The Atacama Cosmology Telescope: semi-analytic covariance matrices for the DR6 CMB power spectra
Abstract The Atacama Cosmology Telescope Data Release 6 (ACT DR6) power spectrum is expected to provide state-of-the-art cosmological constraints, with an associated need for precise error modeling. In this paper we design, and evaluate the performance of, an analytic covariance matrix prescription for the DR6 power spectrum that sufficiently accounts for the complicated ACT map properties. We use recent advances in the literature to handle sharp features in the signal and noise power spectra, and account for the effect of map-level anisotropies on the covariance matrix. In including inhomogeneous survey depth information, the resulting covariance matrix prescription is structurally similar to that used in the Planck Cosmic Microwave Background (CMB) analysis. We quantify the performance of our prescription using comparisons to Monte Carlo simulations, finding better than 3% agreement. This represents an improvement from a simpler, pre-existing prescription, which differs from simulations by ∼ 16%. We develop a new method to correct the analytic covariance matrix using simulations, after which both prescriptions achieve better than 1% agreement. This correction method outperforms a commonly used alternative, where the analytic correlation matrix is assumed to be accurate when correcting the covariance. Beyond its use for ACT, this framework should be applicable for future high resolution CMB experiments including the Simons Observatory (SO).
Authors
- Carlos Hervías-Caimapo (ORCID: https://orcid.org/0000-0002-4765-3426)
- Jo Dunkley (ORCID: https://orcid.org/0000-0002-7450-2586)
- Hidde T. Jense (ORCID: https://orcid.org/0000-0002-9429-0015)
- Michael D. Niemack (ORCID: https://orcid.org/0000-0001-7125-3580)
- Zachary Atkins (ORCID: https://orcid.org/0000-0002-2287-1603)
- Lyman A. Page (ORCID: https://orcid.org/0000-0002-9828-3525)
- Adriaan J. Duivenvoorden (ORCID: https://orcid.org/0000-0003-2856-2382)
- David Alonso (ORCID: https://orcid.org/0000-0002-4598-9719)
- Thibaut Louis (ORCID: https://orcid.org/0000-0002-6849-4217)
- Zack Li (ORCID: https://orcid.org/0000-0002-0309-9750)
- Erminia Calabrese (ORCID: https://orcid.org/0000-0003-0837-0068)
- Cristobál Sifón (ORCID: https://orcid.org/0000-0002-8149-1352)
- S. Giardiello (ORCID: https://orcid.org/0000-0002-8340-3715)
- J. Colin Hill (ORCID: https://orcid.org/0000-0002-9539-0835)
- Edward J. Wollack (ORCID: https://orcid.org/0000-0002-7567-4451)
- T. W. Morris (ORCID: https://orcid.org/0000-0002-5564-997X)
- Joshua Kim
- J. Richard Bond (ORCID: https://orcid.org/0000-0003-2358-9949)
Institutions
- Laboratoire de Physique des 2 Infinis Irène Joliot-Curie (FR)
Publication Details
- Journal
- Journal of Cosmology and Astroparticle Physics
- Published
- 2025-05-01
- DOI
- https://doi.org/10.1088/1475-7516/2025/05/015
- Citations
- 5
- Primary Topic
- Astronomy and Astrophysical Research
- Type
- article
- Field-Weighted Citation Impact
- 5.96
Funders
- National Science Foundation
- National Aeronautics and Space Administration
- Princeton University
- University of Pennsylvania
- Compute Canada
- Government of Ontario
- UK Research and Innovation
- National Energy Research Scientific Computing Center
- Flatiron Health
- National Research Foundation
- University of Toronto
- Agencia Nacional de Investigación y Desarrollo
- National Institute of Standards and Technology
- Science and Technology Facilities Council