ 0 galaxy spectra, or else that comparisons be made to samples of local H II regions in which DIG emission is not present. We find that S32 decreases with increasing stellar mass at both z ∼ 1.5 and z ∼ 0, but with a shallow slope suggesting S32 has a weak dependence on metallicity, in contrast with [O III]/[O II] that displays a strong metallicity dependence. As a result, S32 only mildly evolves with redshift at fixed stellar mass. The z ∼ 1.5 sample is systematically offset toward lower S32 and higher [S II]/Hα at fixed [O III]/Hβ relative to z = 0 H II regions. We find that such trends can be explained by a scenario in which the ionizing spectrum is harder at fixed O/H with increasing redshift, but are inconsistent with an increase in ionization parameter at fixed O/H. This analysis demonstrates the advantages of expanding beyond the strongest rest-optical lines for evolutionary studies, and the particular utility of [S III] for characterizing evolving ISM conditions and stellar compositions. These measurements provide a basis for estimating [S III] line strengths for high-redshift galaxies, a line that the James Webb Space Telescope will measure out to z ∼ 5.5.",

author = "Sanders, {Ryan L.} and Tucker Jones and Shapley, {Alice E.} and Reddy, {Naveen A.} and Mariska Kriek and Coil, {Alison L.} and Brian Siana and Bahram Mobasher and Irene Shivaei and Price, {Sedona H.} and Freeman, {William R.} and Mojegan Azadi and Leung, {Gene C.K.} and Tara Fetherolf and Zick, {Tom O.} and {de Groot}, Laura and Guillermo Barro and Fornasini, {Francesca M.}",

note = "Funding Information: We acknowledge support from NSF AAG grants AST-1312780, 1312547, 1312764, and 1313171, grants AR-13907 and GO-15077 provided by NASA through the Space Telescope Science Institute, and grant NNX16AF54G from the NASA ADAP program. We also acknowledge a NASA contract supporting the WFIRST Extragalactic Potential Observations (EXPO) Science Investigation Team (15-WFIRST15-0004), administered by GSFC. We wish to extend special thanks to those of Hawaiʻian ancestry on whose sacred mountain we are privileged to be guests. Without their generous hospitality, the work presented herein would not have been possible. Funding Information: Based on data obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA, and was made possible by the generous financial support of the W.M. Keck Foundation. We acknowledge support from NSF AAG grants AST-1312780, 1312547, 1312764, and 1313171, grants AR-13907 and GO-15077 provided by NASA through the Space Telescope Science Institute, and grant NNX16AF54G from the NASA ADAP program. We also acknowledge a NASA contract supporting the WFIRST Extragalactic Potential Observations (EXPO) Science Investigation Team (15-WFIRST15-0004), administered by GSFC. We wish to extend special thanks to those of Hawai'ian ancestry on whose sacred mountain we are privileged to be guests. Without their generous hospitality, the work presented herein would not have been possible. Publisher Copyright: {\textcopyright} 2019. The American Astronomical Society. All rights reserved.",

year = "2020",

month = jan,

day = "1",

doi = "10.3847/2041-8213/ab5d40",

language = "English",

volume = "888",

number = "1",

}

Sanders, RL, Jones, T, Shapley, AE, Reddy, NA, Kriek, M, Coil, AL, Siana, B, Mobasher, B, Shivaei, I, Price, SH, Freeman, WR, Azadi, M, Leung, GCK, Fetherolf, T, Zick, TO, de Groot, L, Barro, G & Fornasini, FM 2020, 'The MOSDEF survey: [SIII] as a new probe of evolving interstellar medium conditions', Astrophysical Journal Letters, vol. 888, no. 1. https://doi.org/10.3847/2041-8213/ab5d40

TY - JOUR

T1 - The MOSDEF survey

T2 - [SIII] as a new probe of evolving interstellar medium conditions

AU - Sanders, Ryan L.

AU - Jones, Tucker

AU - Shapley, Alice E.

AU - Reddy, Naveen A.

AU - Kriek, Mariska

AU - Coil, Alison L.

AU - Siana, Brian

AU - Mobasher, Bahram

AU - Shivaei, Irene

AU - Price, Sedona H.

AU - Freeman, William R.

AU - Azadi, Mojegan

AU - Leung, Gene C.K.

AU - Fetherolf, Tara

AU - Zick, Tom O.

AU - de Groot, Laura

AU - Barro, Guillermo

AU - Fornasini, Francesca M.

