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First release of LiteBIRD simulations from an end-to-end pipeline

M. Bortolami, N. Raffuzzi, L. Pagano, G. Puglisi, A. Anand, A. J. Banday, P. Campeti, G. Galloni, A. I. Lonappan, M. Monelli, M. Tomasi, G. Weymann-Despres, D. Adak, E. Allys, J. Aumont, R. Aurvik, C. Baccigalupi, M. Ballardini, R. B. Barreiro, N. Bartolo, S. Basak, M. Bersanelli, A. Besnard, T. Brinckmann, E. Calabrese, E. Carinos, A. Carones, F. J. Casas, K. Cheung, M. Citran, L. Clermont, F. Columbro, G. Coppi, A. Coppolecchia, F. Cuttaia, P. Dal Bo, P. de Bernardis, E. de la Hoz, M. De Lucia, S. Della Torre, P. Diego-Palazuelos, H. K. Eriksen, T. Essinger-Hileman, C. Franceschet, U. Fuskeland, M. Galloway, M. Gerbino, M. Gervasi, T. Ghigna, S. Giardiello, C. Gimeno-Amo, E. Gjerløw, A. Gruppuso, M. Hazumi, S. Henrot-Versillé, L. T. Hergt, E. Hivon, B. Jost, K. Kohri, L. Lamagna, T. Lari, M. Lattanzi, C. Leloup, F. Levrier, M. López-Caniego, G. Luzzi, J. Macias-Perez, B. Maffei, E. Martínez-González, S. Masi, S. Matarrese, T. Matsumura, S. Micheli, L. Montier, G. Morgante, L. Mousset, R. Nagata, T. Namikawa, A. Novelli, F. Noviello, I. Obata, A. Occhiuzzi, A. Paiella, D. Paoletti, G. Pascual-Cisneros, F. Piacentini, M. Pinchera, G. Polenta, L. Porcelli, M. Remazeilles, A. Ritacco, A. Rizzieri, J. A. Rubiño-Martín, M. Ruiz-Granda, J. Sanghavi, V. Sauvage, M. Shiraishi, G. Signorelli, S. L. Stever, R. M. Sullivan, Y. Takase, K. Tassis, L. Terenzi, M. Tristram, L. Vacher, B. van Tent, P. Vielva, I. K. Wehus, M. Zannoni, Y. Zhou

TL;DR

LiteBIRD targets detection of CMB $B$-modes with a total error on $r$ of $δr \sim 0.001$. The paper presents the first official end-to-end LiteBIRD simulations using the LiteBIRD Simulation Framework, generating 500 full-sky maps at $N_{\mathrm{side}}=512$ and one year of TOD for about one-third of detectors, including CMB and foregrounds, instrumental noise with $1/f$ components, and a CMB dipole. Validation shows that the Half-Wave Plate (HWP) effectively suppresses $1/f$ noise in polarization and that the pipeline’s outputs match the input maps within noise realizations, with comprehensive covariance and power-spectrum analyses. The work demonstrates a scalable path toward full focal-plane, multi-year simulations and sets the stage for incorporating additional instrumental systematics in future releases, with broad utility for pipeline development, validation, and SEO-ready summaries.

Abstract

The LiteBIRD satellite mission aims at detecting Cosmic Microwave Background $B$ modes with unprecedented precision, targeting a total error on the tensor-to-scalar ratio $r$ of $δr \sim 0.001$. Operating from the L2 Lagrangian point of the Sun-Earth system, LiteBIRD will survey the full sky across 15 frequency bands (34 to 448 GHz) for 3 years.The current LiteBIRD baseline configuration employs 4508 detectors sampling at 19.1 Hz to achieve an effective polarization sensitivity of $ 2 μ\mathrm{K-arcmin}$ and an angular resolution of 31 arcmin (at 140 GHz).We describe the first release of the official LiteBIRD simulations, realized with a new simulation pipeline developed using the LiteBIRD Simulation Framework, see https://github.com/litebird/litebird_sim . This pipeline generates 500 full-sky simulated maps at a Healpix resolution of nside=512. The simulations include also one year of Time Ordered Data for approximately one-third of LiteBIRD's total detectors.

