The Simons Observatory: Validation of reconstructed power spectra from simulated filtered maps for the Small Aperture Telescope survey

Hervías-Caimapo, C., Calabrese, Erminia ORCID: https://orcid.org/0000-0003-0837-0068 and Giardiello, Serena 2025. The Simons Observatory: Validation of reconstructed power spectra from simulated filtered maps for the Small Aperture Telescope survey. [Online]. arXiv: Cornell University. Available at: https://doi.org/10.48550/arXiv.2502.00946

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Abstract

We present a transfer function-based method to estimate angular power spectra from filtered maps for cosmic microwave background (CMB) surveys. This is especially relevant for experiments targeting the faint primordial gravitational wave signatures in CMB polarisation at large scales, such as the Simons Observatory (SO) small aperture telescopes. While timestreams can be filtered to mitigate the contamination from low-frequency noise, usual methods that calculate the mode coupling at individual multipoles can be challenging for experiments covering large sky areas or reaching few-arcminute resolution. The method we present here, although approximate, is more practical and faster for larger data volumes. We validate it through the use of simulated observations approximating the first year of SO data, going from half-wave plate-modulated timestreams to maps, and using simulations to estimate the mixing of polarisation modes induced by an example of time-domain filtering. We show its performance through an example null test and with an end-to-end pipeline that performs inference on cosmological parameters, including the tensor-to-scalar ratio . The performance demonstration uses simulated observations at multiple frequency bands. We find that the method can recover unbiased parameters for our simulated noise levels.

Item Type:	Website Content
Date Type:	Submission
Status:	Submitted
Schools:	Schools > Physics and Astronomy
Additional Information:	Full list of authors: Carlos Hervias-Caimapo, Kevin Wolz, Adrien La Posta, Susanna Azzoni, David Alonso, Kam Arnold, Carlo Baccigalupi, Simon Biquard, Michael L. Brown, Erminia Calabrese, Yuji Chinone, Samuel Day-Weiss, Jo Dunkley, Rolando Dünner, Josquin Errard, Giulio Fabbian, Ken Ganga, Serena Giardiello, Emilie Hertig, Kevin M. HuffenbergerBradley R. Johnson, Baptiste Jost, Reijo Keskitalo, Theodore S. Kisner, Thibaut Louis, Magdy Morshed, Lyman A. Page, Christian L. Reichardt, Erik Rosenberg, Max Silva-Feaver, Wuhyun Sohn, Yoshinori Sueno, Dan B. Thomas, Ema Tsang King Sang, Amalia Villarrubia-Aguilar, Kyohei Yamada
Publisher:	Cornell University
Last Modified:	28 May 2025 15:38
URI:	https://orca.cardiff.ac.uk/id/eprint/176679

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