Explanipedia

A simulation framework for the LiteBIRD instruments Open

M. Tomasi, L. Pagano, A. Anand, C. Baccigalupi, A. J. Banday , et al. · 2025

LiteBIRD, the Lite (Light) satellite for the study of B-mode polarization and Inflation from cosmic background Radiation Detection, is a space mission focused on primordial cosmology and fundamental physics. In this paper, we present the L…

A simulation framework for the <i>LiteBIRD</i> instruments Open

M Tomasi, L. Pagano, Anil C. Anand, C Baccigalupi, A. J. Banday , et al. · 2025

LiteBIRD , the Lite (Light) satellite for the study of B-mode polarization and Inflation from cosmic background Radiation Detection, is a space mission focused on primordial cosmology and fundamental physics. In this paper, we present the …

LiteBIRD science goals and forecasts: improved full-sky reconstruction of the gravitational lensing potential through the combination of Planck and LiteBIRD data Open

M. Ruiz-Granda, P. Diego-Palazuelos, C. Gimeno-Amo, P. Vielva, A.I. Lonappan , et al. · 2025

Cosmic microwave background (CMB) photons are deflected by large-scale structure through gravitational lensing. This secondary effect introduces higher-order correlations in CMB anisotropies, which are used to reconstruct lensing deflectio…

First release of <i>LiteBIRD</i> simulations from an end-to-end pipeline Open

M. Bortolami, N. Raffuzzi, L. Pagano, Giuseppe Puglisi, A. J. Banday , et al. · 2025

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 ∼ 0.001. Operating from the L2 Lagrangian point of the Sun-Ear…

Requirements on bandpass resolution and measurement precision for LiteBIRD Open

S. Giardiello, A. Carones, T. Ghigna, L. Pagano, F. Piacentini , et al. · 2025

Systematic effects can hinder the sought-after detection of primordial gravitational waves, impacting the reconstruction of the B -mode polarization signal which they generate in the cosmic microwave background (CMB). In this work, we stud…

Adjusting optical cavity birefringence with wavelength tunable laser for axion searches Open

Hinata Takidera, Hiroki Fujimoto, Yuka Oshima, Satoru Takano, K. Komori , et al. · 2025

Axions have attracted attention as promising candidates for dark matter (DM). Although axions have been intensively searched for, they have not been observed yet. Recently, novel experiments to search for axion DM have been proposed that u…

LiteBIRD Science Goals and Forecasts. $E$-mode Anomalies Open

A. J. Banday, C. Gimeno-Amo, P. Diego-Palazuelos, E. de la Hoz, A. Gruppuso , et al. · 2025

Various so-called anomalies have been found in both the WMAP and Planck cosmic microwave background (CMB) temperature data that exert a mild tension against the highly successful best-fit 6 parameter cosmological model, potentially providi…

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

M. Bortolami, N. Raffuzzi, L. Pagano, Giuseppe Puglisi, Ashish Anand , et al. · 2025

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 th…

On the computational feasibility of Bayesian end-to-end analysis of LiteBIRD simulations within Cosmoglobe Open

R Aurvik, M. Galloway, E. Gjerløw, U Fuskeland, A. Basyrov , et al. · 2025

We assess the computational feasibility of end-to-end Bayesian analysis of the JAXA-led LiteBIRD experiment by analysing simulated time ordered data (TOD) for a subset of detectors through the Cosmoglobe and Commander3 framework. The data …

LiteBIRD science goals and forecasts: constraining isotropic cosmic birefringence Open

E. de la Hoz, P. Diego-Palazuelos, Josquin Errard, A. Gruppuso, Baptiste Jost , et al. · 2025

Cosmic birefringence (CB) is the rotation of the photons' linear polarisation plane during propagation. Such an effect is a tracer of parity-violating extensions of standard electromagnetism and would probe the existence of a new cosmologi…

Searches for ultralight vector and axion dark matter with KAGRA Open

Yuta Michimura, T. Fujimori, Hiroki Fujimoto, Tomohiro Fujita, Kentaro Komori , et al. · 2025

We have proposed using laser interferometric gravitational wave detectors to search for ultralight vector and axion dark matter. Vector dark matter can be probed through oscillating forces on suspended mirrors, while axion dark matter can …

