The Quest for B Modes from Inflationary Gravitational Waves

2015/10/20 by Marc Kamionkowski, Ely D. Kovetz · 1 voice · 39 citations
Physics and Astronomy · #Black Holes and Theoretical Physics #Cosmology and Gravitation Theories #Pulsars and Gravitational Waves Research #astro-ph.CO #gr-qc #hep-ph #hep-th

paper · pdf · doi:10.1146/annurev-astro-081915-023433

45 pages, 11 figures; to appear in Annual Review of Astronomy and Astrophysics

arxiv created 2015/10/20 · openalex publication_date 2016/08/02 · arxiv updated 2016/10/05 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/29

Abstract

The search for the curl component (B mode) in the cosmic microwave background (CMB) polarization induced by inflationary gravitational waves is described. The canonical single-field slow-roll model of inflation is presented, and we explain the quantum production of primordial density perturbations and gravitational waves. It is shown how these gravitational waves then give rise to polarization in the CMB. We then describe the geometric decomposition of the CMB polarization pattern into a curl-free component (E mode) and curl component (B mode) and show explicitly that gravitational waves induce B modes. We discuss the B modes induced by gravitational lensing and by Galactic foregrounds and show how both are distinguished from those induced by inflationary gravitational waves. Issues involved in the experimental pursuit of these B modes are described, and we summarize some of the strategies being pursued. We close with a brief discussion of some other avenues toward detecting/characterizing the inflationary gravitational-wave background.

Citations

• Study of the Experimental Probe of Inflationary Cosmology (EPIC)-Intemediate Mission for NASA's Einstein Inflation Probe
• A new inflationary universe scenario: A possible solution of the horizon, flatness, homogeneity, isotropy and primordial monopole problems
• NINE-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE ( WMAP ) OBSERVATIONS: FINAL MAPS AND RESULTS
• Non-Gaussianity from Inflation: Theory and Observations
• Particle creation by black holes
• de Sitter vacua in string theory
• Planck 2015 results

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• First M87 Event Horizon Telescope Results. VIII. Magnetic Field Structure near The Event Horizon
• The Nanohertz Gravitational Wave Astronomer
• Gauge invariant perturbations of F(T,T_G) Cosmology
• BICEP / Keck XIII: Improved Constraints on Primordial Gravitational Waves using Planck, WMAP, and BICEP/Keck Observations through the 2018 Observing Season
• Fundamental physics opportunities with the next-generation Event Horizon Telescope
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• From South to North: Leveraging Ground-Based LATs for Full-Sky CMB Delensing and Constraints on r
• On the computational feasibility of Bayesian end-to-end analysis of LiteBIRD simulations within Cosmoglobe
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• ICE: a scalable, low-cost FPGA-based telescope signal processing and networking system
• Accurate and efficient likelihood modeling for large-scale CMB data
• Graviton mass constraint from CMB
• Synthetic Gravitational Waves from a Rolling Axion Monodromy
• Modified crossed Dragone optical design of the LiteBIRD low-frequency telescope
• Implications of pulsar timing arrays for Gauss-Bonnet Inflation
• Concept design of the LiteBIRD satellite for CMB B-mode polarization
• An introduction to the Planck mission
• Fermions and gravitational gyrotropy
• Visualisation of spherical harmonics in Peirce's quincuncial projection
• BB mode angular power spectrum of CMB from massive gravity
• Probing frequency-dependent half-wave plate systematics for CMB experiments with full-sky beam convolution simulations
• Establishing the origin of CMB B-mode polarization
• Cosmic Birefringence from Planck Data Release 4
• Probing the inflationary background of gravitational waves from large to small scales
• High-energy photon polarimeter for astrophysics
• Science with the TianQin Observatory: Preliminary results on Galactic double white dwarf binaries
• Mimicking features in alternatives to inflation with interacting spectator fields
• Measuring the spectrum of primordial gravitational waves with CMB, PTA and laser interferometers
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Discussions

• First, it's worth noting that the answer to this question is not simple or direct: it is not the case that gravitational waves directly polarize photons in the CMB. In one phase of the early Universe, [stackexchange, 6 points]

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• The Quest for Gravity Wave B-modes
• Is the Spectrum of Gravitational Waves the "Holy Grail" of Inflation?
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• Polarized CMB: Reionization and Primordial Tensor modes