INTERACTION BETWEEN DARK ENERGY AND DARK MATTER: OBSERVATIONAL CONSTRAINTS FROM OHD, BAO, CMB AND SNe Ia

In order to test if there is energy transfer between dark energy (DE) and dark matter (DM), we investigate cosmological constraints on two forms of nontrivial interaction between the DM sector and the sector responsible for the acceleration of the universe, in light of the newly revised observations including OHD, CMB, BAO and SNe Ia. More precisely, we find the same tendencies for both phenomenological forms of the interaction term Q = 3 gamma H rho, i.e. the parameter gamma to be a small number, vertical bar gamma vertical bar approximate to 10(-2). However, concerning the sign of the interaction parameter, we observe that gamma > 0 when the interaction between dark sectors is proportional to the energy density of dust matter, whereas the negative coupling (gamma < 0) is preferred by observations when the interaction term is proportional to DE density. We further discuss two possible explanations to this incompatibility and apply a quantitative criteria to judge the severity of the coincidence problem. Results suggest that the gamma mIDE model with a positive coupling may alleviate the coincidence problem, since its coincidence index C is smaller than that for the gamma dIDE model, the interacting quintessence and phantom models by four orders of magnitude.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000329050700004&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Astronomy & AstrophysicsSCI(E)5ARTICLE14null2