Decaying dark matter: simulations and weak-lensing forecast

Despite evidence for the existence of dark matter (DM) from very high and low redshifts, a moderate amount DM particle decay remains valid possibility. This includes both models with long-lived yet unstable particles or mixed scenarios where only small fraction is allowed to decay. In this paper, we investigate how decaying into radiation affect non-linear structure formation. We look at power spectrum its redshift evolution, varying lifetime ($\tau$) decaying-to-total ($f$), propose fitting function that reaches sub-percent precision below $k\sim10$ h/Mpc. Based on fit, perform forecast analysis Euclid-like weak lensing (WL) survey, including massive neutrino baryonic feedback parameters. find WL observations alone, it possible rule out lifetimes smaller than $\tau=75$ Gyr (at 95 percent CL) case all unstable. constraint improves $\tau=182$ if data combined CMB priors Planck satellite $\tau=275$ further assume be fully constrained by upcoming Sunyaev-Zeldovich X-ray data. The latter shows factor 3.2 improvement compared constraints alone. Regarding scenario strongly sub-component $\tau\sim 30$ lower, will $f>0.49$, $f>0.21$, $f>0.13$ same three scenarios. conclude stage-IV surveys allow us significantly improve current stability sector.