Tracing Molecular Gas Mass in z similar or equal to 6 Galaxies with [C II]
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Tracing Molecular Gas Mass in z similar or equal to 6 Galaxies with [C II]. / Vizgan, D.; Greve, T. R.; Olsen, K. P.; Zanella, A.; Narayanan, D.; Dave, R.; Magdis, G. E.; Popping, G.; Valentino, F.; Heintz, K. E.
I: Astrophysical Journal, Bind 929, Nr. 1, 92, 01.04.2022.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - Tracing Molecular Gas Mass in z similar or equal to 6 Galaxies with [C II]
AU - Vizgan, D.
AU - Greve, T. R.
AU - Olsen, K. P.
AU - Zanella, A.
AU - Narayanan, D.
AU - Dave, R.
AU - Magdis, G. E.
AU - Popping, G.
AU - Valentino, F.
AU - Heintz, K. E.
PY - 2022/4/1
Y1 - 2022/4/1
N2 - We investigate the fine-structure [C II] line at 158 mu m as a molecular gas tracer by analyzing the relationship between molecular gas mass (M-mol) and [C II] line luminosity (L-[C (II)]) in 11,125 z similar or equal to 6 star-forming, main-sequence galaxies from the SIMBA simulations, with line emission modeled by the Simulator of Galaxy Millimeter/Submillimeter Emission. Though most (similar to 50%-100%) of the gas mass in our simulations is ionized, the bulk (>50%) of the [C II] emission comes from the molecular phase. We find a sublinear (slope 0.78 +/- 0.01) log L-[C II]-log M-mol relation, in contrast with the linear relation derived from observational samples of more massive, metal-rich galaxies at z similar or equal to 6. We derive a median [C II]-to-M-mol conversion factor of alpha([C )(II]) similar or equal to 18 M-circle dot/L-circle dot. This is lower than the average value of similar or equal to 30 M-circle dot/L-circle dot derived from observations, which we attribute to lower gas-phase metallicities in our simulations. Thus, a lower, luminosity-dependent conversion factor must be applied when inferring molecular gas masses from [C II] observations of low-mass galaxies. For our simulations, [C is a better tracer of the molecular gas than CO J= 1-0, especially at the lowest metallicities, where much of the gas is CO-dark. We find that L-[C (II)] is more tightly correlated with M-mol than with star formation rate (SFR), and both the log L-[C II] - log M-mol and log L-[C II]-log SFR relations arise from the Kennicutt-Schmidt relation. Our findings suggest that L-[C II] is a promising tracer of the molecular gas at the earliest cosmic epochs.
AB - We investigate the fine-structure [C II] line at 158 mu m as a molecular gas tracer by analyzing the relationship between molecular gas mass (M-mol) and [C II] line luminosity (L-[C (II)]) in 11,125 z similar or equal to 6 star-forming, main-sequence galaxies from the SIMBA simulations, with line emission modeled by the Simulator of Galaxy Millimeter/Submillimeter Emission. Though most (similar to 50%-100%) of the gas mass in our simulations is ionized, the bulk (>50%) of the [C II] emission comes from the molecular phase. We find a sublinear (slope 0.78 +/- 0.01) log L-[C II]-log M-mol relation, in contrast with the linear relation derived from observational samples of more massive, metal-rich galaxies at z similar or equal to 6. We derive a median [C II]-to-M-mol conversion factor of alpha([C )(II]) similar or equal to 18 M-circle dot/L-circle dot. This is lower than the average value of similar or equal to 30 M-circle dot/L-circle dot derived from observations, which we attribute to lower gas-phase metallicities in our simulations. Thus, a lower, luminosity-dependent conversion factor must be applied when inferring molecular gas masses from [C II] observations of low-mass galaxies. For our simulations, [C is a better tracer of the molecular gas than CO J= 1-0, especially at the lowest metallicities, where much of the gas is CO-dark. We find that L-[C (II)] is more tightly correlated with M-mol than with star formation rate (SFR), and both the log L-[C II] - log M-mol and log L-[C II]-log SFR relations arise from the Kennicutt-Schmidt relation. Our findings suggest that L-[C II] is a promising tracer of the molecular gas at the earliest cosmic epochs.
KW - STAR-FORMING GALAXIES
KW - CO-TO-H-2 CONVERSION FACTOR
KW - SUBMILLIMETER GALAXIES
KW - INTERSTELLAR-MEDIUM
KW - ATOMIC CARBON
KW - EMISSION
KW - ACCURATE
KW - MODEL
KW - EVOLUTION
KW - RELEASE
U2 - 10.3847/1538-4357/ac5cba
DO - 10.3847/1538-4357/ac5cba
M3 - Journal article
VL - 929
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 1
M1 - 92
ER -
ID: 304150436