The brightest galaxy in a cluster within the Perseus constellation looks like a fiery spiderweb, with filaments reaching out from a supermassive black hole at the center. Yet the violent storms at the heart of this galaxy do not appear to have disrupted the web of seemingly fragile wisps. This year, astronomers finally figured out how the gigantic galaxy, 10 times the size of the Milky Way, maintains its shape. The answer appeared in Hubble Space Telescope images showing fine threads within the filaments. Those threads indicate the presence of a magnetic field—1/10,000 the strength of Earth’s, but huge—that holds the structure together. The threads are created when powerful jets from the black hole drag cooler gases outward through space. “The black hole at the center is blowing enormous bubbles in the surrounding hot gas,” says Andrew Fabian, the University of Cambridge astronomer who led the study, which was published in Nature in August.
Fabian suspects that many young, elliptical galaxies have similar webs around them. “We think there are probably bubbles going all the time,” he says.