Journal articles: 'LiteBIRD'

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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, D. Molinari, J. Chluba, F. Finelli, C. Baccigalupi, et al. "LiteBIRD science goals and forecasts: primordial magnetic fields." Journal of Cosmology and Astroparticle Physics 2024, no. 07 (July 1, 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, N. Bartolo, D. Beck, K. Benabed, A. Challinor, 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 (June 1, 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, Y. Chinone, M. Dobbs, H. Fuke, A. Ghribi, et al. "Mission Design of LiteBIRD." Journal of Low Temperature Physics 176, no. 5-6 (January 23, 2014): 733–40. http://dx.doi.org/10.1007/s10909-013-0996-1.

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Campeti, P., E. Komatsu, C. Baccigalupi, M. Ballardini, N. Bartolo, A. Carones, J. Errard, 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 (June 1, 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 (March 1, 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, P. Diego-Palazuelos, M. Ruiz-Granda, M. Migliaccio, C. Baccigalupi, 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 (June 1, 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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Remazeilles, Mathieu, Andrea Ravenni, and 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, no. 1 (February 24, 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, J. Borrill, R. Chendra, Y. Chinone, A. Cukierman, et al. "LiteBIRD: Mission Overview and Focal Plane Layout." Journal of Low Temperature Physics 184, no. 3-4 (April 6, 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, D. Alonso, K. Arnold, J. Aumont, C. Baccigalupi, et al. "The LiteBIRD Satellite Mission: Sub-Kelvin Instrument." Journal of Low Temperature Physics 193, no. 5-6 (May 10, 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 (May 1, 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, J. Errard, A. Gruppuso, H. Ishino, M. Lattanzi, 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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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 (June 26, 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 < 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, S. Basak, A. Gruppuso, Y. Minami, C. Baccigalupi, et al. "In-flight polarization angle calibration for LiteBIRD: blind challenge and cosmological implications." Journal of Cosmology and Astroparticle Physics 2022, no. 01 (January 1, 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, D. Alonso, K. Arnold, J. Aumont, J. Austermann, et al. "Updated Design of the CMB Polarization Experiment Satellite LiteBIRD." Journal of Low Temperature Physics 199, no. 3-4 (January 27, 2020): 1107–17. http://dx.doi.org/10.1007/s10909-019-02329-w.

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Jaehnig, G. C., K. Arnold, J. Austermann, D. Becker, S. Duff, N. W. Halverson, M. Hazumi, et al. "Development of Space-Optimized TES Bolometer Arrays for LiteBIRD." Journal of Low Temperature Physics 199, no. 3-4 (March 25, 2020): 646–53. http://dx.doi.org/10.1007/s10909-020-02425-2.

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Hattori, K., S. Ariyoshi, M. Hazumi, H. Ishino, A. Kibayashi, S. Mima, C. Otani, et al. "Novel Frequency-Domain Multiplexing MKID Readout for the LiteBIRD Satellite." Journal of Low Temperature Physics 167, no. 5-6 (January 20, 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 (October 9, 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, Charles L. Bennett, David T. Chuss, Joseph Cleary, Joseph R. Eimer, et al. "Testing Cosmic Microwave Background Anomalies in E-mode Polarization with Current and Future Data." Astrophysical Journal 945, no. 1 (March 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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Hasebe, T., S. Kashima, P. A. R. Ade, Y. Akiba, D. Alonso, K. Arnold, J. Aumont, et al. "Concept Study of Optical Configurations for High-Frequency Telescope for LiteBIRD." Journal of Low Temperature Physics 193, no. 5-6 (May 11, 2018): 841–50. http://dx.doi.org/10.1007/s10909-018-1915-2.

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Duval, Jean-Marc, Thomas Prouvé, Peter Shirron, Keisuke Shinozaki, Yutaro Sekimoto, Takashi Hasebe, Gerard Vermeulen, et al. "LiteBIRD Cryogenic Chain: 100 mK Cooling with Mechanical Coolers and ADRs." Journal of Low Temperature Physics 199, no. 3-4 (February 13, 2020): 730–36. http://dx.doi.org/10.1007/s10909-020-02371-z.

