Subjects: Physics >> The Physics of Elementary Particles and Fields submitted time 2016-05-09
Abstract： The possibility of reconstructing a spherically symmetric inhomogeneous Lemaitre-Tolman-Bondi (LTB) model with Lambda CDM observations has drawn much attention. Recently, an inhomogeneous LTB model having the same luminosity-distance and light-cone mass density of the homogeneous Lambda CDM model was reconstructed. From the Wilkinson microwave anisotropy probe 7-year measurements together with other cosmological observations, we calculate the cosmic age at our position in this LTB model, and obtain a constraint t(LTB) < 11.7 Gyr at 1 sigma confidence level. We find that this result is, although 2 Gyr younger compared with the age of the homogeneous Lambda CDM model, still within 1 sigma agreement with the constraint of cosmic age given by current astronomical measurements. We expect that in the future, with the help of more advanced observations, we can distinguish the reconstructed inhomogeneous LTB model from the homogeneous Lambda CDM model.
Peer Review Status:
Awaiting Review
Subjects: Physics >> The Physics of Elementary Particles and Fields submitted time 2016-05-09
Abstract： In this paper we investigate爐he爌ossible direct, non-gravitational爄nteraction燽etween爃olographic燿ark爀nergy�HDE) and燿ark爉atter. Firstly, we start with two simple models with爐he爄nteraction爐erms Q proportional to rho(dm) and Q proportional to rho(de), and then we move on to爐he爂eneral form Q proportional to rho(alpha)(m)rho(beta)(de).燭he燾osmological constraints爋f爐he爉odels are obtained from爐he爅oint analysis爋f爐he爌resent Union 2.1+BAO+CMB+H-0 data. We find that爐he燿ata slightly favor an爀nergy爁low from燿ark爉atter爐o燿ark爀nergy, although爐he爋riginal HDE model still lies in爐he�5.4% confidence level (CL) region. For all models we find c < 1 at爐he�5.4% CL. We show that compared with爐he燾osmic expansion,爐he爀ffect爋f爄nteraction爋n爐he爀volution爋frho(dm) and rho(de) is smaller, and爐he爎elative increment (decrement) amount爋f爐he爀nergy爄n爐he燿ark爉atter燾omponent is constrained to be less than 9% (15%) at爐he�5.4% CL. By introducing爐he爄nteraction, we find that even when c < 1爐he燽ig rip still can be avoided due to爐he爀xistence爋f燼 de Sitter solution at z -> -1. We show that this solution cannot be accomplished in爐he爐wo simple models, while for爐he爂eneral model such a solution can be achieved with a large beta, and爐he燽ig rip may be avoided at爐he�5.4% CL.
Peer Review Status:Awaiting Review
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