Journal Article

On the equivalence between the effective cosmology and excursion set treatments of environment

Matthew C. Martino and Ravi K. Sheth

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 394, issue 4, pages 2109-2112
Published in print April 2009 | ISSN: 0035-8711
Published online April 2009 | e-ISSN: 1365-2966 | DOI:
On the equivalence between the effective cosmology and excursion set treatments of environment

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In studies of the environmental dependence of structure formation, the large-scale environment is often thought of as providing an effective background cosmology: for example the formation of structure in voids is expected to be just like that in a less dense universe with appropriately modified Hubble and cosmological constants. However, in the excursion set description of structure formation which is commonly used to model this effect, no explicit mention is made of the effective cosmology. Rather, this approach uses the spherical evolution model to compute an effective linear theory growth factor, which is then used to predict the growth and evolution of non-linear structures. We show that these approaches are, in fact, equivalent: a consequence of Birkhoff's theorem. We speculate that this equivalence will not survive in models where the gravitational force law is modified from an inverse square, potentially making the environmental dependence of clustering a good test of such models.

Keywords: methods: analytical; dark matter; large-scale structure of Universe

Journal Article.  2625 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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