Milky Way's own gravity can mimic dark matter clues, stellar stream simulations suggest

A new study from the University of Washington simulated stellar streams orbiting virtual host galaxies to test a theory about dark matter's influence. The results suggest that the host galaxy's gravity can mimic the effects of dark matter, potentially complicating efforts to distinguish between true dark matter signals and false positives. The study found that out of 15,000 simulated streams, only 70 remained perfectly smooth, indicating that the host galaxy's gravity is the primary cause of the irregularities. The simulations showed that the host galaxies alone caused the same kinds of irregularities observed in real stellar streams, which could help researchers isolate the effects of dark matter.

The study simulated four Milky Way-sized galaxies without dark matter clumps, and the resulting stellar streams showed significant irregularities. The simulations revealed that the host galaxies' gravitational structures created the same kinds of irregularities seen in real stellar streams, suggesting that the host galaxy's gravity is responsible for the observed patterns. This finding challenges the assumption that dark matter is the primary cause of the irregularities in stellar streams.

The results could help researchers better understand how dark matter influences the shape of stellar streams. The study found that the host galaxies' gravitational effects are significant enough to produce the same irregularities as dark matter. The findings suggest that future simulations could include dark matter clumps to further test the distinction between the effects of dark matter and the host galaxy's gravity. The study highlights the complexity of dark matter and the importance of studying stellar streams to uncover clues about the nature of dark matter.

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