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Spherical collapse in quintessence models with zero speed of sound

Spherical collapse in quintessence models with zero speed of sound We study the spherical collapse model in the presence of quintessence with negligible speed of sound. This case is particularly motivated for w < 1 as it is required by stability. As pressure gradients are negligible, quintessence follows dark matter during the collapse. The spherical overdensity behaves as a separate closed FLRW universe, so that its evolution can be studied exactly. We derive the critical overdensity for collapse and we use the extended Press-Schechter theory to study how the clustering of quintessence affects the dark matter mass function. The effect is dominated by the modification of the linear dark matter growth function. A larger effect occurs on the total mass function, which includes the quintessence overdensities. Indeed, here quintessence constitutes a third component of virialized objects, together with baryons and dark matter, and contributes to the total halo mass by a fraction (1+w)Q/m. This gives a distinctive modification of the total mass function at low redshift. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Cosmology and Astroparticle Physics IOP Publishing

Spherical collapse in quintessence models with zero speed of sound

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References (47)

Copyright
Copyright © IOP Publishing Ltd
eISSN
1475-7516
DOI
10.1088/1475-7516/2010/03/027
Publisher site
See Article on Publisher Site

Abstract

We study the spherical collapse model in the presence of quintessence with negligible speed of sound. This case is particularly motivated for w < 1 as it is required by stability. As pressure gradients are negligible, quintessence follows dark matter during the collapse. The spherical overdensity behaves as a separate closed FLRW universe, so that its evolution can be studied exactly. We derive the critical overdensity for collapse and we use the extended Press-Schechter theory to study how the clustering of quintessence affects the dark matter mass function. The effect is dominated by the modification of the linear dark matter growth function. A larger effect occurs on the total mass function, which includes the quintessence overdensities. Indeed, here quintessence constitutes a third component of virialized objects, together with baryons and dark matter, and contributes to the total halo mass by a fraction (1+w)Q/m. This gives a distinctive modification of the total mass function at low redshift.

Journal

Journal of Cosmology and Astroparticle PhysicsIOP Publishing

Published: Mar 1, 2010

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