Cross-correlating Squared kSZ and HI Intensity Fields: A Map-level ACT--MeerKAT Forecast

@misc{jiang2026crosscorrelating,
  title = {{Cross-correlating Squared kSZ and HI Intensity Fields: A Map-level ACT--MeerKAT Forecast}},
  author = {Yu-Er Jiang and Yun Liu and Yan Gong and Zi-Yan Yuwen and Yin-Zhe Ma and Furen Deng and Xuelei Chen and Qi Guo},
  howpublished = {arXiv},
  year = {2026},
  month = sep,
  doi = {10.48550/arxiv.2609.36863},
  eprint = {2609.36863},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2609.36863},
}

TY  - UNPB
TI  - Cross-correlating Squared kSZ and HI Intensity Fields: A Map-level ACT--MeerKAT Forecast
AU  - Yu-Er Jiang
AU  - Yun Liu
AU  - Yan Gong
AU  - Zi-Yan Yuwen
AU  - Yin-Zhe Ma
AU  - Furen Deng
AU  - Xuelei Chen
AU  - Qi Guo
PY  - 2026
DA  - 2026/09/29
PB  - arXiv
DO  - 10.48550/arxiv.2609.36863
UR  - https://arxiv.org/abs/2609.36863
AB  - The kinetic Sunyaev--Zel'dovich (kSZ) effect probes the line-of-sight momentum of free electrons, but its blackbody spectrum and velocity-dependent sign make it difficult to isolate and cause conventional cross-correlations with density tracers to vanish. In this work, we investigate the cross-correlation of the squared kSZ field with the projected squared HI intensity field using mock ACT and MeerKAT observations constructed from a Jiutian-1G simulation lightcone. We generate halo-based kSZ maps and MeerKAT-like HI brightness-temperature cubes over a 13.5^∘×13.5^∘ field. The simulations incorporate ACT beam smoothing and effective internal-linear-combination noise, together with the frequency-dependent MeerKAT beam, scanning strategy, map-making, and inhomogeneous thermal noise. We analyze signal-only, idealized amplitude-reconstructed, and Wiener-filtered kSZ maps. The resulting squared-field cross-correlations have diagnostic cumulative signal-to-noise ratios of approximately $3−4$. Our map-level results demonstrate the detectability of the kSZ^2× HI^2 correlation in future joint ACT--MeerKAT observations.
ER  -