Requirements on the gain calibration for LiteBIRD polarisation data with blind component separation Open

F. Carralot, A. Carones, N. Krachmalnicoff, T. Ghigna, A. Novelli , et al. · 2025

The detection of primordial B modes of the cosmic microwave background (CMB) could provide information about the early stages of the Universe's evolution. The faintness of this signal requires exquisite calibration accuracy and control of …

Requirements on the gain calibration for LiteBIRD polarisation data with blind component separation Open

F. Carralot, A. Carones, N Krachmalnicoff, T. Ghigna, Andrea Novelli , et al. · 2024

Future cosmic microwave background (CMB) experiments are primarily targeting a detection of the primordial $B$-mode polarisation. The faintness of this signal requires exquisite control of systematic effects which may bias the measurements…

Constraining Ultralight ALP Dark Matter in Light of Cosmic Birefringence Open

Dongdong Zhang, Elisa G. M. Ferreira, Ippei Obata, Toshiya Namikawa · 2024

Cosmic birefringence, the observed rotation of the polarization plane of the cosmic microwave background (CMB), serves as a compelling probe for parity-violating physics beyond the Standard Model. This study explores the potential of ultra…

Axion-gauge dynamics during inflation as the origin of pulsar timing array signals and primordial black holes Open

Caner Ünal, Alexandros Papageorgiou, Ippei Obata · 2024

We demonstrate that the recently announced signal for a stochastic gravitational wave background (SGWB) from pulsar timing array (PTA) observations, if attributed to new physics, is compatible with primordial GW production due to axion-gau…

LiteBIRD science goals and forecasts: primordial magnetic fields Open

D. Paoletti, J. A. Rubiño-Martín, Maresuke Shiraishi, D. Molinari, Jens Chluba , et al. · 2024

We present detailed forecasts for the constraints on the characteristics of primordial magnetic fields (PMFs) generated prior to recombination that will be obtained with the LiteBIRD satellite. The constraints are driven by some of the mai…

Impact of beam far side-lobe knowledge in the presence of foregrounds for LiteBIRD Open

C. Leloup, G. Patanchon, Josquin Errard, C. Franceschet, Jon E. Gudmundsson , et al. · 2024

We present a study of the impact of a beam far side-lobe lack of knowledge on the measurement of the Cosmic Microwave Background B -mode signal at large scale. Beam far side-lobes induce a mismatch in the transfer function of Galactic fore…

LiteBIRD science goals and forecasts: a full-sky measurement of gravitational lensing of the CMB Open

A.I. Lonappan, Toshiya Namikawa, G. Piccirilli, P. Diego-Palazuelos, M. Ruiz-Granda , et al. · 2024

We explore the capability of measuring lensing signals in LiteBIRD full-sky polarization maps. With a 30 arcmin beam width and an impressively low polarization noise of 2.16 μ K-arcmin, LiteBIRD will be able to measure the full-sky polariz…

LiteBIRD science goals and forecasts: improving sensitivity to inflationary gravitational waves with multitracer delensing Open

Toshiya Namikawa, A.I. Lonappan, C. Baccigalupi, N. Bartolo, D. Beck , et al. · 2024

We estimate the efficiency of mitigating the lensing B -mode polarization, the so-called delensing, for the LiteBIRD experiment with multiple external data sets of lensing-mass tracers. The current best bound on the tensor-to-scalar ratio,…

LiteBIRD science goals and forecasts. A case study of the origin of primordial gravitational waves using large-scale CMB polarization Open

P. Campeti, Eiichiro Komatsu, C. Baccigalupi, M. Ballardini, N. Bartolo , et al. · 2024

We study the possibility of using the LiteBIRD satellite B -mode survey to constrain models of inflation producing specific features in CMB angular power spectra. We explore a particular model example, i.e. spectator axion-SU(2) gauge fiel…

$nπ$ phase ambiguity of cosmic birefringence Open

Fumihiro Naokawa, Toshiya Namikawa, Kai Murai, Ippei Obata, Kohei Kamada · 2024

We point out that the rotation angle $β$ of cosmic birefringence, which is a recently reported parity-violating signal in the cosmic microwave background (CMB), has a phase ambiguity of $nπ\,(n\in\mathbb{Z})$. This ambiguity has a signific…

