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Chemical and Kinetic Equilibrium in Cosmology: Facts and Myths
Stefano Profumo
https://arxiv.org/abs/2508.20988 https://arxiv.org/pdf/2508.20988

Chemical and Kinetic Equilibrium in Cosmology: Facts and Myths
We clarify that chemical and kinetic equilibration in the early Universe are distinct: neither implies the other, and the ordering of their decouplings need not be universal. We illustrate this with Standard-Model neutrino decoupling, strong-washout leptogenesis, dark-matter scenarios where kinetic decoupling precedes chemical freeze-out (resonant/forbidden, conversion/coannihilation, coscattering), and dark sectors at with temperatures distinct from the visible-sector temperature, with semi-an…

The Effect of Weak Cosmic Ray Heating Events on the Desorption of $\rm H_2$
O. Sipil\"a, K. Silsbee, N. Carbajal, P. Caselli, M. Padovani
https://arxiv.org/abs/2507.01612

The Effect of Weak Cosmic Ray Heating Events on the Desorption of $\rm H_2$
The typical amount of molecular hydrogen (${\rm H_2}$) in interstellar ices is not known, but significant freeze-out of ${\rm H_2}$ on dust grains is not expected. However, chemical models ubiquitously predict large amounts of $\rm H_2$ freeze-out in dense cloud conditions, and specialized treatments are needed to control the $\rm H_2$ population on grains. Here we present a numerical desorption model where the effect of weak heating events induced by cosmic rays (CRs) that heat grains to tempe…