Journal articles: 'LiteBIRD'

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Remazeilles, M., M. Douspis, J. A. Rubiño-Martín, et al. "LiteBIRD science goals and forecasts. Mapping the hot gas in the Universe." Journal of Cosmology and Astroparticle Physics 2024, no. 12 (2024): 026. https://doi.org/10.1088/1475-7516/2024/12/026.

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Abstract We assess the capabilities of the LiteBIRD mission to map the hot gas distribution in the Universe through the thermal Sunyaev-Zeldovich (SZ) effect. Our analysis relies on comprehensive simulations incorporating various sources of Galactic and extragalactic foreground emission, while accounting for the specific instrumental characteristics of the LiteBIRD mission, such as detector sensitivities, frequency-dependent beam convolution, inhomogeneous sky scanning, and 1/f noise. We implement a tailored component-separation pipeline to map the thermal SZ Compton y-parameter over 98% of the sky. Despite lower angular resolution for galaxy cluster science, LiteBIRD provides full-sky coverage and, compared to the Planck satellite, enhanced sensitivity, as well as more frequency bands to enable the construction of an all-sky thermal SZ y-map, with reduced foreground contamination at large and intermediate angular scales. By combining LiteBIRD and Planck channels in the component-separation pipeline, we also obtain an optimal y-map that leverages the advantages of both experiments, with the higher angular resolution of the Planck channels enabling the recovery of compact clusters beyond the LiteBIRD beam limitations, and the numerous sensitive LiteBIRD channels further mitigating foregrounds. The added value of LiteBIRD is highlighted through the examination of maps, power spectra, and one-point statistics of the various sky components. After component separation, the 1/f noise from LiteBIRD's intensity channels is effectively mitigated below the level of the thermal SZ signal at all multipoles. Cosmological constraints on S 8 = σ 8 (Ωm /0.3)0.5 obtained from the LiteBIRD-Planck combined y-map power spectrum exhibits a 15 % reduction in uncertainty compared to constraints derived from Planck alone. This improvement can be attributed to the increased portion of uncontaminated sky available in the LiteBIRD-Planck combined y-map.

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Ishino, Hirokazu. "LiteBIRD." International Journal of Modern Physics: Conference Series 43 (January 2016): 1660192. http://dx.doi.org/10.1142/s2010194516601927.

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We present LiteBIRD, a satellite project dedicated for the detection of the CMB B-mode polarization. The purpose of LiteBIRD is to measure the tensor-to-scalar ratio [Formula: see text] with a precision of [Formula: see text] to test large-single-field slow-roll inflation models by scanning all the sky area for three years at the sun-earth L2 with the sensitivity of 3.2[Formula: see text]K⋅arcmin. We report an overview and the status of the project, including the ongoing detector and systematic studies.

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Paoletti, D., J. A. Rubino-Martin, M. Shiraishi, et al. "LiteBIRD science goals and forecasts: primordial magnetic fields." Journal of Cosmology and Astroparticle Physics 2024, no. 07 (2024): 086. http://dx.doi.org/10.1088/1475-7516/2024/07/086.

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Abstract 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 main physical effects of PMFs on the CMB anisotropies: the gravitational effects of magnetically-induced perturbations; the effects on the thermal and ionization history of the Universe; the Faraday rotation imprint on the CMB polarization spectra; and the non-Gaussianities induced in polarization anisotropies. LiteBIRD represents a sensitive probe for PMFs. We explore different levels of complexity, for LiteBIRD data and PMF configurations, accounting for possible degeneracies with primordial gravitational waves from inflation. By exploiting all the physical effects, LiteBIRD will be able to improve the current limit on PMFs at intermediate and large scales coming from Planck. In particular, thanks to its accurate B-mode polarization measurement, LiteBIRD will improve the constraints on infrared configurations for the gravitational effect, giving B n B=-2.9 1 Mpc< 0.8 nG at 95% C.L., potentially opening the possibility to detect nanogauss fields with high significance. We also observe a significant improvement in the limits when marginalized over the spectral index, B n Bmarg 1 Mpc< 2.2 nG at 95 % C.L. From the thermal history effect, which relies mainly on E-mode polarization data, we obtain a significant improvement for all PMF configurations, with the marginalized case, √⟨B 2⟩marg<0.50 nG at 95 % C.L. Faraday rotation constraints will take advantage of the wide frequency coverage of LiteBIRD and the high sensitivity in B modes, improving the limits by orders of magnitude with respect to current results, B n B=-2.9 1 Mpc < 3.2 nG at 95 % C.L. Finally, non-Gaussianities of the B-mode polarization can probe PMFs at the level of 1 nG, again significantly improving the current bounds from Planck. Altogether our forecasts represent a broad collection of complementary probes based on widely tested methodologies, providing conservative limits on PMF characteristics that will be achieved with the LiteBIRD satellite.

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Namikawa, T., A. I. Lonappan, C. Baccigalupi, et al. "LiteBIRD science goals and forecasts: improving sensitivity to inflationary gravitational waves with multitracer delensing." Journal of Cosmology and Astroparticle Physics 2024, no. 06 (2024): 010. http://dx.doi.org/10.1088/1475-7516/2024/06/010.

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Abstract 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, r, is limited by lensing rather than Galactic foregrounds. Delensing will be a critical step to improve sensitivity to r as measurements of r become more and more limited by lensing. In this paper, we extend the analysis of the recent LiteBIRD forecast paper to include multiple mass tracers, i.e., the CMB lensing maps from LiteBIRD and CMB-S4-like experiment, cosmic infrared background, and galaxy number density from Euclid- and LSST-like survey. We find that multi-tracer delensing will further improve the constraint on r by about 20%. In LiteBIRD, the residual Galactic foregrounds also significantly contribute to uncertainties of the B-modes, and delensing becomes more important if the residual foregrounds are further reduced by an improved component separation method.

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Matsumura, T., Y. Akiba, J. Borrill, et al. "Mission Design of LiteBIRD." Journal of Low Temperature Physics 176, no. 5-6 (2014): 733–40. http://dx.doi.org/10.1007/s10909-013-0996-1.

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Campeti, P., E. Komatsu, C. Baccigalupi, et al. "LiteBIRD science goals and forecasts. A case study of the origin of primordial gravitational waves using large-scale CMB polarization." Journal of Cosmology and Astroparticle Physics 2024, no. 06 (2024): 008. http://dx.doi.org/10.1088/1475-7516/2024/06/008.

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Abstract 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 field inflation. This model can source parity-violating gravitational waves from the amplification of gauge field fluctuations driven by a pseudoscalar “axionlike” field, rolling for a few e-folds during inflation. The sourced gravitational waves can exceed the vacuum contribution at reionization bump scales by about an order of magnitude and can be comparable to the vacuum contribution at recombination bump scales. We argue that a satellite mission with full sky coverage and access to the reionization bump scales is necessary to understand the origin of the primordial gravitational wave signal and distinguish among two production mechanisms: quantum vacuum fluctuations of spacetime and matter sources during inflation. We present the expected constraints on model parameters from LiteBIRD satellite simulations, which complement and expand previous studies in the literature. We find that LiteBIRD will be able to exclude with high significance standard single-field slow-roll models, such as the Starobinsky model, if the true model is the axion-SU(2) model with a feature at CMB scales. We further investigate the possibility of using the parity-violating signature of the model, such as the TB and EB angular power spectra, to disentangle it from the standard single-field slow-roll scenario. We find that most of the discriminating power of LiteBIRD will reside in BB angular power spectra rather than in TB and EB correlations.

