Emission line stacking on cosmological scales: equivalence to two-point statistics and modelling of the observational effects
Abstract
Emission line stacking measurement for cosmological line intensity mapping (LIM) contains not only the average emission line profile of the stacked sources, but usually also the clustering signal, due to the limited angular resolution of the observations. We provide an explicit derivation of the equivalence between the emission line stacking, the two-point cross-correlation function in configuration space and the power spectrum in Fourier space, similar to the case between the angular stacking signal for the kinematic Sunyaev-Zel'dovich effect and the angular power spectrum in harmonic space (arXiv:2512.14625, arXiv:2605.15947). Using the quadratic estimator formalism, we establish that the emission line stacking signal measurement is equivalent to a quadratic estimator for the cross-correlation function. The formalism allows for the explicit modelling of the stacked signal, including the clustering statistics as well as observational effects such as the galaxy selection function and the LIM survey footprint. In particular, using mock HI intensity mapping data, we show that we can accurately model the effects of foreground removal on the stacked signal. The correlation function estimator provides significant speed-up for the stacking measurement and enables modelling of the signal and its covariance for large LIM datasets with MeerKLASS and future SKAO.
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BibTeX
@misc{chen2026emission,
title = {{Emission line stacking on cosmological scales: equivalence to two-point statistics and modelling of the observational effects}},
author = {Zhaoting Chen and José Luis Bernal},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.33603},
eprint = {2610.33603},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.33603},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Emission line stacking on cosmological scales: equivalence to two-point statistics and modelling of the observational effects
AU - Zhaoting Chen
AU - José Luis Bernal
PY - 2026
DA - 2026/10/24
PB - arXiv
DO - 10.48550/arxiv.2610.33603
UR - https://arxiv.org/abs/2610.33603
AB - Emission line stacking measurement for cosmological line intensity mapping (LIM) contains not only the average emission line profile of the stacked sources, but usually also the clustering signal, due to the limited angular resolution of the observations. We provide an explicit derivation of the equivalence between the emission line stacking, the two-point cross-correlation function in configuration space and the power spectrum in Fourier space, similar to the case between the angular stacking signal for the kinematic Sunyaev-Zel'dovich effect and the angular power spectrum in harmonic space (arXiv:2512.14625, arXiv:2605.15947). Using the quadratic estimator formalism, we establish that the emission line stacking signal measurement is equivalent to a quadratic estimator for the cross-correlation function. The formalism allows for the explicit modelling of the stacked signal, including the clustering statistics as well as observational effects such as the galaxy selection function and the LIM survey footprint. In particular, using mock HI intensity mapping data, we show that we can accurately model the effects of foreground removal on the stacked signal. The correlation function estimator provides significant speed-up for the stacking measurement and enables modelling of the signal and its covariance for large LIM datasets with MeerKLASS and future SKAO.
ER -