On estimating the cosmic molecular gas density from CO Line Intensity Mapping observations

Abstract

The Millimeter-wave Intensity Mapping Experiment (mmIME) recently reported a detection of excess spatial fluctuations at a wavelength of 3 mm, which can be attributed to unresolved emission of several CO rotational transitions between $z\sim 1-5$. We study the implications of this data for the high-redshift interstellar medium using a suite of state-of-the-art semianalytic simulations which have successfully reproduced many other sub-millimeter line observations across the relevant redshift range. We find that the semianalytic predictions are mildly in tension with the mmIME result, with a predicted CO power $\sim 3.5\sigma$ below what was observed. We explore some simple modifications to the models which could resolve this tension. Increasing the molecular gas abundance at the relevant redshifts to $\sim 10^8{M}_{\odot }{\mathrm{Mpc}}^{-3}$, a value well above that obtained from directly imaged sources, would resolve the discrepancy, as would assuming a CO-$H_2$ conversion factor ${\alpha }_{\mathrm{CO}}$ of $\sim 1.5M_{\odot }$ K${}^{-1}$ $(\mathrm{km}/\mathrm{s}{)}^{-1}$ pc${}^2$, a value somewhat lower than is commonly assumed. We go on to demonstrate that these conclusions are quite sensitive to the detailed assumptions of our simulations, highlighting the need for more careful modeling efforts as more intensity mapping data become available.

arXiv comment15 pages, 8 figures, submitted to ApJ

References in corpus (77)

