Publikationsdatum:
2015-08-24
Beschreibung:
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 ; its coupling to ancillary cold dark matter (CDM), whose today's density is 〈〈1 per cent, is an essential model feature. Such coupling, in fact, allows the formation of cosmic structures, in spite of very low WDM particle masses (~100 eV). SCDEW models yield cosmic microwave background and linear large scale features substantially undistinguishable from CDM, but thanks to the very low WDM masses they strongly alleviate CDM issues on small scales, as confirmed via numerical simulations in the second associated paper. Moreover SCDEW cosmologies significantly ease the coincidence and fine tuning problems of 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 CDM, are found to be substantially constrained a priori so that, if SCDEW is the underlying cosmology, we expect most data to fit also CDM predictions.
Print ISSN:
0035-8711
Digitale ISSN:
1365-2966
Thema:
Physik
