The Milky Way, our home galaxy, has long been depicted as a flat, spinning disk of dust, gas, and stars. However, recent findings by astronomers from the Center for Astrophysics | Harvard and Smithsonian (CfA) have shed light on its distinctive warped shape, suggesting that this warp may be due to an irregular halo of dark matter surrounding the galaxy.
This groundbreaking research, led by Jiwon Jesse Han, a Griffin Graduate School of Arts and Sciences student affiliated with the CfA, has provided compelling evidence pointing to the Milky Way's envelopment in an off-kilter halo of dark matter. This discovery not only offers a deeper understanding of our galaxy's evolution but also provides significant insights into the elusive nature of dark matter.
Dark matter, which makes up about 85% of the universe's matter content, remains one of the most significant mysteries in astrophysics. Although it doesn't interact with light, making it invisible, its presence can be inferred through its gravitational interactions and influence on visible matter.
The team's research suggests that the Milky Way's distinctive warp and flared edges, resembling a twisted frisbee, are a result of its envelopment in this tilted, football-shaped halo of dark matter. This halo extends beyond the galaxy's main disk and central nucleus, acting as the gravitational glue holding the galaxy together.
Building on previous work that deduced the stellar halo of the Milky Way as tilted and elliptically shaped, the team used computer models to calculate the orbits of stars within this tilted dark matter halo. The results were a near-perfect match to existing observations of the galaxy's warped shape.
Furthermore, these findings bolster the hypothesis that the Milky Way's current form is a result of past galactic collisions. "If the galaxy was just evolving on its own, it would have had this nice, spherical halo, this nice, flat disk," Han stated. The irregular shape of the halo suggests a history of galactic mergers and interactions.
Understanding the shape and properties of the dark matter halo surrounding the Milky Way could pave the way for new methods to study the mysterious substance. As Charlie Conroy, a faculty member at the CfA and in the Department of Astronomy, noted, "The fact that the galaxy is not spherical in our data implies that there is some limit to which dark matter can interact with itself."
In conclusion, this research not only reshapes our understanding of the Milky Way's structure but also offers a promising avenue for future studies into the nature and properties of dark matter.
