Orateur
Sonali VERMA
(Universite Libre de Bruxelles)
Description
In this talk [based on 2602.10078], I will show how measurements of the intergalactic medium (IGM) temperature from the Lyman-α forest can be used to constrain long-lived dark sector particles with lifetimes larger than 10¹⁶ s. Such particles deposit energy into the IGM through decays to Standard Model states, thereby modifying its late-time thermal history. I will also revisit constraints on these models from Planck measurements of the optical depth to reionization, and demonstrate that Lyman-α bounds provide a complementary window to those from the CMB. The resulting model-independent constraints can be reinterpreted across a wide range of decaying hidden-sector scenarios, including evaporating primordial black holes and dark photons.