Spectral Line De-confusion in an Intensity Mapping Survey
Spectral line intensity mapping (LIM) has been proposed as a promising tool to efficiently probe the cosmic reionization and the large-scale structure. Without detecting individual sources, LIM makes use of all available photons and measures the integrated light in the source confusion limit to efficiently map the three-dimensional matter distribution on large scales as traced by a given emission line. One particular challenge is the separation of desired signals from astrophysical continuum foregrounds and line interlopers. Here we present a technique to extract large-scale structure information traced by emission lines from different redshifts, embedded in a three-dimensional intensity mapping data cube. The line redshifts are distinguished by the anisotropic shape of the power spectra when projected onto a common coordinate frame. We consider the case where high-redshift [C ii] lines are confused with multiple low-redshift CO rotational lines. We present a semi-analytic model for [C ii] and CO line estimates based on the cosmic infrared background measurements, and show that with a modest instrumental noise level and survey geometry, the large-scale [C ii] and CO power spectrum amplitudes can be successfully extracted from a confusion-limited data set, without external information. We discuss the implications and limits of this technique for possible LIM experiments.
Additional Information© 2016. The American Astronomical Society. Received 2016 April 26; revised 2016 September 19; accepted 2016 September 26; published 2016 November 30. We are grateful to the Time-Pilot collaboration for providing useful inputs throughout this work. We thank Phil Bull, Olivier Doré Tony Li, Adam Lidz, Roland de Putter, Paolo Serra, Chun-Hao To, and Heidi Hao-Yi Wu for helpful discussions and valuable comments on the manuscript. Y.-T.C. and T.-C.C. were supported in part by MoST grant 103-2112-M-001-002-MY3. T.-C.C. gratefully acknowledges the hospitality of the Caltech OBSCOS group and the Jet Propulsion Laboratory, where part of this work was carried out.
Published - Cheng_2016_ApJ_832_165.pdf
Submitted - 1604.07833v2.pdf