At linear order the only expected source of a curl-like, B mode, polarization pattern in the cosmic microwave background (CMB) is primordial gravitational waves. At second-order B modes are also produced from purely scalar, density, initial conditions. Unlike B modes from primordial gravitational waves, these B modes are expected to be non-Gaussian and not independent from the temperature and gradient-like polarization, E mode, CMB anisotropies. We find that the three point function between a second-order B mode and two first-order T/E modes is a powerful probe of second-order B modes and should be detectable by upcoming CMB experiments. We focus on the contribution to the three point function arising from non-linear evolution and scattering processes before the end of recombination as this provides new information on the universe at $z> 1000$. We find that this contribution can be separated from the other contributions and is measurable at $\sim 2.5 σ$ by CMB experiments with noise levels of $\sim 1 μ$Karcmin and delensing efficiencies $\ge 90\%$, such as the proposed PICO satellite. We show that approximately half of the total signal arises from non-linearly induced vector and tensor metric perturbations, as evaluated in the Newtonian gauge. This bispectrum is a unique probe of these perturbations in the CMB, as their contribution to the power spectrum is suppressed. An important feature of this bispectrum is that the detectability will increase with decreasing experimental noise, in the absence of primordial B modes, provided that delensing efficiencies improve in parallel.
One of the cornerstones of general relativity is the equivalence principle. However, the validity of the equivalence principle has only been established on solar system scales for standard matter fields; this result cannot be assumed to hold for the non-standard matter fields that dominate the gravitational dynamics on cosmological scales. Here we show how the equivalence principle may be tested on cosmological scales for non-standard matter fields using the odd multipoles of the galaxy cross-power spectrum and bispectrum. This test makes use of the imprint on the galaxy cross-power spectrum a…
Cross-correlation between CMB B-modes and Faraday Rotation as a Novel Probe of Primordial Magnetic Fields
Kavli IPMU (WPI), UTIAS, The University of Tokyo（木下浦和宇宙物理研究所（世界顶级学术前沿中心），多伦多大学天体物理与空间科学系，东京大学）；Department of Applied Mathematics and Theoretical Physics, University of Cambridge（剑桥大学应用数学与理论物理系）；Kavli Institute for Cosmology, University of Cambridge（剑桥大学卡弗里宇宙学研究所）
Constraining primordial non-Gaussianity and parity-violation through Scalar-Induced Gravitational Waves with next-generation ground-based interferometers
Università di Pisa（比萨大学）；Istituto Nazionale di Fisica Nucleare (INFN)（意大利国家核物理研究所）；Università degli Studi di Padova（帕多瓦大学）；Istituto Nazionale di Astrofisica (INAF)（意大利国家天体物理研究所）
Boosted Odds: Lower-Point Probes of Parity Violation with Momentum Fields
University of Cambridge（剑桥大学）；Kavli Institute for Cosmology Cambridge（剑桥卡弗里宇宙学研究所）；University of Oxford（牛津大学）；Ludwig-Maximilians-Universität（路德维希-马克西米利安大学（慕尼黑大学））；Institute of Astronomy, University of Cambridge（剑桥大学天文研究所）
Twisted echoes of an odd quartet: Scalar-induced gravitational waves as a probe of primordial parity-violation
Università degli Studi di Padova（帕多瓦大学）；Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Padova（意大利国家核物理研究所帕多瓦分部）；Istituto Nazionale di Astrofisica (INAF), Osservatorio Astronomico di Padova（意大利国家天体物理研究所帕多瓦天文台）
We study graviton non-Gaussianities in the EFT of Inflation. At leading (second) order in derivatives, the graviton bispectrum is fixed by Einstein gravity. There are only two contributions at third order. One of them breaks parity. They come from operators that directly involve the foliation: we then expect sizable non-Gaussianities in three-point functions involving both gravitons and scalars. However, we show that at leading order in slow roll the parity-odd operator does not modify these mixed correlators. We then identify the operators that can affect the graviton bispectrum at fourth ord…
We derive a set of no-go theorems and yes-go examples for the parity-odd primordial trispectrum of curvature perturbations. We work at tree-level in the decoupling limit of the Effective Field Theory of Inflation and assume scale invariance and a Bunch-Davies vacuum. We show that the parity-odd scalar trispectrum vanishes in the presence of any number of scalar fields with arbitrary mass and any parity-odd scalar correlator vanishes in the presence of any number of spinning fields with massless de Sitter mode functions, in agreement with the findings of Liu, Tong, Wang and Xianyu [1]. The same…
The Bispectrum of Intrinsic Alignments: II. Precision Comparison Against Dark Matter Simulations
Utrecht University（乌得勒支大学）；Max-Planck-Institut für Astrophysik（马克斯·普朗克天体物理学研究所）；The University of Tokyo（东京大学）；Universität Bonn（波恩大学）；Leiden University（莱顿大学）；Ruđer Bošković Institute（鲁德博什科维奇研究所）；University of Cambridge（剑桥大学）