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Jinno, Ryusuke, Kazunori Kohri, Takeo Moroi, Tomo Takahashi, and Masashi Hazumi. "Testing multi-field inflation with LiteBIRD." Journal of Cosmology and Astroparticle Physics 2024, no. 03 (2024): 011. http://dx.doi.org/10.1088/1475-7516/2024/03/011.

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Abstract We investigate expected constraints on the primordial tensor power spectrum from the future cosmic microwave background polarization experiment LiteBIRD as a test of multi-field inflation, where we specifically consider spectator models as representative examples. We argue that the measurements of the tensor-to-scalar ratio and the tensor spectral index, in combination with the constraints on the scalar spectral index from the Planck observation, are useful in testing multi-field inflation models. We also discuss implications for multi-field inflationary model building.

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Lonappan, A. I., T. Namikawa, G. Piccirilli, et al. "LiteBIRD science goals and forecasts: a full-sky measurement of gravitational lensing of the CMB." Journal of Cosmology and Astroparticle Physics 2024, no. 06 (2024): 009. http://dx.doi.org/10.1088/1475-7516/2024/06/009.

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Abstract 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 μK-arcmin, LiteBIRD will be able to measure the full-sky polarization of the cosmic microwave background (CMB) very precisely. This unique sensitivity also enables the reconstruction of a nearly full-sky lensing map using only polarization data, even considering its limited capability to capture small-scale CMB anisotropies. In this paper, we investigate the ability to construct a full-sky lensing measurement in the presence of Galactic foregrounds, finding that several possible biases from Galactic foregrounds should be negligible after component separation by harmonic-space internal linear combination. We find that the signal-to-noise ratio of the lensing is approximately 40 using only polarization data measured over 80% of the sky. This achievement is comparable to Planck's recent lensing measurement with both temperature and polarization and represents a four-fold improvement over Planck's polarization-only lensing measurement. The LiteBIRD lensing map will complement the Planck lensing map and provide several opportunities for cross-correlation science, especially in the northern hemisphere.

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dos Santos, F. B. M., G. Rodrigues, R. de Souza, and J. S. Alcaniz. "Stage IV CMB forecasts for warm inflation." Journal of Cosmology and Astroparticle Physics 2025, no. 03 (2025): 062. https://doi.org/10.1088/1475-7516/2025/03/062.

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Abstract We report forecast constraints on warm inflation in the light of future cosmic microwave background (CMB) surveys, with data expected to be available in the coming decade. These observations could finally give us the missing information necessary to unveil the production of gravitational waves during inflation, reflected by the detection of a non-zero tensor-to-scalar ratio crucial to the B-mode power spectrum of the CMB. We consider the impact of three future surveys, namely the CMB-S4, Simons Observatory, and the space-borne LiteBIRD, in restricting the parameter space of four typical warm inflationary models in the context of a quartic potential, which is well motivated theoretically. We find that all three surveys significantly improve the models' parameter space, compared to recent results obtained with current Planck+BICEP/Keck Array data. Moreover, the combination of ground-based and space-borne (SO+LiteBIRD and CMB-S4+LiteBIRD) surveys tightens the constraints so that we expect to distinguish even better warm inflation scenarios. This result becomes clear when we compare the models' predictions with a ΛCDM+r forecast, compatible with r = 0, in which one of them already becomes excluded by data.

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Remazeilles, Mathieu, Andrea Ravenni та Jens Chluba. "Leverage on small-scale primordial non-Gaussianity through cross-correlations between CMB E-mode and μ-distortion anisotropies". Monthly Notices of the Royal Astronomical Society 512, № 1 (2022): 455–70. http://dx.doi.org/10.1093/mnras/stac519.

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ABSTRACT Multifield inflation models and non-Bunch–Davies vacuum initial conditions both predict sizeable non-Gaussian primordial perturbations and anisotropic μ-type spectral distortions of the cosmic microwave background (CMB) blackbody. While CMB anisotropies allow us to probe non-Gaussianity at wavenumbers $k\simeq 0.05\, {\rm Mpc^{-1}}$, μ-distortion anisotropies are related to non-Gaussianity of primordial perturbation modes with much larger wavenumbers, $k\simeq 740\, {\rm Mpc^{-1}}$. Through cross-correlations between CMB and μ-distortion anisotropies, one can therefore shed light on the aforementioned inflation models. We investigate the ability of a future CMB satellite imager like LiteBIRD to measure μT and μE cross-power spectra between anisotropic μ-distortions and CMB temperature and E-mode polarization anisotropies in the presence of foregrounds, and derive LiteBIRD forecasts on ${f_{\rm NL}^\mu (k\simeq 740\, {\rm Mpc^{-1}})}$. We show that μE cross-correlations with CMB polarization provide more constraining power on $f_{\rm NL}^\mu$ than μT cross-correlations in the presence of foregrounds, and the joint combination of μT and μE observables adds further leverage to the detection of small-scale primordial non-Gaussianity. For multifield inflation, we find that LiteBIRD would detect ${f_{\rm NL}^\mu }=4500$ at 5σ significance after foreground removal, and achieve a minimum error of ${\sigma (f_{\rm NL}^\mu =0) \simeq 800}$ at 68 per cent CL by combining CMB temperature and polarization. Due to the huge dynamic range of wavenumbers between CMB and μ-distortion anisotropies, such large $f^\mu _{\rm NL}$ values would still be consistent with current CMB constraints in the case of very mild scale dependence of primordial non-Gaussianity. Anisotropic spectral distortions thus provide a new path, complementary to CMB B-modes, to probe inflation with LiteBIRD.

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Matsumura, T., Y. Akiba, K. Arnold, et al. "LiteBIRD: Mission Overview and Focal Plane Layout." Journal of Low Temperature Physics 184, no. 3-4 (2016): 824–31. http://dx.doi.org/10.1007/s10909-016-1542-8.

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Suzuki, A., P. A. R. Ade, Y. Akiba, et al. "The LiteBIRD Satellite Mission: Sub-Kelvin Instrument." Journal of Low Temperature Physics 193, no. 5-6 (2018): 1048–56. http://dx.doi.org/10.1007/s10909-018-1947-7.

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Drewes, Marco, Lei Ming, and Isabel Oldengott. "LiteBIRD and CMB-S4 sensitivities to reheating in plateau models of inflation." Journal of Cosmology and Astroparticle Physics 2024, no. 05 (2024): 081. http://dx.doi.org/10.1088/1475-7516/2024/05/081.