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Hattori, K., M. Hazumi, H. Ishino, A. Kibayashi, Y. Kibe, S. Mima, T. Okamura, 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, Carlo Baccigalupi, Domenico Marinucci, Nicola Vittorio, and Davide Poletti. "Multiclustering needlet ILC for CMB B-mode component separation." Monthly Notices of the Royal Astronomical Society 525, no. 2 (August 21, 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 < 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, T. Matsumura, S. Henrot-Versillé, E. Komatsu, J. Aumont, et al. "Polarization angle requirements for CMB B-mode experiments. Application to the LiteBIRD satellite." Journal of Cosmology and Astroparticle Physics 2022, no. 04 (April 1, 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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Dimastrogiovanni, Emanuela, Matteo Fasiello, and A. Emir Gümrükçüoğlu. "Spinning guest fields during inflation: leftover signatures." Journal of Cosmology and Astroparticle Physics 2021, no. 11 (November 1, 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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Takakura, Hayato, Yutaro Sekimoto, Junji Inatani, Shingo Kashima, Hiroaki Imada, Takashi Hasebe, Toru Kaga, Yoichi Takeda, and Norio Okada. "Far-Sidelobe Antenna Pattern Measurement of LiteBIRD Low Frequency Telescope in 1/4 Scale." IEEE Transactions on Terahertz Science and Technology 9, no. 6 (November 2019): 598–605. http://dx.doi.org/10.1109/tthz.2019.2937497.

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Leloup, C., G. Patanchon, J. Errard, C. Franceschet, J. E. Gudmundsson, S. Henrot-Versillé, H. Imada, 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 (June 1, 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, H. Ajeddig, P. André, E. Artis, J. Aumont, 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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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 (April 10, 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 (December 1, 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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Moursy, Ahmad, and Qaisar Shafi. "Primordial monopoles, black holes and gravitational waves." Journal of Cosmology and Astroparticle Physics 2024, no. 08 (August 1, 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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Hazumi, M., P. A. R. Ade, Y. Akiba, D. Alonso, K. Arnold, J. Aumont, C. Baccigalupi, 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 (February 26, 2019): 443–52. http://dx.doi.org/10.1007/s10909-019-02150-5.

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Hirota, Y., H. Ohsaki, Y. Terao, H. Enokida, Y. Sakurai, T. Matsumura, H. Sugai, and N. Katayama. "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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Kubota, Kei-ichiro, Hiroki Matsui, and Takahiro Terada. "Inflationary α-attractor models with singular derivative of potential." Journal of Cosmology and Astroparticle Physics 2023, no. 07 (July 1, 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 (May 1, 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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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 (September 1, 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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Namikawa, Toshiya. "CMB mode coupling with isotropic polarization rotation." Monthly Notices of the Royal Astronomical Society 506, no. 1 (June 25, 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, Anton V. Blagodatkin, Viktor O. Zbrozhek, Andrey V. Samartsev, Anastasia N. Orlova, 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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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 (July 30, 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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Paoletti, D., and F. Finelli. "Constraints on primordial magnetic fields from magnetically-induced perturbations: current status and future perspectives with LiteBIRD and future ground based experiments." Journal of Cosmology and Astroparticle Physics 2019, no. 11 (November 22, 2019): 028. http://dx.doi.org/10.1088/1475-7516/2019/11/028.

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Sherwin, Blake D., and Toshiya Namikawa. "Cosmic birefringence tomography and calibration independence with reionization signals in the CMB." Monthly Notices of the Royal Astronomical Society 520, no. 3 (February 14, 2023): 3298–304. http://dx.doi.org/10.1093/mnras/stac3146.

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ABSTRACT The search for cosmic polarization rotation or birefringence in the cosmic microwave background (CMB) is well motivated because it can provide powerful constraints on parity-violating new physics, such as axion-like particles. In this paper, we point out that since the CMB polarization is produced at two very different redshifts – it is generated at both reionization and recombination – new parity-violating physics can generically rotate the polarization signals from these different sources by different amounts. We explore two implications of this. First, measurements of CMB birefringence are challenging because the effect is degenerate with a miscalibration of CMB polarization angles; however, by taking the difference of the reionization and recombination birefringence angles (measured from different CMB angular scales), we can obtain a cosmological signal that is immune to instrumental angle miscalibration. Secondly, we note that the combination with other methods for probing birefringence can give tomographic information, constraining the redshift origin of any physics producing birefringence. We forecast that the difference of the reionization and recombination birefringence angles can be competitively determined to within ∼0.05 deg for future CMB satellites such as LiteBIRD. Although much further work is needed, we argue that foreground mitigation for this measurement should be less challenging than for inflationary B-mode searches on similar scales due to larger signals and lower foregrounds.

