Fast far-sidelobe modeling for centimeter to sub-millimeter astrophysical observations

TL;DR

This paper introduces a fast, diffraction-based modeling method for far-sidelobe response in next-generation telescopes, enabling efficient design and optimization for precise measurements of faint cosmic signals.

Contribution

A novel, computationally efficient diffraction-based beam modeling technique for rapid far-sidelobe prediction in astrophysical telescopes.

Findings

Good qualitative agreement with in situ measurements.

Effective in optimizing instrument baffling and scan strategies.

Rapid computation enables better instrument design.

Abstract

Next-generation centimeter to sub-millimeter telescopes require exquisite control over instrumental far-sidelobe response to accurately measure faint signals like the Cosmic Microwave Background B modes. Because existing electromagnetic modeling methods are computationally expensive, we developed a novel, diffraction-based beam modeling method for rapid and low-cost calculations. We applied this methodology to model the BICEP3 far-sidelobes and found good qualitative agreement with in situ beam measurements. Using this validated simulated beam, we calculated the sidelobe temperature pickup for a specific observation scenario: scanning near the slopes of Cerro Toco in the Atacama Desert. This rapid, predictive framework is most valuable as a tool for optimizing instrument baffling and identifying efficient scan strategies during the conceptual design phase.