Anisotropic non-gaussianity from rotational symmetry breaking excited initial states

Abstract

If the initial quantum state of the primordial perturbations broke rotational invariance, that would be seen as a statistical anisotropy in the angular correlations of the cosmic microwave background radiation (CMBR) temperature fluctuations. This can be described by a general parameterisation of the initial conditions that takes into account the possible direction-dependence of both the amplitude and the phase of particle creation during inflation. The leading effect in the CMBR twopoint function is typically a quadrupole modulation, whose coefficient is analytically constrained here to be |B| 0.06. The CMBR three-point function then acquires enhanced non-gaussianity, especially for the local configurations. In the large occupation number limit, a distinctive prediction is a modulation of the non-gaussianity around a mean value depending on the angle that short and long wavelength modes make with the preferred direction. The maximal variations with respect to the mean value occur for the configurations which are coplanar with the preferred direction and the amplitude of the non-gaussianity increases (decreases) for the short wavelength modes aligned with (perpendicular to) the preferred direction. For a high scale model of inflation with maximally pumped up isotropic occupation and 0.01 the difference between these two configurations is about 0.27, which could be detectable arXiv:1605.04758v3 [hep-th] 1 Dec 2016

Detecting higher spin fields through statistical anisotropy in the CMB and galaxy power spectra

“…The quadrupolar coefficients g 2M have been both theoretically and observationally well studied (see, e.g., Refs. [1,14,[39][40][41][42][44][45][46][47][48][49][50][51][52][53][54]. The latest limit |g 2M | 0.01 [1,48,55] (see also Ref.…”

Polypolar spherical harmonic decomposition of galaxy correlators in redshift space: Toward testing cosmic rotational symmetry

“…Such term may be related to e.g. supercurvature fluctuations in the inflationary era [6,7,59,60] or primordial non-Gaussianities [61][62][63][64][65]. Strictly speaking, this type of modulation also breaks statistical homogeneity.…”

Multitracing anisotropic non-Gaussianity with galaxy shapes

“…In [23], hereafter SCD15, we explored the potential of intrinsic alignments as a probe of inflation; in particular, through the scale-dependent bias in the statistics of intrinsic galaxy shapes that arises in the presence of anisotropic non-Gaussianity in the early universe. Constraints on this type of non-Gaussianity are inaccessible through two-point correlations of galaxy clustering, and they probe: primordial curvature perturbations generated by large-scale magnetic fields [26,27], the presence of higher spin (spin 2) fields during inflation [28][29][30][31][32], inflationary models with a generalized bispectrum from excited Bunch-Davies vacuum [33][34][35], vector fields [36][37][38][39] and solid inflation [40].…”