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Stever, S. L., T. Ghigna, M. Tominaga, G. Puglisi, M. Tsujimoto, M. Zeccoli Marazzini, M. Baratto, et al. "Simulations of systematic effects arising from cosmic rays in the LiteBIRD space telescope, and effects on the measurements of CMB B-modes." Journal of Cosmology and Astroparticle Physics 2021, no. 09 (September 1, 2021): 013. http://dx.doi.org/10.1088/1475-7516/2021/09/013.

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Sakamoto, Hina, Kyungjin Ahn, Kiyotomo Ichiki, Hyunjin Moon, and Kenji Hasegawa. "Probing the Early History of Cosmic Reionization by Future Cosmic Microwave Background Experiments." Astrophysical Journal 930, no. 2 (May 1, 2022): 140. http://dx.doi.org/10.3847/1538-4357/ac6668.

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Abstract Cosmic reionization imprints its signature on the temperature and polarization anisotropies of the cosmic microwave background (CMB). Advances in CMB telescopes have already placed a significant constraint on the history of reionization. As near-future CMB telescopes target the maximum sensitivity, or observations limited only by the cosmic variance (CV), we hereby forecast the potential of future CMB observations in constraining the history of reionization. In this study, we perform Markov Chain Monte Carlo analysis for CV-limited E-mode polarization observations such as the Lite (Light) satellite for the studies of B-mode polarization and Inflation from cosmic background Radiation Detection (LiteBIRD), based on a few different methods that vary in the way of sampling reionization histories. We focus especially on estimating the very early history of reionization that occurs at redshifts z > 15, which is quantified by the partial CMB optical depth due to free electrons at z > 15, τ z>15. We find that reionization with τ z>15 ∼ 0.008, which is well below the current upper limit τ z>15 ∼ 0.02, is achievable by reionization models with minihalo domination in the early phase and can be distinguished from those with τ z>15 ≲ 5 × 10−4 through CV-limited CMB polarization observations. An accurate estimation of τ z>15, however, remains somewhat elusive. We investigate whether resampling the E-mode polarization data with limited spherical-harmonic modes may resolve this shortcoming.

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Remazeilles, Mathieu, Aditya Rotti, and Jens Chluba. "Peeling off foregrounds with the constrained moment ILC method to unveil primordial CMB B modes." Monthly Notices of the Royal Astronomical Society 503, no. 2 (March 5, 2021): 2478–98. http://dx.doi.org/10.1093/mnras/stab648.

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ABSTRACT Galactic foregrounds are the main obstacle to observations of the cosmic microwave background (CMB) B-mode polarization. In addition to obscuring the inflationary B-mode signal by several orders of magnitude, Galactic foregrounds have non-trivial spectral signatures that are partially unknown and distorted by averaging effects along the line of sight, within the pixel/beam window, and by various analysis choices (e.g. spherical harmonic transforms and filters). Statistical moment expansion methods provide a powerful tool for modelling the effective Galactic foreground emission resulting from these averaging effects in CMB observations, while blind component separation treatments can handle unknown foregrounds. In this work, we combine these two approaches to develop a new semiblind component separation method at the intersection of parametric and blind methods, called constrained moment ILC (cMILC). This method adds several constraints to the standard ILC method to deproject the main statistical moments of the Galactic foreground emission. Applications to maps are performed in needlet space and when compared to the NILC method, this helps in significantly reducing residual foreground contamination (bias, variance, and skewness) in the reconstructed CMB B-mode map, power spectrum, and tensor-to-scalar ratio. We consider sky simulations for experimental settings similar to those of LiteBIRD and PICO, illustrating which trade-offs between residual foreground biases and degradation of the constraint on r can be expected within the new cMILC framework. We also outline several directions that require more work in preparation for the coming analysis challenges.

