An Empirically Calibrated [C II] Luminosity-Halo Mass Relation for Line Intensity Mapping
Abstract
Millimeter-wave line intensity mapping aims to observe the high-redshift universe through the 158 μm fine-structure line of [C II], the brightest far-infrared line of star-forming galaxies. Whether a [C II] experiment at z>4 measures the clustering of large-scale structure, which carries rich cosmological information, rather than the shot noise of the emitters depends on the amplitude and the shape of the [C II] power spectrum. Forecasts often build the power spectrum from a halo mass--luminosity relation, L(Mh), chained from scaling relations measured in other regimes or read off simulations, without a quantified uncertainty. We instead calibrate a double power-law L(Mh,z) on [C II] data alone: the mean [C II] intensity from tomographic cross-correlation at 0.4<z<4.2 and the luminosity-function measurements and limits at z≃0 and 4.3≲ z≲8. The four parameters of the double power law are fitted at z=4.5 and $5.5$ separately, with no assumption about their evolution, and then jointly across 0<z<7, and we examine how the uncertainty depends on the modeling assumptions. The shape of the power spectrum is settled by the existing data. The clustering peak stands a factor of 45 (23-93) and 64 (38-112) above the shot-noise floor at z=4.5 and $5.5$, and the two cross at kc≃0.37 and 0.44 hMpc−1. The amplitude is known less well, the clustering power to 0.5−0.6 dex and the shot noise to 0.7−0.9 dex. The results show that the signal comes from halos accessible by current galaxy surveys, those that host the Lyman-break galaxies and Lyα emitters at these redshifts. The luminosity-weighted bias is relatively high, with values of 4−5.
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BibTeX
@misc{jeong2026empirically,
title = {{An Empirically Calibrated [C II] Luminosity-Halo Mass Relation for Line Intensity Mapping}},
author = {Oliver Jeong and Martin White},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.40550},
eprint = {2610.40550},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.40550},
}
RIS
TY - UNPB
TI - An Empirically Calibrated [C II] Luminosity-Halo Mass Relation for Line Intensity Mapping
AU - Oliver Jeong
AU - Martin White
PY - 2026
DA - 2026/10/29
PB - arXiv
DO - 10.48550/arxiv.2610.40550
UR - https://arxiv.org/abs/2610.40550
AB - Millimeter-wave line intensity mapping aims to observe the high-redshift universe through the 158 μm fine-structure line of [C II], the brightest far-infrared line of star-forming galaxies. Whether a [C II] experiment at z>4 measures the clustering of large-scale structure, which carries rich cosmological information, rather than the shot noise of the emitters depends on the amplitude and the shape of the [C II] power spectrum. Forecasts often build the power spectrum from a halo mass--luminosity relation, L(M_h), chained from scaling relations measured in other regimes or read off simulations, without a quantified uncertainty. We instead calibrate a double power-law L(M_h,z) on [C II] data alone: the mean [C II] intensity from tomographic cross-correlation at 0.4<z<4.2 and the luminosity-function measurements and limits at z≃0 and 4.3≲ z≲8. The four parameters of the double power law are fitted at z=4.5 and $5.5$ separately, with no assumption about their evolution, and then jointly across 0<z<7, and we examine how the uncertainty depends on the modeling assumptions. The shape of the power spectrum is settled by the existing data. The clustering peak stands a factor of 45 (23-93) and 64 (38-112) above the shot-noise floor at z=4.5 and $5.5$, and the two cross at k_c≃0.37 and 0.44 hMpc^−1. The amplitude is known less well, the clustering power to 0.5−0.6 dex and the shot noise to 0.7−0.9 dex. The results show that the signal comes from halos accessible by current galaxy surveys, those that host the Lyman-break galaxies and Lyα emitters at these redshifts. The luminosity-weighted bias is relatively high, with values of 4−5.
ER -