A Bound on the Dark-Sector Interaction Rate from Structure Formation
Year: 2026
Type: article
Abstract: Energy exchange between dark matter and dark energy changes the growth of structure, and published growth measurements therefore bound the exchange rate. This paper converts a coupling parametrised as a fraction of the Hubble rate times the dark-energy density into physical rates at several redshifts, and compares the transferred density over a Hubble time with the matter density that structure formation can tolerate losing or gaining. Couplings at the level sometimes quoted as interesting, a tenth of the Hubble rate, would move a substantial fraction of the matter density over cosmic time and are disfavoured in this simple accounting; couplings below about one hundredth of the Hubble rate move less than a few percent and remain compatible. The bound is stated as a rate in inverse seconds as well as a dimensionless coupling. Headline values are: rate at bound per s = 2.183e-20, coupling approx bound = 1.0e-02, fraction at coupling 0p1 = 2.172e-01, H0 per s = 2.183e-18. This study is simulated and computed from stated assumptions; it is not a measurement.
Author: Aldred, William Alexander
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7225803072
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