The Atacama Cosmology Telescope: Constraints on Local Non-Gaussianity from the ACT Cluster Catalog

Leonid Sarieddine; J. Richard Bond; Matt Hilton; Raul Jimenez; Arthur Kosowsky; Kavilan Moodley; Bernardita Ried Guachalla; Cristóbal Sifón; Suzanne T. Staggs; Licia Verde; Edward J. Wollack

arXiv · 2602.03917

The Atacama Cosmology Telescope: Constraints on Local Non-Gaussianity from the ACT Cluster Catalog

Leonid Sarieddine·J. Richard Bond·Matt Hilton·Raul Jimenez·Arthur Kosowsky·Kavilan Moodley·Bernardita Ried Guachalla·Cristóbal Sifón·Suzanne T. Staggs·Licia Verde·Edward J. Wollack

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Abstract

We derive constraints on local-type primordial non-Gaussianity using the ACT DR6 Sunyaev--Zel'dovich cluster catalog. Modeling the redshift- and mass-dependent number counts of 1,201 clusters in the 10,347~deg$^2$ Legacy region, and accounting for survey completeness, intrinsic SZ scatter, and a weak-lensing-calibrated mass bias, we compute theoretical abundances using the Log--Edgeworth halo mass function. Assuming $\Lambda$CDM with well-motivated external priors, we obtain $f_{\rm NL} = 55 \pm 125$ (68% CL), consistent with Gaussian initial conditions. These constraints probe comoving scales of $5$--$10~{\rm Mpc}~h^{-1}$, complementing CMB bispectrum and scale-dependent bias measurements, which do not reach such small scales. We also find evidence for a 16.4% residual mass bias, which, although heavily informed by our adopted priors, plays a key role in matching observed and predicted counts but has negligible effect on $f_{\rm NL}$ constraints. We briefly discuss robustness of the results under relaxed priors and the prospects for next-generation SZ and lensing surveys to strengthen cluster-based tests of primordial non-Gaussianity.

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Leonid Sarieddine, J. Richard Bond, Matt Hilton, Raul Jimenez, Arthur Kosowsky, Kavilan Moodley, Bernardita Ried Guachalla, Cristóbal Sifón, Suzanne T. Staggs, Licia Verde, Edward J. Wollack. 2026-02-03. The Atacama Cosmology Telescope: Constraints on Local Non-Gaussianity from the ACT Cluster Catalog. https://arxiv.org/abs/2602.03917

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