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For years, the Milky Way has been a cornerstone for scientists studying galaxy formation. However, recent studies suggest that our galaxy may not be as typical as once thought. Risa Wechsler, a professor of physics at Stanford University, emphasized the importance of comparing the Milky Way with similar galaxies to understand if it truly represents other galaxies in the universe.

Wechsler co-founded the Satellites Around Galactic Analogs (SAGA) Survey, which focuses on finding and analyzing galaxies akin to the Milky Way. The team has identified 101 such analogs after more than ten years of research. Their findings were published in three studies in The Astrophysical Journal on November 18.

"Our results show that we cannot constrain models of galaxy formation just to the Milky Way," Wechsler stated. She is also a professor at SLAC National Accelerator Laboratory and worked alongside Professor Marla Geha from Yale University and Yao-Yuan Mao from the University of Utah on these studies.

The research highlights that while ordinary atomic matter like hydrogen and iron constitutes about 15% of matter in the universe, dark matter makes up the remaining 85%. "No one knows what dark matter is made of," Wechsler said.

A primary aim of SAGA is to understand how dark matter halos affect galactic evolution by examining satellite galaxies orbiting larger host galaxies like ours. They discovered 378 satellite galaxies around these hosts using telescopic imaging techniques.

"There’s a reason no one ever tried this before," Wechsler remarked regarding their ambitious project. One study found that host galaxies with large satellites tend to have more satellites overall, yet our Milky Way hosts fewer than its peers.

Another study revealed differences in star formation among satellite galaxies. In most host systems, smaller satellites continue forming stars; however, only massive satellites like LMC and SMC form stars within our galaxy.

"Now we have a puzzle," Wechsler noted about why smaller satellites stopped forming stars within our system but continue elsewhere.

A third study led by Stanford's Yunchong "Richie" Wang calls for new models based partly on SAGA data comparing observations with computer simulations.

"SAGA provides a benchmark to advance our understanding through detailed study beyond just observing bright satellites," said Wechsler who directs Stanford’s Kavli Institute for Particle Astrophysics & Cosmology along with SLAC involvement funded by organizations including NSF & Heising-Simons Foundation plus Stanford support.

Marijane Leonard from Stanford School can be contacted via email marijane.leonard@stanford.edu for further media inquiries or information requests related specifically toward Humanities Sciences department activities thereon-campus locally here today!