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Abstract We study the sensitivity of LiteBIRD and CMB-S4 to the reheating temperature and the inflaton coupling in three types of plateau-potential models of inflation, namely mutated hilltop inflation, radion gauge inflation, and α-attractor T models. We first find relations between model parameters and CMB observables in all models. We then perform Monte Carlo Markov Chain based forecasts to quantify the information gain on the reheating temperature, the inflaton coupling, and the scale of inflation that can be achieved with LiteBIRD and CMB-S4, assuming a fiducial tensor-to-scalar ratio r̅ ∼ 0.02 and neglecting foreground contamination of the B-mode polarization spectrum. We compare the results of the forecasts to those obtained from a recently proposed simple analytic method. We find that both LiteBIRD and CMB-S4 can simultaneously constrain the scale of inflation and the reheating temperature in all three types of models. They can for the first time obtain both an upper and lower bound on the latter, comprising the first ever measurement of the big bang temperature. In the mutated hilltop inflation and radion gauge inflation models this can be translated into a measurement of the inflaton coupling in parts of the parameter space. Constraining this microphysical parameter will help to understand how these models of inflation may be embedded into a more fundamental theory of particle physics.

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Giardiello, S., M. Gerbino, L. Pagano, et al. "Detailed study of HWP non-idealities and their impact on future measurements of CMB polarization anisotropies from space." Astronomy & Astrophysics 658 (January 25, 2022): A15. http://dx.doi.org/10.1051/0004-6361/202141619.

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We study the propagation of a specific class of instrumental systematics to the reconstruction of the B-mode power spectrum of the cosmic microwave background (CMB). We focus on the non-idealities of the half-wave plate (HWP), a polarization modulator that is to be deployed by future CMB experiments, such as the phase-A satellite mission LiteBIRD. We study the effects of non-ideal HWP properties, such as transmittance, phase shift, and cross-polarization. To this end, we developed a simple, yet stand-alone end-to-end simulation pipeline adapted to LiteBIRD. We analyzed the effects of a possible mismatch between the measured frequency profiles of HWP properties (used in the mapmaking stage of the pipeline) and the actual profiles (used in the sky-scanning step). We simulated single-frequency, CMB-only observations to emphasize the effects of non-idealities on the BB power spectrum. We also considered multi-frequency observations to account for the frequency dependence of HWP properties and the contribution of foreground emission. We quantified the systematic effects in terms of a bias Δr on the tensor-to-scalar ratio, r, with respect to the ideal case without systematic effects. We derived the accuracy requirements on the measurements of HWP properties by requiring Δr < 10−5 (1% of the expected LiteBIRD sensitivity on r). Our analysis is introduced by a detailed presentation of the mathematical formalism employed in this work, including the use of the Jones and Mueller matrix representations.

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Carralot, F., A. Carones, N. Krachmalnicoff, et al. "Requirements on the gain calibration for LiteBIRD polarisation data with blind component separation." Journal of Cosmology and Astroparticle Physics 2025, no. 01 (2025): 019. https://doi.org/10.1088/1475-7516/2025/01/019.

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Abstract 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 instrumental systematic effects which otherwise could bias the measurements. In this work, we study the impact of an imperfect relative polarisation gain calibration on the recovered value of the tensor-to-scalar ratio r for the LiteBIRD experiment, through the application of the blind Needlet Internal Linear Combination (NILC) foreground-cleaning method. We derive requirements on the relative calibration accuracy of the overall polarisation gain (Δgν ) for each LiteBIRD frequency channel. Our results show that minimum variance techniques, as NILC, are less sensitive to systematic gain calibration uncertainties compared to a parametric approach, if the latter is not equipped with a proper modelling of these instrumental effects. In this study, the most stringent requirements are found in the channels where the CMB signal is relatively brighter, with the tightest constraints at 166 GHz (Δgν ≈ 0.16%). This differs from the outcome of an analogous analysis performed with a parametric method, where the tightest requirements are obtained for the foreground-dominated channels. Gain calibration uncertainties, corresponding to the derived requirements, are then simultaneously propagated into all frequency channels. By doing so, we find that the overall impact on estimated r is lower than the total gain systematic budget for LiteBIRD approximately by a factor 5, due to the correlations of the impacts of gain calibration uncertainties in different frequency channels. In order to decouple the systematic effect from the specific choice of the model, we derive the requirements assuming constant spectral parameters for the foreground emission. To assess the robustness of the obtained results against more realistic scenarios, we repeat the analysis assuming sky models of intermediate and high complexity. In these further cases, we adopt an optimised NILC pipeline, called the Multi-Clustering NILC (MC-NILC). We find that the impact of gain calibration uncertainties on r is lower than the LiteBIRD gain systematics budget for the intermediate-complexity sky model. For the high-complexity case, instead, it would be necessary to tighten the requirements by a factor 1.8.

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Takase, Y., L. Vacher, H. Ishino, et al. "Multi-dimensional optimisation of the scanning strategy for the LiteBIRD space mission." Journal of Cosmology and Astroparticle Physics 2024, no. 12 (2024): 036. https://doi.org/10.1088/1475-7516/2024/12/036.

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Abstract Large angular scale surveys in the absence of atmosphere are essential for measuring the primordial B-mode power spectrum of the Cosmic Microwave Background (CMB). Since this proposed measurement is about three to four orders of magnitude fainter than the temperature anisotropies of the CMB, in-flight calibration of the instruments and active suppression of systematic effects are crucial. We investigate the effect of changing the parameters of the scanning strategy on the in-flight calibration effectiveness, the suppression of the systematic effects themselves, and the ability to distinguish systematic effects by null-tests. Next-generation missions such as LiteBIRD, modulated by a Half-Wave Plate (HWP), will be able to observe polarisation using a single detector, eliminating the need to combine several detectors to measure polarisation, as done in many previous experiments and hence avoiding the consequent systematic effects. While the HWP is expected to suppress many systematic effects, some of them will remain. We use an analytical approach to comprehensively address the mitigation of these systematic effects and identify the characteristics of scanning strategies that are the most effective for implementing a variety of calibration strategies in the multi-dimensional space of common spacecraft scan parameters. We verify that LiteBIRD's standard configuration yields good performance on the metrics we studied. We also present Falcons.jl, a fast spacecraft scanning simulator that we developed to investigate this scanning parameter space.

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Grumitt, R. D. P., Luke R. P. Jew, and C. Dickinson. "Hierarchical Bayesian CMB component separation with the No-U-Turn Sampler." Monthly Notices of the Royal Astronomical Society 496, no. 4 (2020): 4383–401. http://dx.doi.org/10.1093/mnras/staa1857.

