Simulation of the cosmic ray effects for the LiteBIRD satellite observing the CMB B-mode polarization

TL;DR

This paper presents a comprehensive simulation study to evaluate the impact of cosmic-ray hits on the LiteBIRD satellite's measurements of CMB B-mode polarization, highlighting potential systematic uncertainties.

Contribution

It introduces an end-to-end simulation framework for assessing cosmic-ray effects on LiteBIRD's detectors, a novel approach for this mission.

Findings

CR hits could produce a $C_l^{BB}$ of about 2 x 10^{-6} μK^2 in one year

Simulations demonstrate procedures to generate maps and power spectra from time-ordered data

Initial results suggest cosmic rays are a significant source of systematic uncertainty

Abstract

The LiteBIRD satellite is planned to be launched by JAXA in the late 2020s. Its main purpose is to observe the large-scale B-mode polarization in the Cosmic Microwave Background (CMB) anticipated from the Inflation theory. LiteBIRD will observe the sky for three years at the second Lagrangian point (L2) of the Sun-Earth system. Planck was the predecessor for observing the CMB at L2, and the onboard High Frequency Instrument (HFI) suffered contamination by glitches caused by the cosmic-ray (CR) hits. We consider the CR hits can also be a serious source of the systematic uncertainty for LiteBIRD. Thus, we have started a comprehensive end-to-end simulation study to assess impact of the CR hits for the LiteBIRD detectors. Here, we describe procedures to make maps and power spectra from the simulated time-ordered data, and present initial results. Our initial estimate is that $C_l^{BB}$ by CR is $\sim 2 \times 10^{-6}~\mu$K$_{\mathrm{CMB}}^{2}$ in a one-year observation with 12 detectors assuming that the noise is 1~aW/$\sqrt{\mathrm{Hz}}$ for the differential mode of two detectors constituting a polarization pair.