Phase-Space Spectral Line De-confusion in Intensity Mapping

Kavli Affiliate: James J. Bock

| First 5 Authors: Yun-Ting Cheng, Tzu-Ching Chang, James J. Bock, ,

| Summary:

Line intensity mapping (LIM) is a promising tool to efficiently probe the
three-dimensional large-scale structure by mapping the aggregate emission of a
spectral line from all sources that trace the matter density field. Spectral
lines from different redshifts can fall in the same observed frequency and be
confused, however, which is a major challenge in LIM. In this work, we develop
a line de-confusion technique in map space capable of reconstructing the
three-dimensional spatial distribution of line-emitting sources. If multiple
spectral lines of a source population are observable in multiple frequencies,
using the sparse approximation, our technique iteratively extracts sources
along a given line of sight by fitting the LIM data to a set of spectral
templates. We demonstrate that the technique successfully extracts sources with
emission lines present at a few $sigma$ above the noise level, taking into
account uncertainties in the source modeling and presence of continuum
foreground contamination and noise fluctuations. As an example, we consider a
TIME/CONCERTO-like survey targeting [C II] at the epoch of reionization, and
reliably reconstruct the 3D spatial distribution of the CO interlopers at
$0.5lesssim zlesssim 1.5$. We also demonstrate a successful de-confusion for
the SPHEREx mission in the near-infrared wavelengths. Potentially, the
reconstructed maps can be further cross-correlated with a (galaxy) tracer
population to estimate the total interloper power in the linear clustering
regime. This technique is a general framework to extract the phase-space
distribution of low-redshift interlopers, without the need of external
information, for any line de-confusion problem.

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