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ABSTRACT In this paper, we present a novel implementation of Bayesian cosmic microwave background (CMB) component separation. We sample from the full posterior distribution using the No-U-Turn Sampler (NUTS), a gradient-based sampling algorithm. Alongside this, we introduce new foreground modelling approaches. We use the mean shift algorithm to define regions on the sky, clustering according to naively estimated foreground spectral parameters. Over these regions we adopt a complete pooling model, where we assume constant spectral parameters, and a hierarchical model, where we model individual pixel spectral parameters as being drawn from underlying hyperdistributions. We validate the algorithm against simulations of the LiteBIRD and C-Band All-Sky Survey (C-BASS) experiments, with an input tensor-to-scalar ratio of r = 5 × 10−3. Considering multipoles 30 ≤ ℓ &lt; 180, we are able to recover estimates for r. With LiteBIRD-only observations, and using the complete pooling model, we recover r = (12.9 ± 1.4) × 10−3. For C-BASS and LiteBIRD observations we find r = (9.0 ± 1.1) × 10−3 using the complete pooling model, and r = (5.2 ± 1.0) × 10−3 using the hierarchical model. Unlike the complete pooling model, the hierarchical model captures pixel-scale spatial variations in the foreground spectral parameters, and therefore produces cosmological parameter estimates with reduced bias, without inflating their uncertainties. Measured by the rate of effective sample generation, NUTS offers performance improvements of ∼103 over using Metropolis–Hastings to fit the complete pooling model. The efficiency of NUTS allows us to fit the more sophisticated hierarchical foreground model that would likely be intractable with non-gradient-based sampling algorithms.

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Krachmalnicoff, N., T. Matsumura, E. de la Hoz, et al. "In-flight polarization angle calibration for LiteBIRD: blind challenge and cosmological implications." Journal of Cosmology and Astroparticle Physics 2022, no. 01 (2022): 039. http://dx.doi.org/10.1088/1475-7516/2022/01/039.

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Abstract We present a demonstration of the in-flight polarization angle calibration for the JAXA/ISAS second strategic large class mission, LiteBIRD, and estimate its impact on the measurement of the tensor-to-scalar ratio parameter, r, using simulated data. We generate a set of simulated sky maps with CMB and polarized foreground emission, and inject instrumental noise and polarization angle offsets to the 22 (partially overlapping) LiteBIRD frequency channels. Our in-flight angle calibration relies on nulling the EB cross correlation of the polarized signal in each channel. This calibration step has been carried out by two independent groups with a blind analysis, allowing an accuracy of the order of a few arc-minutes to be reached on the estimate of the angle offsets. Both the corrected and uncorrected multi-frequency maps are propagated through the foreground cleaning step, with the goal of computing clean CMB maps. We employ two component separation algorithms, the Bayesian-Separation of Components and Residuals Estimate Tool (B-SeCRET), and the Needlet Internal Linear Combination (NILC). We find that the recovered CMB maps obtained with algorithms that do not make any assumptions about the foreground properties, such as NILC, are only mildly affected by the angle miscalibration. However, polarization angle offsets strongly bias results obtained with the parametric fitting method. Once the miscalibration angles are corrected by EB nulling prior to the component separation, both component separation algorithms result in an unbiased estimation of the r parameter. While this work is motivated by the conceptual design study for LiteBIRD, its framework can be broadly applied to any CMB polarization experiment. In particular, the combination of simulation plus blind analysis provides a robust forecast by taking into account not only detector sensitivity but also systematic effects.

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Sugai, H., P. A. R. Ade, Y. Akiba, et al. "Updated Design of the CMB Polarization Experiment Satellite LiteBIRD." Journal of Low Temperature Physics 199, no. 3-4 (2020): 1107–17. http://dx.doi.org/10.1007/s10909-019-02329-w.

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Jaehnig, G. C., K. Arnold, J. Austermann, et al. "Development of Space-Optimized TES Bolometer Arrays for LiteBIRD." Journal of Low Temperature Physics 199, no. 3-4 (2020): 646–53. http://dx.doi.org/10.1007/s10909-020-02425-2.

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Hattori, K., S. Ariyoshi, M. Hazumi, et al. "Novel Frequency-Domain Multiplexing MKID Readout for the LiteBIRD Satellite." Journal of Low Temperature Physics 167, no. 5-6 (2012): 671–77. http://dx.doi.org/10.1007/s10909-012-0506-x.

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Hasebe, Takashi, Yutaro Sekimoto, Tadayasu Dotani, Kazuhisa Mitsuda, Keisuke Shinozaki, and Seiji Yoshida. "Optimization of cryogenic architecture for LiteBIRD satellite using radiative cooling." Journal of Astronomical Telescopes, Instruments, and Systems 5, no. 04 (2019): 1. http://dx.doi.org/10.1117/1.jatis.5.4.044002.

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Shi, Rui, Tobias A. Marriage, John W. Appel, et al. "Testing Cosmic Microwave Background Anomalies in E-mode Polarization with Current and Future Data." Astrophysical Journal 945, no. 1 (2023): 79. http://dx.doi.org/10.3847/1538-4357/acb339.

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Abstract In this paper, we explore the power of the cosmic microwave background (CMB) polarization (E-mode) data to corroborate four potential anomalies in CMB temperature data: the lack of large angular-scale correlations, the alignment of the quadrupole and octupole (Q–O), the point-parity asymmetry, and the hemispherical power asymmetry. We use CMB simulations with noise representative of three experiments—the Planck satellite, the Cosmology Large Angular Scale Surveyor (CLASS), and the LiteBIRD satellite—to test how current and future data constrain the anomalies. We find the correlation coefficients ρ between temperature and E-mode estimators to be less than 0.1, except for the point-parity asymmetry (ρ = 0.17 for cosmic-variance-limited simulations), confirming that E-modes provide a check on the anomalies that is largely independent of temperature data. Compared to Planck component-separated CMB data (smica), the putative LiteBIRD survey would reduce errors on E-mode anomaly estimators by factors of ∼3 for hemispherical power asymmetry and point-parity asymmetry, and by ∼26 for lack of large-scale correlation. The improvement in Q–O alignment is not obvious due to large cosmic variance, but we found the ability to pin down the estimator value will be improved by a factor ≳100. Improvements with CLASS are intermediate to these.

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Researcher. "DETECTING THE IMPRINT OF PRIMORDIAL GRAVITATIONAL WAVES ON THE COSMIC MICROWAVE BACKGROUND POLARIZATION PATTERNS USING NEXT-GENERATION OBSERVATORIES." International Journal of Astronomy and Astrophysics (IJAA) 3, no. 1 (2025): 1–5. https://doi.org/10.5281/zenodo.14698472.

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The detection of primordial gravitational waves (PGWs) is a pivotal goal in modern cosmology, providing direct evidence for inflationary theory. Their faint imprints on the polarization patterns of the Cosmic Microwave Background (CMB) radiation, specifically in the B-mode polarization, hold the key. Next-generation observatories such as CMB-S4 and LiteBIRD promise unprecedented sensitivity to these signals. This paper discusses theoretical and observational progress, reviews recent advancements, and explores methodologies for analyzing PGW imprints on CMB polarization patterns.

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Hasebe, T., S. Kashima, P. A. R. Ade, et al. "Concept Study of Optical Configurations for High-Frequency Telescope for LiteBIRD." Journal of Low Temperature Physics 193, no. 5-6 (2018): 841–50. http://dx.doi.org/10.1007/s10909-018-1915-2.

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Duval, Jean-Marc, Thomas Prouvé, Peter Shirron, et al. "LiteBIRD Cryogenic Chain: 100 mK Cooling with Mechanical Coolers and ADRs." Journal of Low Temperature Physics 199, no. 3-4 (2020): 730–36. http://dx.doi.org/10.1007/s10909-020-02371-z.