• Cosmic Star Formation History
• The CO-to-H2 Conversion Factor
• The Average Star Formation Histories of Galaxies in Dark Matter Halos from z=0-8
• The Cosmic Evolution Survey (COSMOS) -- Overview
• Toward a halo mass function for precision cosmology: the limits of universality
• Planck 2018 results. I. Overview and the cosmological legacy of Planck
• UniverseMachine: The Correlation between Galaxy Growth and Dark Matter Halo Assembly from z=0-10
• A Semi-Analytic Model for the Co-evolution of Galaxies, Black Holes, and Active Galactic Nuclei
• Cool Gas in High Redshift Galaxies
• Semi-Analytic Modelling of Galaxy Formation: The Local Universe
• MultiDark simulations: the story of dark matter halo concentrations and density profiles
• PHIBSS: molecular gas content and scaling relations in z~1-3 normal star forming galaxies
• The Evolution of the Star-forming Interstellar Medium across Cosmic Time
• How to Plant a Merger Tree
• Evolution of Interstellar Medium, Star Formation, and Accretion at High Redshift
• CO excitation of normal star forming galaxies out to z=1.5 as regulated by the properties of their interstellar medium
• The ALPINE-ALMA [CII] Survey: data processing, catalogs, and statistical source properties
• Galaxy Properties from the Ultra-violet to the Far-Infrared: Lambda-CDM models confront observations
• The [C II] emission as a molecular gas mass tracer in galaxies at low and high redshift
• Star Formation in Semi-Analytic Galaxy Formation Models with Multiphase Gas
• Evolution of the atomic and molecular gas content of galaxies
• Intensity Mapping with Carbon Monoxide Emission Lines and the Redshifted 21 cm Line
• Semi-analytic forecasts for JWST - I. UV luminosity functions at z = 4 - 10
• The ALMA Spectroscopic Survey in the HUDF: CO luminosity functions and the molecular gas content of galaxies through cosmic history
• Line-Intensity Mapping: 2017 Status Report
• COLDz: Shape of the CO Luminosity Function at High Redshift and the Cold Gas History of the Universe
• The Evolution of the Baryons Associated with Galaxies Averaged over Cosmic Time and Space
• Connecting CO Intensity Mapping to Molecular Gas and Star Formation in the Epoch of Galaxy Assembly
• PHIBSS2: survey design and z=0.5-0.8 results. Molecular gas reservoirs during the winding-down of star formation
• Semi-analytic forecasts for JWST -- II. physical properties and scaling relations for galaxies at z = 4-10
• The ALMA Spectroscopic Survey in the HUDF: Multi-band constraints on line luminosity functions and the cosmic density of molecular gas
• The CO Luminosity Density at High-z (COLDz) Survey: A Sensitive, Large Area Blind Search for Low-J CO Emission from Cold Gas in the Early Universe with the Karl G. Jansky Very Large Array
• Understanding the Structural Scaling Relations of Early-Type Galaxies
• A Molecular Line Scan in the Hubble Deep Field North: Constraints on the CO Luminosity Function and the Cosmic H2 Density
• COPSS II: The Molecular Gas Content of Ten Million Cubic Megaparsecs at $z\sim 3$
• Carbon monoxide line emission as a CMB foreground: tomography of the star-forming universe with different spectral resolutions
• DESPOTIC -- A New Software Library to Derive the Energetics and SPectra of Optically Thick Interstellar Clouds
• The ALMA Spectroscopic Survey in the HUDF: CO emission lines and 3 mm continuum sources
• The properties of the interstellar medium of galaxies across time as traced by the neutral atomic carbon [CI]
• On Removing Interloper Contamination from Intensity Mapping Power Spectrum Measurements
• Cross-correlations as a cosmological carbon monoxide detector
• The art of modeling CO, [CI], and [CII] in cosmological galaxy formation models
• A User's Guide to Extracting Cosmological Information from Line-Intensity Maps
• The ALMA Spectroscopic Survey in the HUDF: the molecular gas content of galaxies and tensions with IllustrisTNG and the Santa Cruz SAM
• The ALMA Spectroscopic Survey in the HUDF: The Cosmic Dust and Gas Mass Densities in Galaxies up to $z\sim 3$
• Sub-mm Emission Line Deep Fields: CO and [CII] Luminosity Functions out to z = 6
• Carbon Monoxide Intensity Mapping at Moderate Redshifts
• VLA-ALMA Spectroscopic Survey in the Hubble Ultra Deep Field (VLASPECS): Total Cold Gas Masses and CO Line Ratios for z=2-3 "Main Sequence" Galaxies
• Spectral Line De-confusion in an Intensity Mapping Survey
• An Intensity Mapping Detection of Aggregate CO Line Emission at 3 mm
• Cosmology with intensity mapping techniques using atomic and molecular lines
• Foreground contamination in Ly-alpha intensity mapping during the epoch of reionization
• Dissecting the high-z interstellar medium through intensity mapping cross-correlations
• Constraining the CO intensity mapping power spectrum at intermediate redshifts
• Line intensity mapping with [CII] and CO(1-0) as probes of primordial non-Gaussianity
• A Foreground Masking Strategy for [CII] Intensity Mapping Experiments Using Galaxies Selected by Stellar Mass and Redshift
• Mock Lightcones and Theory Friendly Catalogs for the CANDELS Survey
• Plateau de Bure High-z Blue-Sequence Survey 2 (PHIBSS2): Search for Secondary Sources, CO Luminosity Functions in the Field, and the Evolution of Molecular Gas Density through Cosmic Time
• A Self-consistent Framework for Multiline Modeling in Line Intensity Mapping Experiments
• Insights from probability distribution functions of intensity maps
• Joint power spectrum and voxel intensity distribution forecast on the CO luminosity function with COMAP
• Probing Cosmic Reionization and Molecular Gas Growth with TIME
• Evidence for CII diffuse line emission at redshift $z\sim 2.6$
• Cross-correlating Carbon Monoxide Line-intensity Maps with Spectroscopic and Photometric Galaxy Surveys
• Phase-Space Spectral Line De-confusion in Intensity Mapping
• Multitracer cosmological line intensity mapping mock lightcone simulation
• Molecular gas mass functions of normal star forming galaxies since z~3
• Molecular gas in distant galaxies from ALMA studies
• Observing AGN feedback with CO intensity mapping
• The cosmic abundance of cold gas in the local Universe
• The high redshift star-formation history from carbon-monoxide intensity maps
• Feeding cosmic star formation: Exploring high-redshift molecular gas with CO intensity mapping
• Canceling out intensity mapping foregrounds
• Measuring the average molecular gas content of star-forming galaxies at $z=3-4$
• Biases and Cosmic Variance in Molecular Gas Abundance Measurements
• A partial inventory of observational anisotropies in single-dish line-intensity mapping
• Optical Design of the EXperiment for Cryogenic Large-Aperture Intensity Mapping (EXCLAIM)

Cited by in corpus (12)

• COMAP Early Science: V. Constraints and Forecasts at $z\sim 3$
• COMAP Early Science: VII. Prospects for CO Intensity Mapping at Reionization
• [CII] line intensity mapping the epoch of reionization with the Prime-Cam on FYST
• An Intensity Mapping Constraint on the CO-Galaxy Cross Power Spectrum at Redshift ~ 3
• Probing Population III Initial Mass Functions with He II/H$\alpha$ Intensity Mapping
• Revisiting the [C II]${}_{158\mu \text{m}}$ line-intensity mapping power spectrum from the EoR using non-uniform line-luminosity scatter
• Constraining low redshift [CII] Emission by Cross-Correlating FIRAS and BOSS Data
• A Forecast for Large Scale Structure Constraints on Horndeski Gravity with Line Intensity Mapping
• Probing the Epoch of Reionization using synergies of line intensity mapping
• COMAP Pathfinder -- Season 2 results III. Implications for cosmic molecular gas content at "Cosmic Half-past Eleven"
• Reionization relics in the cross-correlation between the Ly$\alpha$ forest and 21 cm intensity mapping in the post-reionization era
• Unveiling the evolution of the CO excitation ladder through cross-correlation of CONCERTO-like experiments and galaxy redshift surveys