# Reconstructing the metric of the local Universe from number counts observations

## Abstract

Number counts observations available with new surveys such as the Euclid mission will be an important source of information about the metric of the Universe. We compute the low red-shift expansion for the energy density and the density contrast using an exact spherically symmetric solution in presence of a cosmological constant. At low red-shift the expansion is more precise than linear perturbation theory prediction. We then use the local expansion to reconstruct the metric from the monopole of the density contrast. We test the inversion method using numerical calculations and find a good agreement within the regime of validity of the red-shift expansion. The method could be applied to observational data to reconstruct the metric of the local Universe with a level of precision higher than the one achievable using perturbation theory.

- Authors:

- ICRANet, Piazza della Repubblica 10, I-65122 Pescara (Italy)
- Theoretical Physics Department, CERN, CH-1211 Geneva 23 (Switzerland)

- Publication Date:

- OSTI Identifier:
- 22667645

- Resource Type:
- Journal Article

- Resource Relation:
- Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2017; Journal Issue: 10; Other Information: Country of input: International Atomic Energy Agency (IAEA)

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCURACY; COMPUTERIZED SIMULATION; COSMOLOGICAL CONSTANT; DENSITY; DISTURBANCES; ENERGY DENSITY; EXPANSION; METRICS; PERTURBATION THEORY; RED SHIFT; SYMMETRY; UNIVERSE

### Citation Formats

```
Vallejo, Sergio Andres, and Romano, Antonio Enea, E-mail: antonio.enea.romano@cern.ch.
```*Reconstructing the metric of the local Universe from number counts observations*. United States: N. p., 2017.
Web. doi:10.1088/1475-7516/2017/10/023.

```
Vallejo, Sergio Andres, & Romano, Antonio Enea, E-mail: antonio.enea.romano@cern.ch.
```*Reconstructing the metric of the local Universe from number counts observations*. United States. doi:10.1088/1475-7516/2017/10/023.

```
Vallejo, Sergio Andres, and Romano, Antonio Enea, E-mail: antonio.enea.romano@cern.ch. Sun .
"Reconstructing the metric of the local Universe from number counts observations". United States.
doi:10.1088/1475-7516/2017/10/023.
```

```
@article{osti_22667645,
```

title = {Reconstructing the metric of the local Universe from number counts observations},

author = {Vallejo, Sergio Andres and Romano, Antonio Enea, E-mail: antonio.enea.romano@cern.ch},

abstractNote = {Number counts observations available with new surveys such as the Euclid mission will be an important source of information about the metric of the Universe. We compute the low red-shift expansion for the energy density and the density contrast using an exact spherically symmetric solution in presence of a cosmological constant. At low red-shift the expansion is more precise than linear perturbation theory prediction. We then use the local expansion to reconstruct the metric from the monopole of the density contrast. We test the inversion method using numerical calculations and find a good agreement within the regime of validity of the red-shift expansion. The method could be applied to observational data to reconstruct the metric of the local Universe with a level of precision higher than the one achievable using perturbation theory.},

doi = {10.1088/1475-7516/2017/10/023},

journal = {Journal of Cosmology and Astroparticle Physics},

number = 10,

volume = 2017,

place = {United States},

year = {Sun Oct 01 00:00:00 EDT 2017},

month = {Sun Oct 01 00:00:00 EDT 2017}

}