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Hattori, K., M. Hazumi, H. Ishino, et al. "Development of microwave kinetic inductance detectors and their readout system for LiteBIRD." Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 732 (December 2013): 306–10. http://dx.doi.org/10.1016/j.nima.2013.08.019.

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Carones, Alessandro, Marina Migliaccio, Giuseppe Puglisi, et al. "Multiclustering needlet ILC for CMB B-mode component separation." Monthly Notices of the Royal Astronomical Society 525, no. 2 (2023): 3117–35. http://dx.doi.org/10.1093/mnras/stad2423.

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ABSTRACT The Cosmic Microwave Background (CMB) primordial B-mode signal is predicted to be much lower than the polarized Galactic emission (foregrounds) in any region of the sky pointing to the need for sophisticated component separation methods. Among them, the blind Needlet Internal Linear Combination (NILC) has great relevance given our current poor knowledge of the B-mode foregrounds. However, the expected level of spatial variability of the foreground spectral properties complicates the NILC subtraction of the Galactic contamination. We therefore propose a novel extension of the NILC approach, the Multiclustering NILC (MC-NILC), which performs NILC variance minimization on separate regions of the sky (clusters) properly chosen to have similar spectral properties of the B-mode Galactic emission within them. Clusters are identified thresholding either the ratio of simulated foregrounds-only B modes (ideal case) or the one of cleaned templates of Galactic emission obtained from realistic simulations. In this work we present an application of MC-NILC to the future LiteBIRD satellite, which targets the observation of both reionization and recombination peaks of the primordial B-mode angular power spectrum with a total error on the tensor-to-scalar ratio δr &lt; 0.001. We show that MC-NILC provides a CMB solution with residual foreground and noise contamination that is significantly lower than the NILC one and the primordial signal targeted by LiteBIRD at all angular scales for the ideal case and at the reionization peak for a realistic ratio. Thus, MC-NILC will represent a powerful method to mitigate B-mode foregrounds for future CMB polarization experiments.

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Vielva, P., E. Martínez-González, F. J. Casas, et al. "Polarization angle requirements for CMB B-mode experiments. Application to the LiteBIRD satellite." Journal of Cosmology and Astroparticle Physics 2022, no. 04 (2022): 029. http://dx.doi.org/10.1088/1475-7516/2022/04/029.

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Abstract A methodology to provide the polarization angle requirements for different sets of detectors, at a given frequency of a CMB polarization experiment, is presented. The uncertainties in the polarization angle of each detector set are related to a given bias on the tensor-to-scalar ratio r parameter. The approach is grounded in using a linear combination of the detector sets to obtain the CMB polarization signal. In addition, assuming that the uncertainties on the polarization angle are in the small angle limit (lower than a few degrees), it is possible to derive analytic expressions to establish the requirements. The methodology also accounts for possible correlations among detectors, that may originate from the optics, wafers, etc. The approach is applied to the LiteBIRD space mission. We show that, for the most restrictive case (i.e., full correlation of the polarization angle systematics among detector sets), the requirements on the polarization angle uncertainties are of around 1 arcmin at the most sensitive frequency bands (i.e., ≈ 150 GHz) and of few tens of arcmin at the lowest (i.e., ≈ 40 GHz) and highest (i.e., ≈ 400 GHz) observational bands. Conversely, for the least restrictive case (i.e., no correlation of the polarization angle systematics among detector sets), the requirements are ≈ 5 times less restrictive than for the previous scenario. At the global and the telescope levels, polarization angle knowledge of a few arcmins is sufficient for correlated global systematic errors and can be relaxed by a factor of two for fully uncorrelated errors in detector polarization angle. The reported uncertainty levels are needed in order to have the bias on r due to systematics below the limit established by the LiteBIRD collaboration.

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Petretti, Catherine, Matteo Braglia, Xingang Chen, Dhiraj Kumar Hazra, and Sonia Paban. "Investigating the origin of CMB large-scale features using LiteBIRD and CMB-S4." Journal of Cosmology and Astroparticle Physics 2025, no. 06 (2025): 035. https://doi.org/10.1088/1475-7516/2025/06/035.

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Abstract Several missions following Planck are currently under development, which will provide high-precision measurements of the Cosmic Microwave Background (CMB) anisotropies. Specifically, measurements of the E modes will become nearly limited by cosmic variance, which, especially when considering the sharpness of the E-mode transfer functions, may allow for the ability to detect deviations from the concordance model in the CMB data. We investigate the capability of upcoming missions to scrutinize models that have been proposed to address large-scale anomalies observed in the temperature spectra from WMAP and Planck. To this purpose, we consider four benchmarks that modify the CMB angular power spectra at large scales: models producing suppression, a dip, and amplification in the primordial scalar power spectrum, as well as a beyond-ΛCDM prescription of dark energy. Our analysis shows that large-scale measurements from LiteBIRD will be able to distinguish between various types of primordial and late-time models that predict modifications to the angular spectra at these scales. Moreover, if these deviations from the standard cosmological model are determined to be systematic and do not reflect the true universe model, future experiments could potentially dismiss these features as statistical fluctuations. We also show that additional measurements from CMB-S4 can impose more stringent constraints by probing correlated signals that these models predict at smaller scales (ℓ≳ 100). A byproduct of our analysis is that a recently proposed “Dark Dimension” scenario, featuring power amplification at large scales, is strongly bound by current data, pushing the deviation from the standard model to unobservable scales. Overall, our results demonstrate that future CMB measurements can provide valuable insights into large-scale anomalies that are present in the current CMB data.

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Dimastrogiovanni, Emanuela, Matteo Fasiello, and A. Emir Gümrükçüoğlu. "Spinning guest fields during inflation: leftover signatures." Journal of Cosmology and Astroparticle Physics 2021, no. 11 (2021): 047. http://dx.doi.org/10.1088/1475-7516/2021/11/047.

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Abstract We consider the possibility of extra spinning particles during inflation, focussing on the spin-2 case. Our analysis relies on the well-known fully non-linear formulation of interacting spin-2 theories. We explore the parameter space of the corresponding inflationary Lagrangian and identify regions therein exhibiting signatures within reach of upcoming CMB probes. We provide a thorough study of the early and late-time dynamics ensuring that stability conditions are met throughout the cosmic evolution. We characterise in particular the gravitational wave spectrum and three-point function finding a local-type non-Gaussianity whose amplitude may be within the sensitivity range of both the LiteBIRD and CMB-S4 experiments.

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Kallosh, Renata, та Andrei Linde. "SL(2,ℤ) cosmological attractors". Journal of Cosmology and Astroparticle Physics 2025, № 04 (2025): 045. https://doi.org/10.1088/1475-7516/2025/04/045.

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Abstract We study cosmological theory where the kinetic term and potential have SL(2,ℤ) symmetry. Potentials have a plateau at large values of the inflaton field, where the axion forms a flat direction. Due to the underlying hyperbolic geometry and special features of SL(2,ℤ) potentials, the theory exhibits an α-attractor behavior: its cosmological predictions are stable with respect to significant modifications of the SL(2,ℤ) invariant potentials. We present a supersymmetric version of this theory in the framework of D3 induced geometric inflation. The choice of α is determined by underlying string compactification. For example, in a CY compactification with T 2, one has 3α = 1, the lowest discrete Poincaré disk target for LiteBIRD.

