Map-based asymmetric beam treatment: application of real-space beam patterns in CMB data analysis
Year: 2026
Type: preprint
Abstract: Real telescope beams are asymmetric, breaking the simple $B_{\ell}$ factorisation in harmonic space and coupling modes across $\ell$ and $m$. We develop a map-domain treatment in which beam convolution is a local, scan-dependent operation applied directly to the time-ordered data (TOD), accommodating the full beam shape and giving a direct handle on intensity-to-polarisation ($I \rightarrow P$) leakage. A noiseless validation against spherical-harmonic convolution reproduces the input temperature and $B$-mode power spectra up to $\ell \simeq 1000$, well beyond the range of primordial $B$-mode science. We outline how the operation maps onto a sparse linear BeamOperator for modular map-making.
Source: arXiv (Cornell University)
Author: Basyrov, Artem
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7220664354