Dark Matter “Conspiracy” Unfolds As New Research Challenges Long-Standing Assumptions – The Debrief

Reversing decades of confusion about a potential “conspiracy” between dark matter and stellar matter, researchers are rethinking key assumptions underlying space data.

Scientists have long been puzzled by the surprisingly similar density of matter observed in many galaxies despite small variations. Now, new research suggests that oversimplified models and possible measurement errors may be at the root.

The Dark Matter Conspiracy in Question

The “bulge-halo conspiracy” refers to the puzzling observation that the density of matter at the center of the galaxy, or “bulge,” and its outer edge, or “halo,” appear to be decreasing at similar rates.

“This homogeneity suggested that dark matter and stars must somehow compensate for each other to form such regular mass structures,’ said Dr. Caro Derkenne, the lead author of -author of a new study that addresses the observations.

However, the exact nature of this relationship has remained elusive. Previous theories speculated that the poorly understood interaction between dark matter and baryonic matter could explain this phenomenon.

New Models of Galactic Density

Dr. Derkenne, an early-career researcher who leads an international team based in Australia, the UK, Austria, and Germany, led the study. Supported by the ARC Center of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), the team used data from the Middle Ages Galaxy Properties with Integral field spectroscopy (MAGPI) Survey, collected with the European Southern Observatory’s Very Large Telescope in Chile.

The team used this data to develop models based on Schwarzschild’s orbit, providing high-resolution insights extending up to three and a half light years in radius. These models offer detailed information on kinematics, three-dimensional shape, orbital structure, and dark matter fraction, allowing the team to investigate the internal mass distribution of galaxies as a way to probe the bulge. -halo conspiracy Of the 30 models developed, the study focused on 22.

“In the past, people built simple models that relied on a lot of simplifications and assumptions.” said Dr. Derkenne, highlighting the limitations of previous models. “Galaxies are complex, and we need to model them flexibly, or we end up with inaccurate measurements. Our models were run on the OzStar supercomputer at Swinburne University, which uses the equivalent of approx. -about 8,000 hours of desktop computing time.”

Cracks in the Conspiracy Theory

According to Derkenne’s observations, for early models to support a dark matter “conspiracy,” two conditions must be true. First, the scatter in the total mass density slope must be smaller than or equal to the scatter in the stellar mass density slope. Second, the dark matter content must be related to the stellar density structure.

However, the total mass density is higher than the stellar mass density, and the half-light dark matter is not related to the stellar density slope. This contradicts previous studies that suggested such a relationship. The authors suggest that their findings are more reliable due to their use of stellar mass profiles rather than stellar light structures measured through an aperture. Further comparisons between the Schwarzschild and Jeans modeling methods revealed that assuming a power law density artificially reduced the scatter, which may have falsely supported the bulge-halo conspiracy theory. This suggests that the theory may be based on flawed data.

Wider Applications for Earth

Derkenne believes their research has implications beyond cosmic questions, potentially informing how we handle Earth-bound data challenges. “Astronomy gives you a good understanding of big data,” he explained. “The real world is messy, and we don’t always have all the data with us. No one will tell you whether you are right or wrong. You have to gather data and study it until you find something that works.”

ASTRO 3D Director Professor Emma Ryan-Weber emphasized the importance of global scientific collaboration, helping to develop new talent to tackle the problems of the future. “The MAGPI project is a great example of how ASTRO 3D’s training workshops and collaborative spaces have leveraged Australia’s strategic partnership with the European Southern Observatory,” he said. “The complex data from the ESO Very Large Telescope not only addressed a long-standing problem in astronomy but also provided a platform for young scientists like Dr. Caro Derkenne to launch their careers and solve problems in real world.”

The study “The MAGPI Survey: Evidence Against the Bulge-Halo Conspiracy” come out of Monthly Notices of the Royal Astronomical Society on August 10, 2024.

Ryan Whalen covers science and technology for The Debrief. He holds a BA in History and a Master of Library and Information Science with a certificate in Data Science. He can be reached at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.