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Takakura, Hayato, Yutaro Sekimoto, Junji Inatani, et al. "Far-Sidelobe Antenna Pattern Measurement of LiteBIRD Low Frequency Telescope in 1/4 Scale." IEEE Transactions on Terahertz Science and Technology 9, no. 6 (2019): 598–605. http://dx.doi.org/10.1109/tthz.2019.2937497.

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Leloup, C., G. Patanchon, J. Errard, et al. "Impact of beam far side-lobe knowledge in the presence of foregrounds for LiteBIRD." Journal of Cosmology and Astroparticle Physics 2024, no. 06 (2024): 011. http://dx.doi.org/10.1088/1475-7516/2024/06/011.

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Abstract 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 foregrounds between the dipole and higher multipoles which degrads the performances of component separation methods. This leads to foreground residuals in the CMB map. It is expected to be one of the main source of systematic effects in future CMB polarization observations. Thus, it becomes crucial for all-sky survey missions to take into account the interplays between beam systematic effects and all the data analysis steps. LiteBIRD is the ISAS/JAXA second strategic large-class satellite mission and is dedicated to target the measurement of CMB primordial B modes by reaching a sensitivity on the tensor-to-scalar ratio r of σ(r) ≤ 10-3 assuming r = 0. The primary goal of this paper is to provide the methodology and develop the framework to carry out the end-to-end study of beam far side-lobe effects for a space-borne CMB experiment. We introduce uncertainties in the beam model, and propagate the beam effects through all the steps of the analysis pipeline, most importantly including component separation, up to the cosmological results in the form of a bias δr. As a demonstration of our framework, we derive requirements on the calibration and modeling for the LiteBIRD's beams under given assumptions on design, simulation, component separation method and allocated error budget. In particular, we assume a parametric method of component separation with no mitigation of the far side-lobes effect at any stage of the analysis pipeline. We show that δr is mostly due to the integrated fractional power difference between the estimated beams and the true beams in the far side-lobes region, with little dependence on the actual shape of the beams, for low enough δr. Under our set of assumptions, in particular considering the specific foreground cleaning method we used, we find that the integrated fractional power in the far side-lobes should be known at the level of ∼ 10-4, to achieve the required limit on the bias δr < 1.9 × 10-5. The framework and tools developed for this study can be easily adapted to provide requirements under different design, data analysis frameworks and for other future space-borne experiments, such as PICO or CMB-Bharat. We further discuss the limitations of this framework and potential extensions to circumvent them.

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Ritacco, A., R. Adam, P. Ade, et al. "Crab nebula at 260 GHz with the NIKA2 polarimeter: Implications for the polarization angle calibration of future CMB experiments." EPJ Web of Conferences 257 (2022): 00042. http://dx.doi.org/10.1051/epjconf/202225700042.

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The quest for primordial gravitational waves enclosed in the Cosmic Microwave Background (CMB) polarization B-modes signal motivates the development of a new generation of high sensitive experiments (e.g. CMBS4, LiteBIRD), thus allowing to probe the inflationary epoch in the early Universe. However, this will be only possible by ensuring a high control of the instrumental systematic effects and an accurate absolute calibration of the polarization angle. The Crab nebula is known to be a polarization calibrator on the sky for CMB experiments. Already used for the Planck satellite it exhibits a high polarized signal at microwave wavelengths. In this work we present Crab polarization observations obtained, in the 260 GHz frequency band, with the NIKA2 instrument. Furthermore, we discuss the accuracy needed on such a measurement to improve the constraints on the absolute angle calibration for CMB experiments.

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36

Väliviita, Jussi. "Power spectra based Planck constraints on compensated isocurvature, and forecasts for LiteBIRD and CORE space missions." Journal of Cosmology and Astroparticle Physics 2017, no. 04 (2017): 014. http://dx.doi.org/10.1088/1475-7516/2017/04/014.

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Hamann, Jan, and Ameek Malhotra. "Constraining primordial tensor features with the anisotropies of the cosmic microwave background." Journal of Cosmology and Astroparticle Physics 2022, no. 12 (2022): 015. http://dx.doi.org/10.1088/1475-7516/2022/12/015.

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Abstract It is commonly assumed that the stochastic background of gravitational waves on cosmological scales follows an almost scale-independent power spectrum, as generically predicted by the inflationary paradigm. However, it is not inconceivable that the spectrum could have strongly scale-dependent features, generated, e.g., via transient dynamics of spectator axion-gauge fields during inflation. Using the temperature and polarisation maps from the Planck and BICEP/Keck datasets, we search for such features, taking the example of a log-normal bump in the primordial tensor spectrum at CMB scales. We do not find any evidence for the existence of bump-like tensor features at present, but demonstrate that future CMB experiments such as LiteBIRD and CMB-S4 will greatly improve our prospects of determining the amplitude, location and width of such a bump. We also highlight the role of delensing in constraining these features at angular scales ℓ ≳ 100.

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Hazumi, M., P. A. R. Ade, Y. Akiba, et al. "LiteBIRD: A Satellite for the Studies of B-Mode Polarization and Inflation from Cosmic Background Radiation Detection." Journal of Low Temperature Physics 194, no. 5-6 (2019): 443–52. http://dx.doi.org/10.1007/s10909-019-02150-5.

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Moursy, Ahmad, and Qaisar Shafi. "Primordial monopoles, black holes and gravitational waves." Journal of Cosmology and Astroparticle Physics 2024, no. 08 (2024): 064. http://dx.doi.org/10.1088/1475-7516/2024/08/064.

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Abstract We show how topologically stable superheavy magnetic monopoles and primordial black holes can be generated at observable levels by the waterfall field in hybrid inflation models based on grand unified theories. In SU(5) ×U(1) χ grand unification, the monopole mass is of order 4 × 1017 GeV, and it carries a single unit (2 π /e) of Dirac magnetic charge as well as screened color magnetic charge. The monopole density is partially diluted to an observable value, and accompanied with the production of primordial black holes with mass of order 1017–1019 g which may make up the entire dark matter in the universe. The tensor to scalar ratio r is predicted to be of order 10-5–10 -4 which should be testable in the next generation of CMB experiments such as CMB-S4 and LiteBIRD. The gravitational wave spectrum generated during the waterfall transition is also presented. The observed baryon asymmetry can be explained via leptogenesis.

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Raffuzzi, N., M. Lembo, S. Giardiello, et al. "Unveiling V modes: enhancing CMB sensitivity to BSM physics with a non-ideal half-wave plate." Journal of Cosmology and Astroparticle Physics 2025, no. 03 (2025): 009. https://doi.org/10.1088/1475-7516/2025/03/009.

