Cosmological Constraints on Interacting Dark Matter with SPT-3G D1

Models of the dark sector in which the dark matter participates in nontrivial interactions can create detectable signatures in cosmological observables, providing non-terrestrial means of probing the nature of dark matter. The new analysis still awaits peer review, but it already lays out the central claim clearly.

It is relevant because cosmology operates at the edge of what current instruments can measure, where systematic errors and model assumptions are never trivial. Small discrepancies between independent measurements have historically pointed toward missing physics rather than simple calibration errors, and the ongoing tension in the Hubble constant is a live example of how a persistent disagreement between methods can reshape the theoretical landscape. Each new dataset that approaches this territory with independent systematics adds real information to a problem that has resisted easy resolution for more than a decade. In this work, we test dark matter-baryon scattering, dark matter-dark radiation interactions, and dark matter annihilation using measurements of the CMB and BAO. We leverage the latest SPT-3G D1 CMB measurements of the primary anisotropies, alongside the D1 MUSE lensing data, to set up-to-date bounds on these models.

From the combination of Planck. The improved sensitivity to the first two models is in particular driven by the precision measurements of CMB lensing at small scales provided by SPT-3G D1 MUSE lensing data.

For annihilating dark matter, due to the degeneracy of the effect with the optical depth to reionization, we observe a non-trivial relationship between the upper bound on. When combining CMB data with the latest measurements from the Dark Energy Spectroscopic Instrument (DESI), upper bounds on extended model parameters can appear to tighten as the.

Future CMB and BAO measurements will provide better clarity on reconciling this discrepancy and enhance our ability to test dark matter interactions. Both individuals and organizations that work with arXivLabs have embraced and accepted our values of openness, community, excellence, and user data privacy.

The relevance goes beyond one dataset because even small shifts in measured parameters can matter when the field is testing the limits of the standard cosmological model. The Lambda-CDM framework describes the observable universe with remarkable economy, but its success rests on two components, dark matter and dark energy, whose physical nature remains entirely unknown. Any credible measurement that tightens or loosens the constraints on those components moves the entire theoretical enterprise forward, regardless of whether the immediate result looks dramatic on its own terms.

ArXiv is committed to these values and only works with partners that adhere to them. Have an idea for a project that will add value for arXiv's community.

Because this is still a preprint, the result should be read with genuine interest and proportionate caution. Peer review is not a guarantee of correctness, but it is a process that forces authors to respond to technical criticism from specialists who have no stake in a particular outcome. Preprints that survive that process, often with substantive revisions, emerge with a stronger evidential base than the version that first appeared. Until that stage is complete, the responsible reading keeps uncertainty explicitly visible rather than treating the claims as established findings.

The next step is to see whether the effect survives when independent surveys, different calibration strategies and tighter control of systematic uncertainties enter the picture. Programmes such as Euclid, DESI and the Rubin Observatory will deliver datasets over the next several years that cover the same parameter space with largely independent methods. If the current signal persists through those tests, its theoretical implications will become impossible to set aside. Until peer review and independent follow-up address those open questions, skepticism is not a failure of appreciation for the work; it is part of how science decides what to keep.

Source