N1 - Funding Information: We acknowledge support from NSF AAG grants AST-1312780, 1312547, 1312764, and 1313171, grants AR-13907 and GO-15077 provided by NASA through the Space Telescope Science Institute, and grant NNX16AF54G from the NASA ADAP program. We also acknowledge a NASA contract supporting the WFIRST Extragalactic Potential Observations (EXPO) Science Investigation Team (15-WFIRST15-0004), administered by GSFC. We wish to extend special thanks to those of Hawaiʻian ancestry on whose sacred mountain we are privileged to be guests. Without their generous hospitality, the work presented herein would not have been possible. Funding Information: Based on data obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA, and was made possible by the generous financial support of the W.M. Keck Foundation. We acknowledge support from NSF AAG grants AST-1312780, 1312547, 1312764, and 1313171, grants AR-13907 and GO-15077 provided by NASA through the Space Telescope Science Institute, and grant NNX16AF54G from the NASA ADAP program. We also acknowledge a NASA contract supporting the WFIRST Extragalactic Potential Observations (EXPO) Science Investigation Team (15-WFIRST15-0004), administered by GSFC. We wish to extend special thanks to those of Hawai'ian ancestry on whose sacred mountain we are privileged to be guests. Without their generous hospitality, the work presented herein would not have been possible. Publisher Copyright: © 2019. The American Astronomical Society. All rights reserved.

PY - 2020/1/1

Y1 - 2020/1/1

N2 - We present measurements of [S III]λλ9069,9531 for a sample of z ∼ 1.5 star-forming galaxies, the first representative sample with measurements of these lines at z ≿ 0.1. We employ the line ratio S32 ≡ [S III]λλ9069,9531/[S II]λλ6716,6731 as a novel probe of evolving interstellar medium (ISM) conditions. Since this ratio includes the low-ionization line [S II], it is crucial that the effects of diffuse ionized gas (DIG) on emission-line ratios be accounted for in z ∼ 0 galaxy spectra, or else that comparisons be made to samples of local H II regions in which DIG emission is not present. We find that S32 decreases with increasing stellar mass at both z ∼ 1.5 and z ∼ 0, but with a shallow slope suggesting S32 has a weak dependence on metallicity, in contrast with [O III]/[O II] that displays a strong metallicity dependence. As a result, S32 only mildly evolves with redshift at fixed stellar mass. The z ∼ 1.5 sample is systematically offset toward lower S32 and higher [S II]/Hα at fixed [O III]/Hβ relative to z = 0 H II regions. We find that such trends can be explained by a scenario in which the ionizing spectrum is harder at fixed O/H with increasing redshift, but are inconsistent with an increase in ionization parameter at fixed O/H. This analysis demonstrates the advantages of expanding beyond the strongest rest-optical lines for evolutionary studies, and the particular utility of [S III] for characterizing evolving ISM conditions and stellar compositions. These measurements provide a basis for estimating [S III] line strengths for high-redshift galaxies, a line that the James Webb Space Telescope will measure out to z ∼ 5.5.

AB - We present measurements of [S III]λλ9069,9531 for a sample of z ∼ 1.5 star-forming galaxies, the first representative sample with measurements of these lines at z ≿ 0.1. We employ the line ratio S32 ≡ [S III]λλ9069,9531/[S II]λλ6716,6731 as a novel probe of evolving interstellar medium (ISM) conditions. Since this ratio includes the low-ionization line [S II], it is crucial that the effects of diffuse ionized gas (DIG) on emission-line ratios be accounted for in z ∼ 0 galaxy spectra, or else that comparisons be made to samples of local H II regions in which DIG emission is not present. We find that S32 decreases with increasing stellar mass at both z ∼ 1.5 and z ∼ 0, but with a shallow slope suggesting S32 has a weak dependence on metallicity, in contrast with [O III]/[O II] that displays a strong metallicity dependence. As a result, S32 only mildly evolves with redshift at fixed stellar mass. The z ∼ 1.5 sample is systematically offset toward lower S32 and higher [S II]/Hα at fixed [O III]/Hβ relative to z = 0 H II regions. We find that such trends can be explained by a scenario in which the ionizing spectrum is harder at fixed O/H with increasing redshift, but are inconsistent with an increase in ionization parameter at fixed O/H. This analysis demonstrates the advantages of expanding beyond the strongest rest-optical lines for evolutionary studies, and the particular utility of [S III] for characterizing evolving ISM conditions and stellar compositions. These measurements provide a basis for estimating [S III] line strengths for high-redshift galaxies, a line that the James Webb Space Telescope will measure out to z ∼ 5.5.

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U2 - 10.3847/2041-8213/ab5d40

DO - 10.3847/2041-8213/ab5d40

M3 - Article

AN - SCOPUS:85079829466

SN - 2041-8205

VL - 888

JO - Astrophysical Journal Letters

JF - Astrophysical Journal Letters

IS - 1

ER -

The MOSDEF survey: [SIII] as a new probe of evolving interstellar medium conditions

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Bibliographical note

ASJC Scopus subject areas

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