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Abstract V-mode polarization of the cosmic microwave background is expected to be vanishingly small in the ΛCDM model and, hence, usually ignored. Nonetheless, several astrophysical effects, as well as beyond standard model physics could produce it at a detectable level. A realistic half-wave plate — an optical element commonly used in CMB experiments to modulate the polarized signal — can provide sensitivity to V modes without significantly spoiling that to linear polarization. We assess this sensitivity for some new-generation CMB experiments, such as the LiteBIRD satellite, the ground-based Simons Observatory and a CMB-S4-like experiment. We forecast the efficiency of these experiments to constrain the phenomenology of certain classes of BSM models inducing mixing of linear polarization states and generation of V modes in the CMB. We find that new-generation experiments can improve current limits by 1-to-3 orders of magnitude, depending on the data combination. The inclusion of V-mode information dramatically boosts the sensitivity to these BSM models.

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Hirota, Y., H. Ohsaki, Y. Terao, et al. "Evaluation of loss characteristics of superconducting magnetic bearings for LiteBIRD satellite by three-dimensional finite element method analysis." Journal of Physics: Conference Series 1293 (September 2019): 012086. http://dx.doi.org/10.1088/1742-6596/1293/1/012086.

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Akama, Shingo, Giorgio Orlando, and Paola C. M. Delgado. "Towards testing the general bounce cosmology with the CMB B-mode auto-bispectrum." Journal of Cosmology and Astroparticle Physics 2024, no. 09 (2024): 055. http://dx.doi.org/10.1088/1475-7516/2024/09/055.

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Abstract It has been shown that a three-point correlation function of tensor perturbations from a bounce model in general relativity with a minimally-coupled scalar field is highly suppressed, and the resultant three-point function of cosmic microwave background (CMB) B-mode polarizations is too small to be detected by CMB experiments. On the other hand, bounce models in a more general class with a non-minimal derivative coupling between a scalar field and gravity can predict the three-point correlation function of the tensor perturbations without any suppression, the amplitude of which is allowed to be much larger than that in general relativity. In this paper, we evaluate the three-point function of the B-mode polarizations from the general bounce cosmology with the non-minimal coupling and show that a signal-to-noise ratio of the B-mode auto-bispectrum in the general class can reach unity for ℓ max=100 in the full-sky case, with and without the lensing B-mode added to cosmic variance. Considering additionally the LiteBIRD experimental noise, we obtain a SNR smaller than unity.

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Kubota, Kei-ichiro, Hiroki Matsui та Takahiro Terada. "Inflationary α-attractor models with singular derivative of potential". Journal of Cosmology and Astroparticle Physics 2023, № 07 (2023): 011. http://dx.doi.org/10.1088/1475-7516/2023/07/011.

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Abstract A generalization of inflationary α-attractor models (polynomial α-attractor) was recently proposed by Kallosh and Linde, in which the potential involves logarithmic functions of the inflaton so that the derivative of the potential but not potential itself has a singularity. We find that the models can lead to viable inflationary observables even without the pole in the kinetic term. Also, the generalization with a pole order other than two does not significantly change the functional form of the potential. This allows a systematic analysis of the predictions of this class of models. Our models predict larger spectral index ns and tensor-to-scalar ratio r than in the polynomial α-attractor: typically, ns around 0.97–0.98 and r observable by LiteBIRD. Taking advantage of the relatively large ns , we discuss the modification of the potential to produce primordial black holes as the whole dark matter and gravitational waves induced by curvature perturbations detectable by LISA and BBO/DECIGO, while keeping ns in agreement with the Planck/BICEP/Keck data.

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Aoki, Mayumi, Jisuke Kubo, and Jinbo Yang. "Scale invariant extension of the Standard Model: a nightmare scenario in cosmology." Journal of Cosmology and Astroparticle Physics 2024, no. 05 (2024): 096. http://dx.doi.org/10.1088/1475-7516/2024/05/096.

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Abstract Inflationary observables of a classically scale invariant model, in which the origin of the Planck mass and the electroweak scale including the right-handed neutrino mass is chiral symmetry breaking in a QCD-like hidden sector, are studied. Despite a three-field inflation the initial-value-dependence is strongly suppressed thanks to a river-valley like potential. The model predicts the tensor-to-scalar ratio r of cosmological perturbations smaller than that of the R 2 inflation, i.e., 0.0044 ≳ r ≳ 0.0017 for e-foldings between 50 and 60: the model will be consistent even with a null detection at LiteBird/CMB-S4. We find that the non-Gaussianity parameter f NL is O(10-2), the same size as that of single-field inflation. The dark matter particles are the lightest Nambu-Goldstone bosons associated with chiral symmetry breaking, which are decay products of one of the inflatons and are heavier than 109 GeV with a strongly suppressed coupling with the standard model, implying that the dark matter will be unobservable in direct as well as indirect measurements.

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Zhou, Yuyang, Adrian Lee, and Yuji Chinone. "Map-based E/B separation of filtered timestreams using space-based E-mode observations." Journal of Cosmology and Astroparticle Physics 2025, no. 03 (2025): 048. https://doi.org/10.1088/1475-7516/2025/03/048.

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Abstract E to B mixing or "leakage" due to time-ordered data (TOD) filtering has become an important source of sensitivity loss that ground-based cosmic microwave background polarization experiments must address. However, it is a difficult problem for which very few viable solutions exist. In this paper, we expand upon satellite E-mode methods to cover E/B leakage specifically due to TOD filtering. We take a satellite E-mode map and TOD filter it through the ground-based experiment data analysis pipeline, from which we construct a map-space "leakage template" and subtract it from the ground-based experiment map. We evaluate the residual leakage by simulating the satellite E-mode maps with Planck-like and LiteBIRD-like noise levels, and simulate the ground-based experiment with Simons Observatory-like and CMB-S4-like noise levels. The effectiveness of the method is measured in the improvement of the Fisher uncertainty σ(r = 0). We find that our method can reduce σ(r = 0) by ∼ 15–75% depending on the noise levels considered.

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46

Namikawa, Toshiya. "CMB mode coupling with isotropic polarization rotation." Monthly Notices of the Royal Astronomical Society 506, no. 1 (2021): 1250–57. http://dx.doi.org/10.1093/mnras/stab1796.

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ABSTRACT We provide a new analysis technique to measure the effect of the isotropic polarization rotation, induced by e.g. the isotropic cosmic birefringence from axion-like particles and a miscalibration of cosmic microwave background (CMB) polarization angle, via mode coupling in the CMB. Several secondary effects such as gravitational lensing and CMB optical-depth anisotropies lead to mode coupling in observed CMB anisotropies, i.e. non-zero off-diagonal elements in the observed CMB covariance. To derive the mode coupling, however, we usually assume no parity violation in the observed CMB anisotropies. We first derive a new contribution to the CMB mode coupling arising from parity violation in observed CMB. Since the isotropic polarization rotation leads to parity violation in the observed CMB anisotropies, we then discuss the use of the new mode coupling for constraining the isotropic polarization angle. We find that constraints on the isotropic polarization angle by measuring the new mode-coupling contribution are comparable to that using the EB cross-power spectrum in future high-sensitivity polarization experiments such as CMB-S4 and LiteBIRD. Thus, this technique can be used to cross-check results obtained by the use of the EB cross-power spectrum.

