The Cosmological Constraints On Unstable Dark Matter

The nature of dark matter is a hot issue of modern cosmology. If the dark matter particle could annihilate or decay, they may inject the extra energy into baryonic gas and vary their temperature and ionization, therefore unstable dark matter could affect the recombination and reionization process. These leave deeply imprints on the Cosmic Microwave Background(CMB): the large scale TE and EE power spectra is enhanced, and the small scale TT power spectrum is damped. Thus, we adopt the Markov Chain Monte Carlo(MCMC) technique to break the degeneracies among the cosmological parameters. We use WMAP three years data and also the SDSS and 2dF matter power spectra and other astronomical observations to put constraints on the annihilation or decay of dark matter. We also present the correlation between this extra effect and other cosmological parameters. Finally, we use the fisher matrix formalism to make the forecast on the future Planck satellite measurement.