The ALMA REBELS Survey: The Cosmic H i Gas Mass Density in Galaxies at z approximate to 7
Publikation: Bidrag til tidsskrift › Letter › Forskning › fagfællebedømt
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The ALMA REBELS Survey : The Cosmic H i Gas Mass Density in Galaxies at z approximate to 7. / Heintz, K. E.; Oesch, P. A.; Aravena, M.; Bouwens, R. J.; Dayal, P.; Ferrara, A.; Fudamoto, Y.; Graziani, L.; Inami, H.; Sommovigo, L.; Smit, R.; Stefanon, M.; Topping, M.; Pallottini, A.; van der Werf, P.
I: Astrophysical Journal Letters, Bind 934, Nr. 2, 27, 01.08.2022.Publikation: Bidrag til tidsskrift › Letter › Forskning › fagfællebedømt
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TY - JOUR
T1 - The ALMA REBELS Survey
T2 - The Cosmic H i Gas Mass Density in Galaxies at z approximate to 7
AU - Heintz, K. E.
AU - Oesch, P. A.
AU - Aravena, M.
AU - Bouwens, R. J.
AU - Dayal, P.
AU - Ferrara, A.
AU - Fudamoto, Y.
AU - Graziani, L.
AU - Inami, H.
AU - Sommovigo, L.
AU - Smit, R.
AU - Stefanon, M.
AU - Topping, M.
AU - Pallottini, A.
AU - van der Werf, P.
PY - 2022/8/1
Y1 - 2022/8/1
N2 - The neutral atomic gas content of individual galaxies at large cosmological distances has until recently been difficult to measure due to the weakness of the hyperfine H I 21 cm transition. Here we estimate the H I gas mass of a sample of main-sequence star-forming galaxies at z similar to 6.5-7.8 surveyed for [C II] 158 mu m emission as part of the Reionization Era Bright Emission Line Survey (REBELS), using a recent calibration of the [C II]-to-H I conversion factor. We find that the H I gas mass excess in galaxies increases as a function of redshift, with an average of M-HI /M-star approximate to 10, corresponding to H I gas mass fractions of f(HI) = M-HI /(M-star + M-HI) = 90%, at z approximate to 7. Based on the [C II] 158 mu m luminosity function (LF) derived from the same sample of galaxies, we further place constraints on the cosmic H I gas mass density in galaxies (rho(HI)) at this redshift, which we measure to be rho(HI) = 7.1(-3.0)(+6.4) x 10(6) M-circle dot Mpc(-3). This estimate is substantially lower by a factor of approximate to 10 than that inferred from an extrapolation of damped Ly alpha absorber (DLA) measurements and largely depends on the exact [C II] LF adopted. However, we find this decrease in rho(HI) to be consistent with recent simulations and argue that this apparent discrepancy is likely a consequence of the DLA sight lines predominantly probing the substantial fraction of H I gas in high-z galactic halos, whereas [C II] traces the H I in the ISM associated with star formation. We make predictions for this buildup of neutral gas in galaxies as a function of redshift, showing that at z greater than or similar to 5, only approximate to 10% of the cosmic H I gas content is confined in galaxies and associated with the star-forming ISM.
AB - The neutral atomic gas content of individual galaxies at large cosmological distances has until recently been difficult to measure due to the weakness of the hyperfine H I 21 cm transition. Here we estimate the H I gas mass of a sample of main-sequence star-forming galaxies at z similar to 6.5-7.8 surveyed for [C II] 158 mu m emission as part of the Reionization Era Bright Emission Line Survey (REBELS), using a recent calibration of the [C II]-to-H I conversion factor. We find that the H I gas mass excess in galaxies increases as a function of redshift, with an average of M-HI /M-star approximate to 10, corresponding to H I gas mass fractions of f(HI) = M-HI /(M-star + M-HI) = 90%, at z approximate to 7. Based on the [C II] 158 mu m luminosity function (LF) derived from the same sample of galaxies, we further place constraints on the cosmic H I gas mass density in galaxies (rho(HI)) at this redshift, which we measure to be rho(HI) = 7.1(-3.0)(+6.4) x 10(6) M-circle dot Mpc(-3). This estimate is substantially lower by a factor of approximate to 10 than that inferred from an extrapolation of damped Ly alpha absorber (DLA) measurements and largely depends on the exact [C II] LF adopted. However, we find this decrease in rho(HI) to be consistent with recent simulations and argue that this apparent discrepancy is likely a consequence of the DLA sight lines predominantly probing the substantial fraction of H I gas in high-z galactic halos, whereas [C II] traces the H I in the ISM associated with star formation. We make predictions for this buildup of neutral gas in galaxies as a function of redshift, showing that at z greater than or similar to 5, only approximate to 10% of the cosmic H I gas content is confined in galaxies and associated with the star-forming ISM.
KW - STAR-FORMING GALAXIES
KW - MOLECULAR GAS
KW - INTERSTELLAR-MEDIUM
KW - SCALING RELATIONS
KW - DUST CONTENT
KW - REDSHIFT
KW - EMISSION
KW - EVOLUTION
KW - EPOCH
KW - REIONIZATION
U2 - 10.3847/2041-8213/ac8057
DO - 10.3847/2041-8213/ac8057
M3 - Letter
VL - 934
JO - The Astrophysical Journal Letters
JF - The Astrophysical Journal Letters
SN - 2041-8205
IS - 2
M1 - 27
ER -
ID: 315984345