# Clustering fossil from primordial gravitational waves in anisotropic inflation

## Abstract

Inflationary models can correlate small-scale density perturbations with the long-wavelength gravitational waves (GW) in the form of the Tensor-Scalar-Scalar (TSS) bispectrum. This correlation affects the mass-distribution in the Universe and leads to the off-diagonal correlations of the density field modes in the form of the quadrupole anisotropy. Interestingly, this effect survives even after the tensor mode decays when it re-enters the horizon, known as the fossil effect. As a result, the off-diagonal correlation function between different Fourier modes of the density fluctuations can be thought as a way to probe the large-scale GW and the mechanism of inflation behind the fossil effect. Models of single field slow roll inflation generically predict a very small quadrupole anisotropy in TSS while in models of multiple fields inflation this effect can be observable. Therefore this large scale quadrupole anisotropy can be thought as a spectroscopy for different inflationary models. In addition, in models of anisotropic inflation there exists quadrupole anisotropy in curvature perturbation power spectrum. Here we consider TSS in models of anisotropic inflation and show that the shape of quadrupole anisotropy is different than in single field models. In fact, in these models, quadrupole anisotropy is projected into the preferred direction andmore »

- Authors:

- School of Physics, Institute for Research in Fundamental Sciences (IPM), P. O. Box 19395-5531, Tehran (Iran, Islamic Republic of)
- School of Astronomy, Institute for Research in Fundamental Sciences (IPM), P. O. Box 19395-5531, Tehran (Iran, Islamic Republic of)

- Publication Date:

- OSTI Identifier:
- 22525234

- Resource Type:
- Journal Article

- Journal Name:
- Journal of Cosmology and Astroparticle Physics

- Additional Journal Information:
- Journal Volume: 2015; Journal Issue: 10; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1475-7516

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ANISOTROPY; CORRELATION FUNCTIONS; CORRELATIONS; COSMOLOGICAL INFLATION; DENSITY; DISTURBANCES; ENERGY SPECTRA; FLUCTUATIONS; GALAXIES; GRAVITATIONAL WAVES; INFLATIONARY UNIVERSE; MASS DISTRIBUTION; PROBES; SCALARS; TENSORS; UNIVERSE

### Citation Formats

```
Emami, Razieh, and Firouzjahi, Hassan, E-mail: emami@ipm.ir, E-mail: firouz@ipm.ir.
```*Clustering fossil from primordial gravitational waves in anisotropic inflation*. United States: N. p., 2015.
Web. doi:10.1088/1475-7516/2015/10/043.

```
Emami, Razieh, & Firouzjahi, Hassan, E-mail: emami@ipm.ir, E-mail: firouz@ipm.ir.
```*Clustering fossil from primordial gravitational waves in anisotropic inflation*. United States. doi:10.1088/1475-7516/2015/10/043.

```
Emami, Razieh, and Firouzjahi, Hassan, E-mail: emami@ipm.ir, E-mail: firouz@ipm.ir. Thu .
"Clustering fossil from primordial gravitational waves in anisotropic inflation". United States. doi:10.1088/1475-7516/2015/10/043.
```

```
@article{osti_22525234,
```

title = {Clustering fossil from primordial gravitational waves in anisotropic inflation},

author = {Emami, Razieh and Firouzjahi, Hassan, E-mail: emami@ipm.ir, E-mail: firouz@ipm.ir},

abstractNote = {Inflationary models can correlate small-scale density perturbations with the long-wavelength gravitational waves (GW) in the form of the Tensor-Scalar-Scalar (TSS) bispectrum. This correlation affects the mass-distribution in the Universe and leads to the off-diagonal correlations of the density field modes in the form of the quadrupole anisotropy. Interestingly, this effect survives even after the tensor mode decays when it re-enters the horizon, known as the fossil effect. As a result, the off-diagonal correlation function between different Fourier modes of the density fluctuations can be thought as a way to probe the large-scale GW and the mechanism of inflation behind the fossil effect. Models of single field slow roll inflation generically predict a very small quadrupole anisotropy in TSS while in models of multiple fields inflation this effect can be observable. Therefore this large scale quadrupole anisotropy can be thought as a spectroscopy for different inflationary models. In addition, in models of anisotropic inflation there exists quadrupole anisotropy in curvature perturbation power spectrum. Here we consider TSS in models of anisotropic inflation and show that the shape of quadrupole anisotropy is different than in single field models. In fact, in these models, quadrupole anisotropy is projected into the preferred direction and its amplitude is proportional to g{sub *} N{sub e} where N{sub e} is the number of e-folds and g{sub *} is the amplitude of quadrupole anisotropy in curvature perturbation power spectrum. We use this correlation function to estimate the large scale GW as well as the preferred direction and discuss the detectability of the signal in the galaxy surveys like Euclid and 21 cm surveys.},

doi = {10.1088/1475-7516/2015/10/043},

journal = {Journal of Cosmology and Astroparticle Physics},

issn = {1475-7516},

number = 10,

volume = 2015,

place = {United States},

year = {2015},

month = {10}

}