The ALMA REBELS Survey: The Cosmic HI Gas Mass Density in Galaxies at $z\approx 7$

Abstract

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 HI 21-cm transition. Here we estimate the HI gas mass of a sample of main-sequence star-forming galaxies at $z\sim 6.5-7.8$ surveyed for [CII]$-158\mu$m emission as part of the Reionization Era Bright Emission Line Survey (REBELS), using a recent calibration of the [CII]-to-HI conversion factor. We find that the HI gas mass excess in galaxies increases as a function of redshift, with an average of $M_{\mathrm{HI}}/M_{\star }\approx 10$, corresponding to HI gas mass fractions of $f_{\mathrm{HI}}=M_{\mathrm{HI}}/(M_{\star }+M_{\mathrm{HI}})=90\%$, at $z\approx 7$. Based on the [CII]-$158\mu$m luminosity function (LF) derived from the same sample of galaxies, we further place constraints on the cosmic HI gas mass density in galaxies (${\rho }_{\mathrm{HI}}$) at this redshift, which we measure to be ${\rho }_{\mathrm{HI}}=7.1_{-3.0}^{+6.4}\times 10^6{M}_{\odot }\mathrm{Mp}{\mathrm{c}}^{-3}$. This estimate is substantially lower by a factor of $\approx 10$ than that inferred from an extrapolation of damped Lyman-$\alpha$ absorber (DLA) measurements, and largely depend on the exact [CII] LF adopted. However, we find this decrease in ${\rho }_{\mathrm{HI}}$ to be consistent with recent simulations and argue that this apparent discrepancy is likely a consequence of the DLA sightlines predominantly probing the substantial fraction of HI gas in high-$z$ galactic halos, whereas [CII] traces the HI in the ISM associated with star formation. We make predictions for this build-up of neutral gas in galaxies as a function of redshift, showing that at $z\gtrsim 5$ only $\approx 10\%$ of the cosmic HI gas content is confined in galaxies and associated with the star-forming ISM.

arXiv commentThe accepted version of the manuscript in press for ApJL

References in corpus (76)

