Constraining dark matter decays with cosmic microwave background and weak lensing shear observations

Understand

From observations at low and high redshifts, it is well known that the bulk of dark matter (DM) has to be stable or at least very long-lived.

• However, the possibility that a small fraction of DM is unstable or that all DM decays with a half-life time ($\tau$) significantly longer than the age of the Universe is not ruled out.
• One-body decaying dark matter (DDM) consists of a minimal extension to the $\Lambda$CDM model.
• It causes a modification of the cosmic growth history as well as a suppression of the small-scale clustering signal, providing interesting consequences regarding the $S_8$ tension, which is the observed difference in the clustering amplitude between weak-lensing (WL) and cosmic microwave background (CMB) observations.