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Line-intensity Mapping in the Era of JWST

Presentation #310.06 in the session “Cosmology 1”.

Published onJan 11, 2021
Line-intensity Mapping in the Era of JWST

Line-intensity mapping is a technique to measure the large-scale three-dimensional clustering of spectral line emission from galaxies or the intergalactic medium. This technique may be especially useful for studying the high-redshift universe, where faint sources are challenging to detect individually, but can contribute significantly to the intensity mapping signal due to their large numbers. A variety of instruments have recently been proposed or developed to observe intensity maps. These include radio observatories such as the Hydrogen Epoch of Reionization Array (HERA), which will measure the 21cm line from neutral hydrogen to understand cosmic reionization and the era of the first stars. Additionally, emission lines from high-redshift galaxies during the epoch of reionization (e.g. CO rotational lines, CII (158 microns), Lyman-alpha) can be measured in intensity maps with instruments such as COMAP, CONCERTO, and SPHEREx. A serious challenge in many intensity mapping experiments is the presence of bright foregrounds that must be removed to study the cosmological signal (e.g. galactic synchrotron emission in the case of 21cm observations). I will present recent theoretical work demonstrating that possible spurious residual foregrounds can be mitigated by cross correlating line-intensity maps and high-redshift galaxy observations from the James Webb Space Telescope (JWST). The field of view of JWST is small compared to typical intensity mapping surveys (several arcminutes compared to many degrees in some cases). However, it will be possible to cross correlate a sparse distribution of JWST fields within a larger intensity mapping field. I will discuss the formalism to predict the uncertainty on the power spectrum of such a cross correlation. Additionally, I will present representative examples illustrating the value of JWST-intensity mapping cross correlation during the epoch of reionization.

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