• The chemical composition of the Sun
• Galactic Stellar and Substellar Initial Mass Function
• Star Formation in Galaxies Along the Hubble Sequence
• The CO-to-H2 Conversion Factor
• The Star Formation Efficiency in Nearby Galaxies: Measuring Where Gas Forms Stars Effectively
• THINGS: The HI Nearby Galaxy Survey
• Cool Gas in High Redshift Galaxies
• High molecular gas fractions in normal massive star forming galaxies in the young Universe
• Gas-to-Dust mass ratios in local galaxies over a 2 dex metallicity range
• PHIBSS: Unified Scaling Relations of Gas Depletion Time and Molecular Gas Fractions
• The Evolving Interstellar Medium of Star Forming Galaxies Since z=2 as Probed by Their Infrared Spectral Energy Distributions
• Deriving Physical Properties from Broadband Photometry with Prospector: Description of the Model and a Demonstration of its Accuracy Using 129 Galaxies in the Local Universe
• The Interstellar Medium In Galaxies Seen A Billion Years After The Big Bang
• The Evolution of the Star-forming Interstellar Medium across Cosmic Time
• The HIPASS catalogue: Omega_HI and environmental effects on the HI mass function of galaxies
• New Determinations of the UV Luminosity Functions from z~9 to z~2 show a remarkable consistency with halo growth and a constant star formation efficiency
• xGASS: Total cold gas scaling relations and molecular-to-atomic gas ratios of galaxies in the local Universe
• The Mass-Metallicity and the Fundamental Metallicity Relation revisited on a fully Te-based abundance scale for galaxies
• Evolution of Interstellar Medium, Star Formation, and Accretion at High Redshift
• Column density distribution and cosmological mass density of neutral gas: Sloan Digital Sky Survey-III Data Release 9
• On the (Non)Evolution of HI Disks over Cosmic Time
• The Cosmic Baryon and Metal Cycles
• The MOSDEF Survey: The Evolution of the Mass-Metallicity Relation from $z=0$ to $z\sim 3.3$
• An Overview of the Dwarf Galaxy Survey
• The ALPINE-ALMA [CII] Survey: data processing, catalogs, and statistical source properties
• "Big Three Dragons": a z = 7.15 Lyman BreakGalaxy Detected in [OIII] 88 $\mu$m, [CII] 158 $\mu$m, and Dust Continuum with ALMA
• The evolution of Omega(HI) and the epoch of formation of damped Lyman-alpha absorbers
• The [C II] emission as a molecular gas mass tracer in galaxies at low and high redshift
• Star-Forming Galaxies at Cosmic Noon
• The Herschel Dwarf Galaxy Survey: I. Properties of the low-metallicity ISM from PACS spectroscopy
• Rotation in [CII]-emitting gas in two galaxies at a redshift of 6.8
• The CI lines as tracers of molecular gas, and their prospects at high redshifts
• Reionization Era Bright Emission Line Survey: Selection and Characterization of Luminous Interstellar Medium Reservoirs in the z>6.5 Universe
• The ALFALFA HI mass function: A dichotomy in the low-mass slope and a locally suppressed 'knee' mass
• The ESO UVES Advanced Data Products Quasar Sample - II. Cosmological Evolution of the Neutral Gas Mass Density
• The HI content of star-forming galaxies at z = 0.24
• The ALMA Spectroscopic Survey in the HUDF: CO luminosity functions and the molecular gas content of galaxies through cosmic history
• A Survey of Atomic Carbon at High Redshift
• COLDz: Shape of the CO Luminosity Function at High Redshift and the Cold Gas History of the Universe
• The ALPINE-ALMA [CII] Survey: Multi-Wavelength Ancillary Data and Basic Physical Measurements
• The Evolution of the Baryons Associated with Galaxies Averaged over Cosmic Time and Space
• Deep into the structure of the first galaxies: SERRA views
• Cosmological evolution of atomic gas and implications for 21 cm HI absorption
• The REBELS ALMA Survey: cosmic dust temperature evolution out to z $\sim$ 7
• A Herschel [CII] Galactic plane survey III: [CII] as a tracer of star formation
• The ALMA REBELS Survey: Dust Continuum Detections at z > 6.5
• Interpreting ALMA Observations of the ISM During the Epoch of Reionisation
• The ALMA REBELS Survey: the dust content of $z\sim 7$ Lyman Break Galaxies
• Astraeus I: The interplay between galaxy formation and reionization
• A Survey of Atomic Carbon [C I] in High-redshift Main-Sequence Galaxies
• Highest Redshift Image of Neutral Hydrogen in Emission: A CHILES Detection of a Starbursting Galaxy at z=0.376
• The Origins of [CII] Emission in Local Star-forming Galaxies
• The Keck+Magellan Survey for Lyman Limit Absorption I: The Frequency Distribution of Super Lyman Limit Systems
• The ALMA REBELS Survey. Epoch of Reionization giants: properties of dusty galaxies at $z\approx 7$
• A Molecular Line Scan in the Hubble Deep Field North: Constraints on the CO Luminosity Function and the Cosmic H2 Density
• MIGHTEE-HI: The HI emission project of the MeerKAT MIGHTEE survey
• Resolved UV and [CII] structures of luminous galaxies within the epoch of reionisation
• HI 21-centimetre emission from an ensemble of galaxies at an average redshift of one
• The HI Content of the Universe over the Past 10 Gyrs
• An ALMA multi-line survey of the interstellar medium of the redshift 7.5 quasar host galaxy J1342+0928
• The Mass-Metallicity Relation at z=8: Direct-Method Metallicity Constraints and Near-Future Prospects
• Physical constraints on the extended interstellar medium of the z=6.42 quasar J1148+5251: [CII] 158um, [NII] 205um and [OI] 146um observations
• Molecular clouds photoevaporation and FIR line emission
• The gas mass of star-forming galaxies at $z\approx 1.3$
• A metal-poor damped Ly-alpha system at redshift 6.4
• Tracing Molecular Gas in z $\simeq$ 6 Galaxies with [C$\mathrm{II}$]
• [CII] 158 Micron Emission from z~4 HI Absorption-Selected Galaxies
• Giant Metrewave Radio Telescope Detection of HI 21 cm Emission from Star-forming Galaxies at $z\approx 1.3$
• Neutral CGM as damped Lyα absorbers at high redshift
• The ALPINE-ALMA [C II] Survey: [C II]158micron Emission Line Luminosity Functions at $z\sim 4-6$
• Direct measurement of the [CI] luminosity to molecular gas mass conversion factor in high-redshift star-forming galaxies
• The First Large Absorption Survey in HI (FLASH): I. Science Goals and Survey Design
• The evolution of neutral hydrogen over the past 11 Gyr via HI 21 cm absorption
• Atomic and molecular gas from the epoch of reionization down to redshift 2
• Cosmic metal density evolution in neutral gas: insights from observations and cosmological simulations
• An Ultraviolet Survey of Low-Redshift Partial Lyman-Limit Systems with the HST Cosmic Origins Spectrograph

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