First release of LiteBIRD simulations from an end-to-end pipeline

TL;DR

LiteBIRD targets detection of CMB -modes with a total error on of . The paper presents the first official end-to-end LiteBIRD simulations using the LiteBIRD Simulation Framework, generating 500 full-sky maps at and one year of TOD for about one-third of detectors, including CMB and foregrounds, instrumental noise with components, and a CMB dipole. Validation shows that the Half-Wave Plate (HWP) effectively suppresses noise in polarization and that the pipeline’s outputs match the input maps within noise realizations, with comprehensive covariance and power-spectrum analyses. The work demonstrates a scalable path toward full focal-plane, multi-year simulations and sets the stage for incorporating additional instrumental systematics in future releases, with broad utility for pipeline development, validation, and SEO-ready summaries.

Abstract

The LiteBIRD satellite mission aims at detecting Cosmic Microwave Background modes with unprecedented precision, targeting a total error on the tensor-to-scalar ratio of . Operating from the L2 Lagrangian point of the Sun-Earth system, LiteBIRD will survey the full sky across 15 frequency bands (34 to 448 GHz) for 3 years.The current LiteBIRD baseline configuration employs 4508 detectors sampling at 19.1 Hz to achieve an effective polarization sensitivity of and an angular resolution of 31 arcmin (at 140 GHz).We describe the first release of the official LiteBIRD simulations, realized with a new simulation pipeline developed using the LiteBIRD Simulation Framework, see https://github.com/litebird/litebird_sim . This pipeline generates 500 full-sky simulated maps at a Healpix resolution of nside=512. The simulations include also one year of Time Ordered Data for approximately one-third of LiteBIRD's total detectors.

Paper Structure

This paper contains 12 sections, 8 equations, 11 figures, 3 tables.

Table of Contents

  1. Introduction
  2. Instrument model
  3. Input sky maps
  4. Simulation pipeline
  5. Results and validation
  6. TOD
  7. Covariance matrices
  8. Power spectra
  9. Computational cost
  10. Conclusions
  11. Products of the pipeline
  12. Comparison between input and output maps

Figures (11)

  • Figure 1: Detectors present in LiteBIRD's LFT (left), MFT (middle) and HFT (right). The colors highlight wafers with the same frequency. The black stars indicate the selected pixels.
  • Figure 2: Cartoon representation of the LiteBIRD satellite and its scanning parameters. $\alpha=45^\circ$ is the angle between the spin axis and the Sun--Earth axis, $\beta=50^\circ$ is the angle separating the boresight from the spin axis. A summary of the scanning parameters is in Table \ref{['tab:scanning_parameters']}.
  • Figure 3: Coadded input maps in Galactic coordinates. $T$ (left column), $Q$ (middle column), $U$ (right column) coadded input maps of CMB and foregrounds for the first simulation. First row: L1-040 channel of LFT. Second row: M1-140 channel of MFT. Third row: H3-402 channel of HFT.
  • Figure 4: Top panels: the CMB power spectra for temperature and polarization are compared to the noise spectra in the absence of a half-wave plate (HWP). The fiducial signal is derived from the best-fit cosmological parameters of the Planck 2018 data planck2016-l06, obtained from the TT, TE, EE + lowE + lensing analysis. The noise power spectra are computed as the spectrum of the difference between the binned output and input maps, inversely coadded across all channels and averaged over the first 50 simulations. The various curves represent different levels of $1/f$ noise knee frequencies, along with the white noise-only baseline. For polarization (without HWP), the noise is estimated by scaling the temperature noise by a factor of 2. This scaling is consistent with the elevated noise levels observed in polarization, illustrated in Figure \ref{['fig:covs']} and by the green curves in Figure \ref{['fig:covs_validation_test']}. Bottom panels: LiteBIRD high signal-to-noise ratio is evident across all $1/f$ noise levels. Cosmic variance dominates the very low-$\ell$ regime, and the signal remains robust up to multipoles of approximately $\ell \simeq 1100$ (TT), $\ell \simeq 900$ (EE), and $\ell \simeq 500$ (BB).
  • Figure 5: Sum of TODs of CMB, foregrounds, dipole, white noise and $1/f$ noise with $f_{\rm knee}=30\ \mathrm{mHz}$ for three different detectors and for the first simulation. The numbers in the legend refer to the detectors number as explained in the text, while the T (B) letter refer to the detector being top (bottom). Left panel: L1-040 channel of LFT. Right panel: M1-140 channel of MFT.
  • ...and 6 more figures