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Gimeno-Amo, C., R. B. Barreiro, E. Martínez-González, and A. Marcos-Caballero. "Hemispherical power asymmetry in intensity and polarization for Planck PR4 data." Journal of Cosmology and Astroparticle Physics 2023, no. 12 (December 1, 2023): 029. http://dx.doi.org/10.1088/1475-7516/2023/12/029.

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Abstract One of the foundations of the Standard Model of Cosmology is statistical isotropy, which can be tested, among other probes, through the study of the Cosmic Microwave Background (CMB). However, a hemispherical power asymmetry on large scales has been reported for WMAP and Planck data by different works. The statistical significance is above 3σ for temperature, suggesting a directional dependence of the local power spectrum, and thus a feature beyond the ΛCDM model. With the third release of the Planck data (PR3), a new analysis was performed including the E-mode polarization maps, finding an asymmetry at a modest level of significance. In this work, we perform an asymmetry analysis in intensity and polarization maps for the latest Planck processing pipeline (PR4). We obtain similar results to those obtained with PR3, with a slightly lower significance (2.8% for the Sevem method) for the amplitude of the E-mode local variance dipole as well as a significant variability with the considered mask. In addition, a hint of a possible T-E alignment between the asymmetry axes is found at the level of ∼ 5%. For the analysis, we have implemented an alternative inpainting approach in order to get an accurate reconstruction of the E-modes. More sensitive all-sky CMB polarization data, such as those expected from the future LiteBIRD experiment, are needed to reach a more robust conclusion on the possible existence of deviations from statistical isotropy in the form of a hemispherical power asymmetry.

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Chandra, Debabrata, and Supratik Pal. "Investigating the constraints on primordial features with future cosmic microwave background and galaxy surveys." Journal of Cosmology and Astroparticle Physics 2022, no. 09 (September 1, 2022): 024. http://dx.doi.org/10.1088/1475-7516/2022/09/024.

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Abstract In this article, we do a thorough investigation of the competency of the forthcoming Cosmic Microwave Background (CMB) and Galaxy surveys in probing the features in the primordial power spectrum. Primordial features are specific model-dependent corrections on top of the standard power-law inflationary power spectrum; the functional form being given by different inflationary scenarios. Signature of any significant departure from the feature-less power spectrum will enable us to decipher the intricacies of the inflationary Universe. Here, we delve into three major yet distinct features, namely, Bump feature, Sharp feature signal, and Resonance feature signal. To analyse the features, we adopt a specific template for each feature model. We estimate the possible constraints on the feature parameters by employing Fisher matrix forecast analysis for the upcoming CMB missions such as CMB-S4, CORE-M5, LiteBIRD, PICO conjointly with DESI, and EUCLID galaxy surveys. To this end, we make use of four distinct observations to forecast on the bounds on the model parameters, namely, CMB, Baryon Acoustic Oscillations (BAO), Galaxy Clustering and Gravitational Weak Lensing or Cosmic Shear and their permissible synergy. For large scale structure (LSS) information, we consider different upper limits of scale for different redshifts for the purpose of circumventing the propagation of the errors stemming from the uncertainties on nonlinear scales into the constraints on the feature parameters. A comparative analysis of all three features has been done to estimate relative capabilities of these upcoming observations in shedding light on this crucial aspect of precision cosmology.

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Greco, Alessandro, Nicola Bartolo, and Alessandro Gruppuso. "Cosmic birefrigence: cross-spectra and cross-bispectra with CMB anisotropies." Journal of Cosmology and Astroparticle Physics 2022, no. 03 (March 1, 2022): 050. http://dx.doi.org/10.1088/1475-7516/2022/03/050.

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Abstract Parity-violating extensions of Maxwell electromagnetism induce a rotation of the linear polarization plane of photons during propagation. This effect, known as cosmic birefringence, impacts on the Cosmic Microwave Background (CMB) observations producing a mixing of E and B polarization modes which is otherwise null in the standard scenario. Such an effect is naturally parametrized by a rotation angle which can be written as the sum of an isotropic component α 0 and an anisotropic one δα(n̂). In this paper we compute angular power spectra and bispectra involving δα and the CMB temperature and polarization maps. In particular, contrarily to what happens for the cross-spectra, we show that even in absence of primordial cross-correlations between the anisotropic birefringence angle and the CMB maps, there exist non-vanishing three-point correlation functions carrying signatures of parity-breaking physics. Furthermore, we find that such angular bispectra still survive in a regime of purely anisotropic cosmic birefringence, which corresponds to the conservative case of having α o = 0. These bispectra represent an additional observable aimed at studying cosmic birefringence and its parity-violating nature beyond power spectrum analyses. They provide also a way to perform consistency checks for specific models of cosmic birefringence. Moreover, we estimate that among all the possible birefringent bispectra,〈δαTB〉and〈δαEB〉are the ones which contain the largest signal-to-noise ratio. Once the cosmic birefringence signal is taken to be at the level of current constraints, we show that these bispectra are within reach of future CMB experiments, as LiteBIRD.

