Cosmic acceleration and matter creation

We investigate the role of adiabatic matter creation in driving the current cosmic acceleration. We consider a phenomenological model in which the particles source has the form Psi=3betanH(0)(H/H-0)(alpha), where alpha and beta are dimensionless constants, n is the particle number density, and H-0 is the present value of the Hubble parameter. We introduce a cosmological constant in the model and use SNe Ia data to obtain confidence contours in the (Omega(m0), beta) plane for fixed values of alpha. We conclude that current SNe Ia data do not impose strong constraints on possible values of the parameter beta if we do not consider any information on Omega(m0). Assuming a Gaussian prior, such that Omega(m0)=0.27+/-0.06, the data now prefer values of beta close to zero, indicating that the particle creation mechanism is not favored to explain the cosmic acceleration. Finally, we simulate the data to be obtained with the proposed Supernova Acceleration Probe and estimate the constraints they will impose on beta.