# Searching for hidden mirror symmetries in CMB fluctuations from WMAP 7 year maps

## Abstract

We search for hidden mirror symmetries at large angular scales in the WMAP 7 year Internal Linear Combination map of CMB temperature anisotropies using global pixel based estimators introduced for this aim. Two different axes are found for which the CMB intensity pattern is anomalously symmetric (or anti-symmetric) under reflection with respect to orthogonal planes at the 99.84(99.96)% CL (confidence level), if compared to a result for an arbitrary axis in simulations without the symmetry. We have verified that our results are robust to the introduction of the galactic mask. The direction of such axes is close to the CMB kinematic dipole and nearly orthogonal to the ecliptic plane, respectively. If instead the real data are compared to those in simulations taken with respect to planes for which the maximal mirror symmetry is generated by chance, the confidence level decreases to 92.39(76.65)%. But when the effect in question translates into the anomalous alignment between normals to planes of maximal mirror (anti)-symmetry and these natural axes mentioned. We also introduce the representation of the above estimators in the harmonic domain, confirming the results obtained in the pixel one. The symmetry anomaly is shown to be almost entirely due to low multipoles,more »

- Authors:

- INAF/IASF-BO, Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna, via Gobetti 101, I-40129 Bologna (Italy)
- Laboratoire Astroparticule and Cosmologie (APC), CNRS, Université Paris Diderot, 10, rue A. Domon et L. Duquet, 75205 Paris Cedex 13 (France)
- Landau Institute for Theoretical Physics RAS, 119334 Moscow (Russian Federation)

- Publication Date:

- OSTI Identifier:
- 22280056

- Resource Type:
- Journal Article

- Journal Name:
- Journal of Cosmology and Astroparticle Physics

- Additional Journal Information:
- Journal Volume: 2012; Journal Issue: 07; 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; AXIAL SYMMETRY; COMPARATIVE EVALUATIONS; COSMOLOGY; DIPOLES; FLUCTUATIONS; GALAXIES; REFLECTION

### Citation Formats

```
Finelli, Fabio, Gruppuso, Alessandro, Paci, Francesco, and Starobinsky, Alexey A., E-mail: finelli@iasfbo.inaf.it, E-mail: gruppuso@iasfbo.inaf.it, E-mail: fpaci@apc.univ-paris7.fr, E-mail: alstar@landau.ac.ru.
```*Searching for hidden mirror symmetries in CMB fluctuations from WMAP 7 year maps*. United States: N. p., 2012.
Web. doi:10.1088/1475-7516/2012/07/049.

```
Finelli, Fabio, Gruppuso, Alessandro, Paci, Francesco, & Starobinsky, Alexey A., E-mail: finelli@iasfbo.inaf.it, E-mail: gruppuso@iasfbo.inaf.it, E-mail: fpaci@apc.univ-paris7.fr, E-mail: alstar@landau.ac.ru.
```*Searching for hidden mirror symmetries in CMB fluctuations from WMAP 7 year maps*. United States. doi:10.1088/1475-7516/2012/07/049.

```
Finelli, Fabio, Gruppuso, Alessandro, Paci, Francesco, and Starobinsky, Alexey A., E-mail: finelli@iasfbo.inaf.it, E-mail: gruppuso@iasfbo.inaf.it, E-mail: fpaci@apc.univ-paris7.fr, E-mail: alstar@landau.ac.ru. Sun .
"Searching for hidden mirror symmetries in CMB fluctuations from WMAP 7 year maps". United States. doi:10.1088/1475-7516/2012/07/049.
```

```
@article{osti_22280056,
```

title = {Searching for hidden mirror symmetries in CMB fluctuations from WMAP 7 year maps},

author = {Finelli, Fabio and Gruppuso, Alessandro and Paci, Francesco and Starobinsky, Alexey A., E-mail: finelli@iasfbo.inaf.it, E-mail: gruppuso@iasfbo.inaf.it, E-mail: fpaci@apc.univ-paris7.fr, E-mail: alstar@landau.ac.ru},

abstractNote = {We search for hidden mirror symmetries at large angular scales in the WMAP 7 year Internal Linear Combination map of CMB temperature anisotropies using global pixel based estimators introduced for this aim. Two different axes are found for which the CMB intensity pattern is anomalously symmetric (or anti-symmetric) under reflection with respect to orthogonal planes at the 99.84(99.96)% CL (confidence level), if compared to a result for an arbitrary axis in simulations without the symmetry. We have verified that our results are robust to the introduction of the galactic mask. The direction of such axes is close to the CMB kinematic dipole and nearly orthogonal to the ecliptic plane, respectively. If instead the real data are compared to those in simulations taken with respect to planes for which the maximal mirror symmetry is generated by chance, the confidence level decreases to 92.39(76.65)%. But when the effect in question translates into the anomalous alignment between normals to planes of maximal mirror (anti)-symmetry and these natural axes mentioned. We also introduce the representation of the above estimators in the harmonic domain, confirming the results obtained in the pixel one. The symmetry anomaly is shown to be almost entirely due to low multipoles, so it may have a cosmological and even primordial origin. Contrary, the anti-symmetry one is mainly due to intermediate multipoles that probably suggests its non-fundamental nature. We have demonstrated that these anomalies are not connected to the known issue of the low variance in WMAP observations and we have checked that axially symmetric parts of these anomalies are small, so that the axes are not the symmetry ones.},

doi = {10.1088/1475-7516/2012/07/049},

journal = {Journal of Cosmology and Astroparticle Physics},

issn = {1475-7516},

number = 07,

volume = 2012,

place = {United States},

year = {2012},

month = {7}

}