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El Gordo's study suggests that dark matter may indeed be self-interacting, paving the way for an improved understanding of the universe
Recent research conducted by the Astrophysics and Cosmology group at Italy's International School for Advanced Studies (SISSA) has provided new insights into the mysterious properties of dark matter. Supercomputer simulations of "El Gordo," a massive merging cluster of galaxies located seven billion light-years away, suggest that dark matter may be self-interacting. This finding challenges the current standard cosmological model and offers a potential alternative by presenting a distinct signature of self-interacting dark matter (SIDM).
According to Riccardo Valdarnini, the author of the study, the prevailing standard model posits that dark matter is composed of cold, collisionless particles that only respond to gravity. However, this model fails to explain all observations. The SIDM model, which proposes that dark matter particles exchange energy through collisions, offers an alternative explanation. Proving the collisional properties of dark matter has been a challenging task.
Valdarnini and his team employed numerical simulations to investigate the behavior of dark matter within El Gordo. Their findings indicate that contrary to the predictions of the standard model, dark matter may indeed be self-interacting. Observations also revealed that dark matter centroids, the points of maximum density, undergo a physical separation from the other mass components in the cluster, providing a true "Signature of SIDM models."
While this research lends significant support to the SIDM model, it is important to note that the cross-section values of SIDM obtained from simulations currently exceed the present upper limits. This suggests that existing SIDM models are only a rough approximation and that the physical processes governing the interaction of dark matter in major cluster mergers are more complex than can be accurately represented by the commonly assumed approach based on the scattering of dark matter particles.
Overall, this significant advancement in our understanding of the universe holds promise for a deeper comprehension of dark matter properties and its potential impact on other aspects of astrophysics and cosmology that are yet to be uncovered.