TY - JOUR
T1 - SGAME Simulations of the [CII], [OI], and [OIII] Line Emission from Star-forming Galaxies at z≲ 6
AU - Olsen, Karen
AU - Greve, Thomas R.
AU - Narayanan, Desika
AU - Thompson, Robert
AU - Davé, Romeel
AU - Rios, Luis Niebla
AU - Stawinski, Stephanie
N1 - Publisher Copyright:
© 2017. The American Astronomical Society. All rights reserved.
PY - 2017/9/10
Y1 - 2017/9/10
N2 - Of the almost 40 star-forming galaxies at z ≥ 5 (not counting quasi-stellar objects) observed in [CII] to date, nearly half are either very faint in [CII] or not detected at all, and fall well below expectations based on locally derived relations between star formation rate and [CII] luminosity. This has raised questions as to how reliable [CII] is as a tracer of star formation activity at these epochs and how factors such as metallicity might affect the [CII] emission. Combining cosmological zoom simulations of galaxies with SGAME (SImulator of GAlaxy Millimeter/ submillimeter Emission), we modeled the multiphased interstellar medium (ISM) and its emission in [CII] , as well as in [OI] and [OIII], from 30 main-sequence galaxies at z ≲6 with star formation rates ∼323 M· yr-1, stellar masses ∼ 0.7 8 109 M·, and metallicities ∼ 0.1 0.4 Z?. The simulations are able to reproduce the aforementioned [CII] faintness of some normal star-forming galaxy sources at z 5. In terms of [OI] and [OIII], very few observations are available at z 5, but our simulations match two of the three existing z 5 detections of [OIII] and are furthermore roughly consistent with the [OI] and [OIII] luminosity relations with star formation rate observed for local starburst galaxies. We find that the [CII] emission is dominated by the diffuse ionized gas phase and molecular clouds, which on average contribute ∼66% and ∼27%, respectively. The molecular gas, which constitutes only ∼10% of the total gas mass, is thus a more efficient emitter of [CII] than the ionized gas, which makes up ∼85% of the total gas mass. A principal component analysis shows that the [CII] luminosity correlates with the star formation activity of a galaxy as well as its average metallicity. The low metallicities of our simulations together with their low molecular gas mass fractions can account for their [CII] faintness, and we suggest that these factors may also be responsible for the [CII] -faint normal galaxies observed at these early epochs.
AB - Of the almost 40 star-forming galaxies at z ≥ 5 (not counting quasi-stellar objects) observed in [CII] to date, nearly half are either very faint in [CII] or not detected at all, and fall well below expectations based on locally derived relations between star formation rate and [CII] luminosity. This has raised questions as to how reliable [CII] is as a tracer of star formation activity at these epochs and how factors such as metallicity might affect the [CII] emission. Combining cosmological zoom simulations of galaxies with SGAME (SImulator of GAlaxy Millimeter/ submillimeter Emission), we modeled the multiphased interstellar medium (ISM) and its emission in [CII] , as well as in [OI] and [OIII], from 30 main-sequence galaxies at z ≲6 with star formation rates ∼323 M· yr-1, stellar masses ∼ 0.7 8 109 M·, and metallicities ∼ 0.1 0.4 Z?. The simulations are able to reproduce the aforementioned [CII] faintness of some normal star-forming galaxy sources at z 5. In terms of [OI] and [OIII], very few observations are available at z 5, but our simulations match two of the three existing z 5 detections of [OIII] and are furthermore roughly consistent with the [OI] and [OIII] luminosity relations with star formation rate observed for local starburst galaxies. We find that the [CII] emission is dominated by the diffuse ionized gas phase and molecular clouds, which on average contribute ∼66% and ∼27%, respectively. The molecular gas, which constitutes only ∼10% of the total gas mass, is thus a more efficient emitter of [CII] than the ionized gas, which makes up ∼85% of the total gas mass. A principal component analysis shows that the [CII] luminosity correlates with the star formation activity of a galaxy as well as its average metallicity. The low metallicities of our simulations together with their low molecular gas mass fractions can account for their [CII] faintness, and we suggest that these factors may also be responsible for the [CII] -faint normal galaxies observed at these early epochs.
KW - cosmology: theory
KW - galaxies: ISM
KW - galaxies: high-redshift
KW - line: formation
KW - methods: numerical
KW - submillimeter: ISM
UR - http://www.scopus.com/inward/record.url?scp=85029475573&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85029475573&partnerID=8YFLogxK
U2 - 10.3847/1538-4357/aa86b4
DO - 10.3847/1538-4357/aa86b4
M3 - Article
AN - SCOPUS:85029475573
SN - 0004-637X
VL - 846
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2
M1 - 105
ER -