ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: implications for spectral line intensity mapping at millimeter wavelengths and CMB spectral distortions

Abstract

We present direct estimates of the mean sky brightness temperature in observing bands around 99GHz and 242GHz due to line emission from distant galaxies. These values are calculated from the summed line emission observed in a blind, deep survey for specrtal line emission from high redshift galaxies using ALMA (the 'ASPECS' survey). In the 99 GHz band, the mean brightness will be dominated by rotational transitions of CO from intermediate and high redshift galaxies. In the 242GHz band, the emission could be a combination of higher order CO lines, and possibly [CII] 158$\mu$m line emission from very high redshift galaxies ($z\sim 6$ to 7). The mean line surface brightness is a quantity that is relevant to measurements of spectral distortions of the cosmic microwave background, and as a potential tool for studying large-scale structures in the early Universe using intensity mapping. While the cosmic volume and the number of detections are admittedly small, this pilot survey provides a direct measure of the mean line surface brightness, independent of conversion factors, excitation, or other galaxy formation model assumptions. The mean surface brightness in the 99GHZ band is: $T_B=0.94\pm 0.09$ $\mu$K. In the 242GHz band, the mean brightness is: $T_B=0.55\pm 0.033$ $\mu$K. These should be interpreted as lower limits on the average sky signal, since we only include lines detected individually in the blind survey, while in a low resolution intensity mapping experiment, there will also be the summed contribution from lower luminosity galaxies that cannot be detected individually in the current blind survey.

To appear the Astrophysical Journal, incorporating the first and second round of referee comments. Revised version 2 fixed typo in brightness units, equation, and text, and revised acknowledgements

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Cited by in corpus (11)

• ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Survey Description
• Line-Intensity Mapping: 2017 Status Report
• The REBELS ALMA Survey: cosmic dust temperature evolution out to z $\sim$ 7
• ALMA spectroscopic survey in the Hubble Ultra Deep Field: CO luminosity functions and the evolution of the cosmic density of molecular gas
• ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Molecular gas reservoirs in high-redshift galaxies
• Are high redshift Galaxies hot? - Temperature of z > 5 Galaxies and Implications on their Dust Properties
• The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: The nature of the faintest dusty star-forming galaxies
• Dust Properties of [CII] Detected z $\sim$ 5.5 Galaxies: New HST/WFC3 Near-IR Observations
• A NOEMA molecular line scan of the Hubble Deep Field North: Improved constraints on the CO luminosity functions and cosmic density of molecular gas
• The ALMA Spectroscopic Survey in the HUDF: Constraining cumulative CO emission at $1\lesssim z\lesssim 4$ with power spectrum analysis of ASPECS LP data from 84 to 115 GHz
• CONCERTO: Extracting the power spectrum of the [C II ] emission line