We forecast that the Terahertz Intensity Mapper (TIM) cross-correlated with Euclid's Fornax deep field (EDF-F), TIM×EDF-F, will detect the [CII]-galaxy cross-power spectrum at a median redshift of 1.1 with ≳7σ confidence. The Poisson component of the cross-power spectrum at 0.1≤k≤10 hMpc−1 (i.e. cross-shot noise) will be detected at ≳3σ in 4 bins spanning 0.5<z<1.7. This measurement will constrain the mean [CII] specific intensity over half of cosmic history and assess the degree to which Euclid-selected galaxies account for the [CII] intensity observed by TIM. We find that TIM can detect the cross-power spectrum across a wide range of [CII] intensity models.
@article{arxiv.2602.24204,
title = {Forecasting the cross correlation of Terahertz Intensity Mapper [CII] line intensity maps with Euclid galaxies},
author = {Justin S. Bracks and Ryan P. Keenan and Shubh Agrawal and Garrett K. Keating and James E. Aguirre and Adam Lidz and Charles M. Bradford and Brockton Brendal and Jeffrey Filippini and Jianyang Fu and Karolina Garcia and Christopher Groppi and Steven Hailey-Dunsheath and Reinier M. J. Janssen and Wooseok Kang and Lun-Jun Liu and Ian Lowe and Alex Manduca and Daniel P. Marrone and Philip Mauskopf and Evan C. Mayer and Sydnee O'Donnell and Talia Saeid and Simon Tartakovsky and Mathilde Cuyck and Joaquin D. Vieira and Jessica A. Zebrowski},
journal= {arXiv preprint arXiv:2602.24204},
year = {2026}
}