TY - JOUR

T1 - Measuring Unified Dark Matter with 3D Cosmic Shear

AU - Camera, Stefano

AU - kitching, Thomas

AU - heavens, Alan

AU - Bertacca, Daniele

AU - Diaferio, Antonaldo

N1 - 12 pages, 5 figures; revisions on Fisher matrix analysis and Bayesian model selection according to the reviewer's comments; MNRAS (in press)

PY - 2010/2/25

Y1 - 2010/2/25

N2 - We present parameter estimation forecasts for future 3D cosmic shear surveys for a class of Unified Dark Matter (UDM) models, where a single scalar field mimics both Dark Matter (DM) and Dark Energy (DE). These models have the advantage that they can describe the dynamics of the Universe with a single matter component providing an explanation for structure formation and cosmic acceleration. A crucial feature of the class of UDM models we use in this work is characterised by a parameter, c_inf (in units of the speed of light c=1), that is the value of the sound speed at late times, and on which structure formation depends. We demonstrate that the properties of the DM-like behaviour of the scalar field can be estimated with very high precision with large-scale, fully 3D weak lensing surveys. We found that 3D weak lensing significantly constrains c_inf, and we find minimal errors 0.00003, for the fiducial value c_inf=0.001, and 0.000026, for c_inf=0.012. Moreover, we compute the Bayesian evidence for UDM models over the LCDM model as a function of c_inf. For this purpose, we can consider the LCDM model as a UDM model with c_inf=0. We find that the expected evidence clearly shows that the survey data would unquestionably favour UDM models over the LCDM model, for the values c_inf>0.001.

AB - We present parameter estimation forecasts for future 3D cosmic shear surveys for a class of Unified Dark Matter (UDM) models, where a single scalar field mimics both Dark Matter (DM) and Dark Energy (DE). These models have the advantage that they can describe the dynamics of the Universe with a single matter component providing an explanation for structure formation and cosmic acceleration. A crucial feature of the class of UDM models we use in this work is characterised by a parameter, c_inf (in units of the speed of light c=1), that is the value of the sound speed at late times, and on which structure formation depends. We demonstrate that the properties of the DM-like behaviour of the scalar field can be estimated with very high precision with large-scale, fully 3D weak lensing surveys. We found that 3D weak lensing significantly constrains c_inf, and we find minimal errors 0.00003, for the fiducial value c_inf=0.001, and 0.000026, for c_inf=0.012. Moreover, we compute the Bayesian evidence for UDM models over the LCDM model as a function of c_inf. For this purpose, we can consider the LCDM model as a UDM model with c_inf=0. We find that the expected evidence clearly shows that the survey data would unquestionably favour UDM models over the LCDM model, for the values c_inf>0.001.

KW - astro-ph.CO

UR - http://www.scopus.com/inward/record.url?scp=79960135407&partnerID=8YFLogxK

U2 - 10.1111/j.1365-2966.2011.18712.x

DO - 10.1111/j.1365-2966.2011.18712.x

M3 - Article

SN - 0035-8711

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

ER -