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Published April 20, 2019 | Submitted + Published
Journal Article Open

Multi-component Decomposition of Cosmic Infrared Background Fluctuations


The near-infrared background between 0.5 and 2 μm contains a wealth of information related to radiative processes in the universe. Infrared background anisotropies encode the redshift-weighted total emission over cosmic history, including any spatially diffuse and extended contributions. The anisotropy power spectrum is dominated by undetected galaxies at small angular scales and a diffuse background of Galactic emission at large angular scales. In addition to these known sources, the infrared background also arises from intrahalo light (IHL) at z < 3 associated with tidally stripped stars during galaxy mergers. Moreover, it contains information on the very first galaxies from the epoch of reionization (EoR). The EoR signal has a spectral energy distribution (SED) that goes to zero near optical wavelengths due to Lyman absorption, while other signals have spectra that vary smoothly with frequency. Due to differences in SEDs and spatial clustering, these components may be separated in a multi-wavelength-fluctuation experiment. To study the extent to which EoR fluctuations can be separated in the presence of IHL, and extragalactic and Galactic foregrounds, we develop a maximum likelihood technique that incorporates a full covariance matrix among all the frequencies at different angular scales. We apply this technique to simulated deep imaging data over a 2 × 45 deg^2 sky area from 0.75 to 5 μm in 9 bands and find that such a "frequency tomography" can successfully reconstruct both the amplitude and spectral shape for representative EoR, IHL, and the foreground signals.

Additional Information

© 2019. The American Astronomical Society. Received 2018 August 23; revised 2019 February 27; accepted 2019 March 5; published 2019 April 17. We thank the SPHEREx team for insightful comments that improved the quality of the paper. Part of the research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. C.F. acknowledges support from NASA grants NASA NNX16AJ69G, NASA NNX16AF39G, Ax Foundation for Cosmology at UC San Diego, and the Brand and Monica Fortner Chair. M.B.S. acknowledges the Netherlands Foundation for Scientific Research support through the VICI grant 639.043.006. M.G.S. acknowledges support from the South African Square Kilometre Array Project and National Research Foundation (grant No. 84156).

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Published - Feng_2019_ApJ_875_86.pdf

Submitted - 1808.05964.pdf


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August 22, 2023
October 20, 2023