Testing Gravity with Frequency-Dependent Overlap Reduction Function in Pulsar Timing Array Open

Qiuyue Liang, Ippei Obata, Misao Sasaki · 2024

The positive evidence of a nano-hertz gravitational wave background recently found by several pulsar timing array (PTA) collaborations opened up a window to test modified gravity theories in a unique frequency band in parallel to other gra…

Parity-violating scalar trispectrum from a rolling axion during inflation Open

Tomohiro Fujita, Tomoaki Murata, Ippei Obata, Maresuke Shiraishi · 2024

We study a mechanism of generating the trispectrum (4-point correlation) of curvature perturbation through the dynamics of a spectator axion field and U(1) gauge field during inflation. Owing to the Chern-Simons coupling, only one helicity…

LiteBIRD Science Goals and Forecasts: Primordial Magnetic Fields Open

D. Paoletti, J. A. Rubiño-Martín, Maresuke Shiraishi, D. Molinari, Jens Chluba , et al. · 2024

We present detailed forecasts for the constraints on primordial magnetic fields (PMFs) that will be obtained with the LiteBIRD satellite. The constraints are driven by the effects of PMFs on the CMB anisotropies: the gravitational effects …

Can we explain cosmic birefringence without a new light field beyond Standard Model? Open

Yuichiro Nakai, Ryo Namba, Ippei Obata, Yu-Cheng Qiu, Ryo Saito · 2024

A bstract The recent analysis of the Planck 2018 polarization data shows a nonzero isotropic cosmic birefringence (ICB) that is not explained within the ΛCDM paradigm. We then explore the question of whether the nonzero ICB is interpreted …

Axionic defects in the CMB: birefringence and gravitational waves Open

Ricardo Z. Ferreira, Silvia Gasparotto, Takashi Hiramatsu, Ippei Obata, Oriol Pujolàs · 2023

The evidence for a non-vanishing isotropic cosmic birefringence in recent analyses of the CMB data provides a tantalizing hint for new physics. Domain wall (DW) networks have recently been shown to generate an isotropic birefringence signa…

Impact of beam far side-lobe knowledge in the presence of foregrounds for LiteBIRD Open

C. Leloup, G. Patanchon, J. Errard, C. Franceschet, Jon E. Gudmundsson , et al. · 2023

We present a study of the impact of an uncertainty in the beam far side-lobe knowledge on the measurement of the Cosmic Microwave Background $B$-mode signal at large scale. It is expected to be one of the main source of systematic effects …

LiteBIRD Science Goals and Forecasts: Improving Sensitivity to Inflationary Gravitational Waves with Multitracer Delensing Open

Toshiya Namikawa, A.I. Lonappan, C. Baccigalupi, N. Bartolo, D. Beck , et al. · 2023

We estimate the efficiency of mitigating the lensing $B$-mode polarization, the so-called delensing, for the $LiteBIRD$ experiment with multiple external data sets of lensing-mass tracers. The current best bound on the tensor-to-scalar rat…

LiteBIRD Science Goals and Forecasts: A full-sky measurement of gravitational lensing of the CMB Open

A.I. Lonappan, Toshiya Namikawa, G. Piccirilli, P. Diego-Palazuelos, M. Ruiz-Granda , et al. · 2023

We explore the capability of measuring lensing signals in $LiteBIRD$ full-sky polarization maps. With a $30$ arcmin beam width and an impressively low polarization noise of $2.16\,μ$K-arcmin, $LiteBIRD$ will be able to measure the full-sky…

LiteBIRD Science Goals and Forecasts. A Case Study of the Origin of Primordial Gravitational Waves using Large-Scale CMB Polarization Open

P. Campeti, Eiichiro Komatsu, C. Baccigalupi, M. Ballardini, N. Bartolo , et al. · 2023

We study the possibility of using the $LiteBIRD$ satellite $B$-mode survey to constrain models of inflation producing specific features in CMB angular power spectra. We explore a particular model example, i.e. spectator axion-SU(2) gauge f…

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