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Basu, Aritra, Dominik J. Schwarz, Hans-Rainer Klöckner, Sebastian von Hausegger, Michael Kramer, Gundolf Wieching, and Blakesley Burkhart. "CMB foreground measurements through broad-band radio spectro-polarimetry: prospects of the SKA-MPG telescope." Monthly Notices of the Royal Astronomical Society 488, no. 2 (June 20, 2019): 1618–34. http://dx.doi.org/10.1093/mnras/stz1637.

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ABSTRACT Precise measurement of the foreground synchrotron emission, which contaminates the faint polarized cosmic microwave background (CMB) radiation, is a major challenge for the next-generation of CMB experiments. To address this, dedicated foreground measurement experiments are being undertaken at radio frequencies between 2 and 40 GHz. Foreground polarized synchrotron emission measurements are particularly challenging, primarily due to the complicated frequency dependence in the presence of Faraday rotation, and are best recovered through broad fractional-bandwidth polarization measurements at frequencies ≲5 GHz. A unique opportunity for measuring the foreground polarized synchrotron emission will be provided by the 15 m SKA-MPG telescope operating in the frequency range 1.7–3.5 GHz (S band). Here, we present the scope of a Southern-sky survey in S band at 1 deg angular resolution and explore its added advantage for application of powerful techniques, such as, Stokes Q, U fitting and RM-synthesis. A full Southern-sky polarization survey with this telescope, when combined with other on-going efforts at slightly higher frequencies, will provide an excellent frequency coverage for modelling and extrapolating the foreground polarized synchrotron emission to CMB frequencies (≳80 GHz) with rms brightness temperature better than 10 nK per 1 deg2. We find that this survey will be crucial for understanding the effects of Faraday depolarization, especially in low Galactic latitude regions. This will allow better foreground cleaning and thus will contribute significantly in further improving component separation analyses and increase usable sky area for cosmological analysis of the Planck data, and the LiteBIRD mission in the future.

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Patanchon, Guillaume, Hiroaki Imada, Hirokazu Ishino, and Tomotake Matsumura. "Effect of instrumental polarization with a half-wave plate on the B-mode signal: prediction and correction." Journal of Cosmology and Astroparticle Physics 2024, no. 04 (April 1, 2024): 074. http://dx.doi.org/10.1088/1475-7516/2024/04/074.

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Abstract:

Abstract We study the effect of incident unpolarized signal converted to polarized light produced by a realistic half-wave plate (HWP) and evaluate the impact of the effect in the measurement of Cosmic Microwave Background (CMB) B-mode polarization signal targeting to probe the tensor-to-scalar ratio r. The HWP is modeled with the Mueller formalism, and coefficients are decomposed for any incident angle into harmonics of the HWP rotation frequency due to azimuthal angle dependence. Although we use a general formalism, band-averaged matrix coefficients are calculated as an example for a 9-layer sapphire HWP using EM propagation simulations. We perform simulations of multi-detector observations in a band centered at 140 GHz using LiteBIRD instrumental configuration. We show both theoretically and with the simulations that most of the artefacts on Stokes parameter maps are produced by the dipole leakage on B-modes induced by the fourth harmonics MQI (4f) and MUI (4f). The resulting effect is strongly linked to the spin-2 focal plane scanning cross linking parameters. We develop a maximum likelihood-based method to correct the IP leakage by joint fitting of the Mueller matrix coefficients as well as the Stokes parameter maps. We show that the residual leakage after correction leads to an additional noise limited uncertainty on r of the order of 10-7, independently of the value of the Mueller matrix coefficients. We discuss the impact of the monopole signal and the potential coupling with other systematic effects such as gain variations and detector nonlinearities.

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