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Revin, Leonid S., Dmitry A. Pimanov, Alexander V. Chiginev, et al. "Measurements of dichroic bow-tie antenna arrays with integrated cold-electron bolometers using YBCO oscillators." Beilstein Journal of Nanotechnology 15 (January 4, 2024): 26–36. http://dx.doi.org/10.3762/bjnano.15.3.

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We consider properties of dichroic antenna arrays on a silicon substrate with integrated cold-electron bolometers to detect radiation at frequencies of 210 and 240 GHz. This frequency range is widely used in cosmic microwave background experiments in space, balloon, and ground-based missions such as BICEP Array, LSPE, LiteBIRD, QUBIC, Simons Observatory, and AliCPT. As a direct radiation detector, we use cold-electron bolometers, which have high sensitivity and a wide operating frequency range, as well as immunity to spurious cosmic rays. Their other advantages are the compact size of the order of a few micrometers and the effect of direct electron cooling, which can improve sensitivity in typical closed-loop cycle 3He cryostats for space applications. We study a novel concept of cold-electron bolometers with two SIN tunnel junctions and one SN contact. The amplitude–frequency characteristics measured with YBCO Josephson Junction oscillators show narrow peaks at 205 GHz for the 210 GHz array and at 225 GHz for the 240 GHz array; the separation of these two frequency bands is clearly visible. The noise equivalent power level at an operating point in the current bias mode is 5 × 10−16 W/√Hz.

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Bayer, Adrian E., Yici Zhong, Zack Li, Joseph DeRose, Yu Feng, and Jia Liu. "The HalfDome multi-survey cosmological simulations: N-body simulations." Journal of Cosmology and Astroparticle Physics 2025, no. 05 (2025): 016. https://doi.org/10.1088/1475-7516/2025/05/016.

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Abstract Upcoming cosmological surveys have the potential to reach groundbreaking discoveries on multiple fronts, including the neutrino mass, dark energy, and inflation. Most of the key science goals require the joint analysis of datasets from multiple surveys to break parameter degeneracies and calibrate systematics. To realize such analyses, a large set of mock simulations that realistically model correlated observables is required. In this paper we present the N-body component of the HalfDome cosmological simulations, designed for the joint analysis of Stage-IV cosmological surveys, such as Rubin LSST, Euclid, SPHEREx, Roman, DESI, PFS, Simons Observatory, CMB-S4, and LiteBIRD. Our 300TB initial data release includes full-sky lightcones and halo catalogs between z = 0–4 for 11 fixed cosmology realizations, as well as an additional run with local primordial non-Gaussianity (f NL = 20). The simulations evolve 61443 particles in a 3.75 h -1 Gpc box, reaching a minimum halo mass of ∼6 × 1012 h -1 M ⊙ and maximum scale of k ∼ h Mpc-1. Our data is publicly available: instructions to access the data and plans for future data releases can be found at https://halfdomesims.github.io.

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Lagache, G., M. Béthermin, L. Montier, P. Serra, and M. Tucci. "Impact of polarised extragalactic sources on the measurement of CMB B-mode anisotropies." Astronomy & Astrophysics 642 (October 2020): A232. http://dx.doi.org/10.1051/0004-6361/201937147.

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One of the main goals of cosmology is to search for the imprint of primordial gravitational waves in the polarisation filed of the cosmic microwave background to probe inflation theories. One of the obstacles in detecting the primordial signal is that the cosmic microwave background B-mode polarisation must be extracted from among astrophysical contaminations. Most efforts have focus on limiting Galactic foreground residuals, but extragalactic foregrounds cannot be ignored at the large scale (ℓ ≲ 150), where the primordial B-modes are the brightest. We present a complete analysis of extragalactic foreground contamination that is due to polarised emission of radio and dusty star-forming galaxies. We update or use current models that are validated using the most recent measurements of source number counts, shot noise, and cosmic infrared background power spectra. We predict the flux limit (confusion noise) for future cosmic microwave background (CMB) space-based or balloon-borne experiments (IDS, PIPER, SPIDER, LiteBIRD, and PICO), as well as ground-based experiments (C-BASS, NEXT-BASS, QUIJOTE, AdvACTPOL, BICEP3+Keck, BICEPArray, CLASS, Simons Observatory, SPT3G, and S4). The telescope aperture size (and frequency) is the main characteristic that affects the level of confusion noise. Using the flux limits and assuming mean polarisation fractions independent of flux and frequency for radio and dusty galaxies, we computed the B-mode power spectra of the three extragalactic foregrounds (radio source shot noise, dusty galaxy shot noise, and clustering). We discuss their relative levels and compare their amplitudes to that of the primordial tensor modes parametrised by the tensor-to-scalar ratio r. At the reionisation bump (ℓ = 5), contamination by extragalactic foregrounds is negligible. While the contamination is much lower than the targeted sensitivity on r for large-aperture telescopes at the recombination peak (ℓ = 80), it is at a comparable level for some of the medium- (∼1.5 m) and small-aperture telescope (≤0.6 m) experiments. For example, the contamination is at the level of the 68% confidence level uncertainty on the primordial r for the LiteBIRD and PICO space-based experiments. These results were obtained in the absence of multi-frequency component separation (i.e. considering each frequency independently). We stress that extragalactic foreground contaminations have to be included in the input sky models of component separation methods dedicated to the recovery of the CMB primordial B-mode power spectrum. Finally, we also provide some useful unit conversion factors and give some predictions for the SPICA B-BOP experiment, which is dedicated to Galactic and extragalactic polarisation studies. We show that SPICA B-BOP will be limited at 200 and 350 μm by confusion from extragalactic sources for long integrations in polarisation, but very short integrations in intensity.

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NI, WEI-TOU. "COSMIC POLARIZATION ROTATION, COSMOLOGICAL MODELS, AND THE DETECTABILITY OF PRIMORDIAL GRAVITATIONAL WAVES." International Journal of Modern Physics A 24, no. 18n19 (2009): 3493–500. http://dx.doi.org/10.1142/s0217751x09047107.

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CMB (Cosmic Microwave Background) polarization observations test many aspects of cosmological models. Effective pseudoscalar-photon interaction(s) would induce a rotation of linear polarization of electromagnetic wave propagating with cosmological distance in various cosmological models. CMB polarization observations are superb tests of these models and have the potential to discover new fundamental physics. Pseudoscalar-photon interaction is proportional to the gradient of the pseudoscalar field. From phenomenological point of view, this gradient could be neutrino number asymmetry, other density current, or a constant vector. In these situations, Lorentz invariance or CPT may effectively be violated. In this paper, we review these results and anticipate what more precise observations can tell us about fundamental physics, inflation, etc. Better accuracy in CMB polarization observation is expected from PLANCK mission to be launched this year. Dedicated CMB polarization observers like B-Pol mission, CMBpol mission and LiteBIRD mission would probe this fundamental issue more deeply in the future. With these sensitivities, cosmic polarization rotations from effective pseudoscalar-photon interaction, Faraday polarization rotations from primordial and large-scale magnetic field, and tensor modes effects would have chances to be detected and distinguished. The subtracted tensor-mode effects are likely due to primordial gravitational waves. We discuss the direct detectability of these primordial gravitational waves using space GW detectors.

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Journal articles on the topic 'LiteBIRD'

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