A new study led by researchers at the University of California, Riverside, suggests that a different type of dark matter could explain several puzzling cosmic observations that have long challenged scientists.<\/p>\n
The research points to dense clumps of self-interacting dark matter as a single mechanism behind unusual structures seen across the universe.<\/p>\n
Dark matter makes up about 85% of all matter in the universe, yet it cannot be directly observed. <\/p>\n
The prevailing model treats it as cold and collisionless, meaning its particles pass through each other without interaction.<\/p>\n
While this framework works well on large scales, it struggles to explain certain dense and compact structures.<\/p>\n
The new work focuses on self-interacting dark matter, or SIDM, where particles collide and exchange energy. <\/p>\n
These interactions can trigger a process known as gravothermal collapse, forming tightly packed cores with extremely high densities.<\/p>\n
Each of these dense clumps can reach masses around a million times that of the Sun. <\/p>\n
According to the study, such objects could be responsible for a range of unexplained gravitational effects observed in different parts of the cosmos.<\/p>\n
One idea, three mysteries<\/p>\n
\u201cThe difference is like a crowd of people who ignore each other versus one where everyone is constantly bumping into one another,\u201d said Hai-Bo Yu. <\/p>\n
\u201cIn SIDM, these interactions can dramatically reshape the internal structure of dark matter halos.\u201d<\/p>\n
One example comes from the gravitational lens system JVAS B1938+666, where astronomers have detected a small but powerful distortion in the image of a distant galaxy. <\/p>\n
This \u201cpinch\u201d suggests the presence of an unseen dense object bending light through gravity.<\/p>\n
Another case is the GD-1 stellar stream, a long trail of stars within the Milky Way. The stream shows a gap and spur pattern, as if something invisible passed through it and disrupted its structure.<\/p>\n
The third example involves the Fornax 6 star cluster in the Fornax satellite galaxy. Its compact structure has been difficult to explain using conventional models, but a dense dark matter clump could act as a gravitational anchor, pulling stars together.<\/p>\n
Clumps reshape cosmic structure<\/p>\n
\u201cWhat\u2019s striking is that the same mechanism works in three completely different settings \u2014 across the distant universe, within our galaxy<\/a>, and in a neighboring satellite galaxy,\u201d Yu said. \u201cAll show densities that are difficult to reconcile with standard model dark matter but arise naturally in SIDM.\u201d<\/p>\n By linking these observations, the study offers a unified explanation for phenomena that previously required separate interpretations. Instead of invoking different processes for each case, SIDM provides a single framework that can account for them all.<\/p>\n The findings also highlight how small-scale interactions within dark matter<\/a> could play a larger role in shaping cosmic structures than previously thought. If confirmed, this could lead to revisions in how scientists model the formation and evolution of galaxies.<\/p>\n Beyond solving specific puzzles, the work opens new avenues for testing dark matter theories. Future observations of gravitational lenses, stellar streams, and satellite galaxies could help determine whether SIDM is a better fit than the traditional model.<\/p>\n