Lyman-alpha Forest Constraints on Decaying Dark Matter

Understand

We present an analysis of high-resolution N-body simulations of decaying dark matter cosmologies focusing on the statistical properties of the transmitted Lyman-alpha forest flux in the high-redshift intergalactic medium.

• In this type of model a dark matter particle decays into a slightly less massive stable dark matter daughter particle and a comparably light particle.
• The small mass splitting provides a non-relativistic kick velocity V_k to the daughter particle resulting in free-streaming and subsequent damping of small-scale density fluctuations.
• Current Lyman-alpha forest power spectrum measurements probe comoving scales up to ~ 2-3 h^-1 Mpc at redshifts z ~ 2-4, providing one of the most robust ways to probe cosmological density fluctuations on relatively small scales.