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Published February 1, 2013 | Published + Submitted
Journal Article Open

Intensity Mapping of Lyα Emission during the Epoch of Reionization


We calculate the absolute intensity and anisotropies of the Lyα radiation field present during the epoch of reionization. We consider emission from both galaxies and the intergalactic medium (IGM) and take into account the main contributions to the production of Lyα photons: recombinations, collisions, continuum emission from galaxies, and scattering of Lyn photons in the IGM. We find that the emission from individual galaxies dominates over the IGM with a total Lyα intensity (times frequency) of about (1.43-3.57) × 10^(–8) erg s^(–1) cm^(–2) sr^(–1) at a redshift of 7. This intensity level is low, so it is unlikely that the Lyα background during reionization can be established by an experiment aiming at an absolute background light measurement. Instead, we consider Lyα intensity mapping with the aim of measuring the anisotropy power spectrum that has rms fluctuations at the level of 1 × 10^(–16) [erg s^(–1) cm^(–2) sr^(–1)]^2 at a few Mpc scales. These anisotropies could be measured with a spectrometer at near-IR wavelengths from 0.9 to 1.4 μm with fields in the order of 0.5 to 1 deg^2. We recommend that existing ground-based programs using narrow band filters also pursue intensity fluctuations to study statistics on the spatial distribution of faint Lyα emitters. We also discuss the cross-correlation signal with 21 cm experiments that probe H I in the IGM during reionization. A dedicated sub-orbital or space-based Lyα intensity mapping experiment could provide a viable complimentary approach to probe reionization, when compared to 21 cm experiments, and is likely within experimental reach.

Additional Information

© 2013 American Astronomical Society. Received 2012 May 10; accepted 2012 November 30; published 2013 January 17. This work was supported by FCT-Portugal with the grant SFRH/BD/51373/2011 for M.B.S. and under grant PTDC/FIS/100170/2008 for M.B.S. and M.G.S. A.C. and Y.G. acknowledge support from NSF CAREER AST-0645427 and NASA NNX10AD42G at UCI. M.B.S. was a long-term Visiting Student at UCI, supported by NSF CAREER AST-0645427, when this work was initiated, and she thanks the Department of Physics and Astronomy at UCI for hospitality during her stay.

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Published - 0004-637X_763_2_132.pdf

Submitted - 1205.1493v2.pdf


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