# Corrections to the apparent value of the cosmological constant due to local inhomogeneities

## Abstract

Supernovae observations strongly support the presence of a cosmological constant, but its value, which we will call apparent, is normally determined assuming that the Universe can be accurately described by a homogeneous model. Even in the presence of a cosmological constant we cannot exclude nevertheless the presence of a small local inhomogeneity which could affect the apparent value of the cosmological constant. Neglecting the presence of the inhomogeneity can in fact introduce a systematic misinterpretation of cosmological data, leading to the distinction between an apparent and true value of the cosmological constant. We establish the theoretical framework to calculate the corrections to the apparent value of the cosmological constant by modeling the local inhomogeneity with a ΛLTB solution. Our assumption to be at the center of a spherically symmetric inhomogeneous matter distribution correspond to effectively calculate the monopole contribution of the large scale inhomogeneities surrounding us, which we expect to be the dominant one, because of other observations supporting a high level of isotropy of the Universe around us. By performing a local Taylor expansion we analyze the number of independent degrees of freedom which determine the local shape of the inhomogeneity, and consider the issue of central smoothness, showingmore »

- Authors:

- Department of Physics, National Taiwan University, Taipei 10617, Taiwan, R.O.C. (China)

- Publication Date:

- OSTI Identifier:
- 22280227

- Resource Type:
- Journal Article

- Journal Name:
- Journal of Cosmology and Astroparticle Physics

- Additional Journal Information:
- Journal Volume: 2011; 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; ASTROPHYSICS; CORRECTIONS; COSMOLOGICAL CONSTANT; COSMOLOGY; DEGREES OF FREEDOM; ISOTROPY; MATHEMATICAL SOLUTIONS; ROUGHNESS; SMOOTH MANIFOLDS; SPHERICAL CONFIGURATION; SUPERNOVAE; UNIVERSE

### Citation Formats

```
Romano, Antonio Enea, and Chen, Pisin, E-mail: aer@phys.ntu.edu.tw, E-mail: pisinchen@phys.ntu.edu.tw.
```*Corrections to the apparent value of the cosmological constant due to local inhomogeneities*. United States: N. p., 2011.
Web. doi:10.1088/1475-7516/2011/10/016.

```
Romano, Antonio Enea, & Chen, Pisin, E-mail: aer@phys.ntu.edu.tw, E-mail: pisinchen@phys.ntu.edu.tw.
```*Corrections to the apparent value of the cosmological constant due to local inhomogeneities*. United States. doi:10.1088/1475-7516/2011/10/016.

```
Romano, Antonio Enea, and Chen, Pisin, E-mail: aer@phys.ntu.edu.tw, E-mail: pisinchen@phys.ntu.edu.tw. Sat .
"Corrections to the apparent value of the cosmological constant due to local inhomogeneities". United States. doi:10.1088/1475-7516/2011/10/016.
```

```
@article{osti_22280227,
```

title = {Corrections to the apparent value of the cosmological constant due to local inhomogeneities},

author = {Romano, Antonio Enea and Chen, Pisin, E-mail: aer@phys.ntu.edu.tw, E-mail: pisinchen@phys.ntu.edu.tw},

abstractNote = {Supernovae observations strongly support the presence of a cosmological constant, but its value, which we will call apparent, is normally determined assuming that the Universe can be accurately described by a homogeneous model. Even in the presence of a cosmological constant we cannot exclude nevertheless the presence of a small local inhomogeneity which could affect the apparent value of the cosmological constant. Neglecting the presence of the inhomogeneity can in fact introduce a systematic misinterpretation of cosmological data, leading to the distinction between an apparent and true value of the cosmological constant. We establish the theoretical framework to calculate the corrections to the apparent value of the cosmological constant by modeling the local inhomogeneity with a ΛLTB solution. Our assumption to be at the center of a spherically symmetric inhomogeneous matter distribution correspond to effectively calculate the monopole contribution of the large scale inhomogeneities surrounding us, which we expect to be the dominant one, because of other observations supporting a high level of isotropy of the Universe around us. By performing a local Taylor expansion we analyze the number of independent degrees of freedom which determine the local shape of the inhomogeneity, and consider the issue of central smoothness, showing how the same correction can correspond to different inhomogeneity profiles. Contrary to previous attempts to fit data using large void models our approach is quite general. The correction to the apparent value of the cosmological constant is in fact present for local inhomogeneities of any size, and should always be taken appropriately into account both theoretically and observationally.},

doi = {10.1088/1475-7516/2011/10/016},

journal = {Journal of Cosmology and Astroparticle Physics},

issn = {1475-7516},

number = 10,

volume = 2011,

place = {United States},

year = {2011},

month = {10}

}