# CMB anisotropies generated by a stochastic background of primordial magnetic fields with non-zero helicity

## Abstract

We consider the impact of a stochastic background of primordial magnetic fields with non-vanishing helicity on CMB anisotropies in temperature and polarization. We compute the exact expressions for the scalar, vector and tensor part of the energy-momentum tensor including the helical contribution, by assuming a power-law dependence for the spectra and a comoving cutoff which mimics the damping due to viscosity. We also compute the parity-odd correlator between the helical and non-helical contribution which generate the TB and EB cross-correlation in the CMB pattern. We finally show the impact of including the helical term on the power spectra of CMB anisotropies up to multipoles with ℓ ∼ O(10{sup 3})

- Authors:

- DIFA, Dipartimento di Fisica e Astronomia, Alma Mater Studiorum, Università degli Studi di Bologna, viale Berti Pichat 6/2, I-40127 Bologna (Italy)
- INAF/IASF-BO, Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna, via Gobetti 101, I-40129 Bologna (Italy)

- Publication Date:

- OSTI Identifier:
- 22525243

- 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; ASTROPHYSICS; CORRELATIONS; DAMPING; ENERGY SPECTRA; ENERGY-MOMENTUM TENSOR; HELICITY; MAGNETIC FIELDS; MULTIPOLES; PARITY; POLARIZATION; RELICT RADIATION; SCALARS; STOCHASTIC PROCESSES; VECTORS; VISCOSITY

### Citation Formats

```
Ballardini, Mario, Finelli, Fabio, and Paoletti, Daniela, E-mail: ballardini@iasfbo.inaf.it, E-mail: finelli@iasfbo.inaf.it, E-mail: paoletti@iasfbo.inaf.it.
```*CMB anisotropies generated by a stochastic background of primordial magnetic fields with non-zero helicity*. United States: N. p., 2015.
Web. doi:10.1088/1475-7516/2015/10/031.

```
Ballardini, Mario, Finelli, Fabio, & Paoletti, Daniela, E-mail: ballardini@iasfbo.inaf.it, E-mail: finelli@iasfbo.inaf.it, E-mail: paoletti@iasfbo.inaf.it.
```*CMB anisotropies generated by a stochastic background of primordial magnetic fields with non-zero helicity*. United States. doi:10.1088/1475-7516/2015/10/031.

```
Ballardini, Mario, Finelli, Fabio, and Paoletti, Daniela, E-mail: ballardini@iasfbo.inaf.it, E-mail: finelli@iasfbo.inaf.it, E-mail: paoletti@iasfbo.inaf.it. Thu .
"CMB anisotropies generated by a stochastic background of primordial magnetic fields with non-zero helicity". United States. doi:10.1088/1475-7516/2015/10/031.
```

```
@article{osti_22525243,
```

title = {CMB anisotropies generated by a stochastic background of primordial magnetic fields with non-zero helicity},

author = {Ballardini, Mario and Finelli, Fabio and Paoletti, Daniela, E-mail: ballardini@iasfbo.inaf.it, E-mail: finelli@iasfbo.inaf.it, E-mail: paoletti@iasfbo.inaf.it},

abstractNote = {We consider the impact of a stochastic background of primordial magnetic fields with non-vanishing helicity on CMB anisotropies in temperature and polarization. We compute the exact expressions for the scalar, vector and tensor part of the energy-momentum tensor including the helical contribution, by assuming a power-law dependence for the spectra and a comoving cutoff which mimics the damping due to viscosity. We also compute the parity-odd correlator between the helical and non-helical contribution which generate the TB and EB cross-correlation in the CMB pattern. We finally show the impact of including the helical term on the power spectra of CMB anisotropies up to multipoles with ℓ ∼ O(10{sup 3})},

doi = {10.1088/1475-7516/2015/10/031},

journal = {Journal of Cosmology and Astroparticle Physics},

issn = {1475-7516},

number = 10,

volume = 2015,

place = {United States},

year = {2015},

month = {10}

}

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