A Foreground Masking Strategy for [C II] Intensity Mapping Experiments Using Galaxies Selected by Stellar Mass and Redshift

Abstract

Intensity mapping provides a unique means to probe the epoch of reionization (EoR), when the neutral intergalactic medium was ionized by energetic photons emitted from the first galaxies. The [C II] 158 mu m fine-structure line is typically one of the brightest emission lines of star-forming galaxies and thus a promising tracer of the global EoR star formation activity. However, [C II] intensity maps at 6 less than or similar to z less than or similar to 8 are contaminated by interloping CO rotational line emission (3 10(8) M-circle dot selected in the K-band from the COSMOS/UltraVISTA survey, which can be converted to CO line strengths. For a mock field of the Tomographic Ionizedcarbon Mapping Experiment, we find that masking out the "voxels" (spectral-spatial elements) containing foreground galaxies identified using an optimized CO flux threshold results in a z-dependent criterion m(K)(AB) less than or similar to 22 (or M-* greater than or similar to 10(9) M-circle dot) at z &lt;1 and makes a [C II]/COtot power ratio of greater than or similar to 10 at k = 0.1 h/Mpc achievable, at the cost of a moderate less than or similar to 8% loss of total survey volume.</p