Remarkably, Segue 1, an extremely faint dwarf galaxy, is positioned at the center of this image.
CDS, Strasbourg, France/CDS/Aladdin
Astoundingly, a supermassive black hole appears to reside at the heart of a nearby galaxy previously believed to be dominated by dark matter. Segue 1 is scarcely a galaxy, hosting merely around 1,000 stars compared to the Milky Way’s vast hundreds of billions. Yet, it seemingly contains a black hole with a mass approximately 10 times greater than the combined total of all its stars.
Segue 1 and similar dwarf galaxies lack sufficient stars to generate the gravitational force needed to hold them intact. To address this anomaly, physicists have long speculated that dark matter—a mysterious, invisible substance—fills the universe, contributing additional gravity.
Recently, Nathaniel Lujan and colleagues at the University of Texas at San Antonio began exploring computer models of Segue 1. They anticipated that the model yielding the best fit would be one characterized by dark matter. “After running hundreds of thousands of models, we were unable to find a viable solution,” Lujan remarks. “Eventually, we decided to experiment with the black hole mass, and that dramatically changed the results.”
The model that closely aligned with the observations of Segue 1 featured a black hole with a mass around 450,000 times that of the Sun. This discovery was particularly unexpected—not only due to the galaxy’s scarcity of stars but also considering its age. With so few stars, Segue 1 is estimated to have formed merely 400 million years following the universe’s initial star formation. Time constraints make it challenging for such a massive black hole to develop, especially since the much larger Milky Way likely consumed most of the gas that could have nourished Segue 1 shortly after its inception.
“This suggests there may be far more supermassive black holes than previously assumed,” Lujan states. If true, this could clarify some of the gravitational effects formerly attributed to dark matter, though it remains uncertain whether Segue 1 is typical of all dwarf galaxies. The quest for additional supermassive black holes continues.
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Source: www.newscientist.com
