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Strongly Coupled Dark Energy Cosmologies: preserving LCDM success and easing low scale problems I - Linear theory revisited
- Publication Year :
- 2015
-
Abstract
- In this first paper we discuss the linear theory and the background evolution of a new class of models we dub SCDEW: Strongly Coupled DE, plus WDM. In these models, WDM dominates today's matter density; like baryons, WDM is uncoupled. Dark Energy is a scalar field $\Phi$; its coupling to ancillary CDM, whose today's density is $\ll 1\, \%$, is an essential model feature. Such coupling, in fact, allows the formation of cosmic structures, in spite of very low WDM particle masses ($\sim 100$ eV). SCDEW models yields Cosmic Microwave Background and linear Large Scale features substantially undistinguishable from $\Lambda$CDM, but thanks to the very low WDM masses they strongly alleviate $\Lambda$CDM issues on small scales, as confirmed via numerical simulations in the II associated paper. Moreover SCDEW cosmologies significantly ease the coincidence and fine tuning problems of $\Lambda$CDM and, by using a field theory approach, we also outline possible links with inflationary models. We also discuss a possible fading of the coupling at low redshifts which prevents non linearities on the CDM component to cause computational problems. The (possible) low-$z$ coupling suppression, its mechanism, and its consequences are however still open questions -not necessarily problems- for SCDEW models. The coupling intensity and the WDM particle mass, although being extra parameters in respect to $\Lambda$CDM, are found to be substantially constrained a priori so that, if SCDEW is the underlying cosmology, we expect most data to fit also $\Lambda$CDM predictions.<br />Comment: 11 pages, 9 figures , accepted for publication on MNRAS; updated to match the published version; the companion paper can be found here http://arxiv.org/abs/1503.07867
- Subjects :
- Physics
Fine-tuning
Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Cosmic microwave background
Dark matter
Galaxies: evolution
Large-scale structure of universe
FOS: Physical sciences
Astronomy and Astrophysics
Astrophysics::Cosmology and Extragalactic Astrophysics
Galaxies: formation
Coupling (probability)
Cosmology
Theoretical physics
Space and Planetary Science
Dark energy
Field theory (psychology)
Darkmatter
Scalar field
Astrophysics - Cosmology and Nongalactic Astrophysics
Subjects
Details
- Language :
- English
- Database :
- OpenAIRE
- Accession number :
- edsair.doi.dedup.....050896188ba64544ef7f4c6bebe08a09