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| This illustration shows a black hole’s corona, depicted as a purple haze above the bright inner accretion disk. While the disk would emit a blinding blue-white light, its brightness is toned down for contrast. The purple color represents X-ray emissions, invisible in regular light, and the warped disk realistically illustrates how the black hole’s gravity distorts our view. |
Recent findings from NASA’s Imaging X-ray Polarimetry Explorer (IXPE) mission have significantly advanced our understanding of black hole coronae, the superheated plasma regions surrounding these cosmic giants. While black holes are known for their intense gravitational pull, which prevents light from escaping, they are often encased in accretion disks—spirals of gas and debris—and may also produce relativistic jets, which are high-speed outflows of matter.
The corona around a black hole, akin to the Sun’s corona but at billions of degrees Fahrenheit, has long puzzled astrophysicists. Researchers have speculated about its shape and composition: is it a spherical structure, a byproduct of the accretion disk, or located near the jets?
IXPE, which specializes in measuring X-ray polarization, offers a novel way to examine these structures. By analyzing polarization data, scientists can infer the shape and dynamics of the corona and its connection to the accretion disk. “X-ray polarization provides a new way to examine black hole accretion geometry,” said Lynnie Saade, a postdoctoral researcher at NASA’s Marshall Space Flight Center and lead author of the study.
Data from IXPE’s observations of 12 black holes—including Cygnus X-1, Cygnus X-3, and several supermassive black holes—revealed that the corona is extended in the same direction as the accretion disk. This finding challenges previous models that depicted the corona as a “lamppost” structure above the disk.
Interestingly, IXPE’s observations suggest that both stellar-mass and supermassive black holes share similar accretion disk geometries despite their vastly different scales and feeding mechanisms. “Stellar-mass black holes rip mass from companion stars, while supermassive black holes consume everything around them,” noted Philip Kaaret, principal investigator for IXPE. This unexpected similarity may indicate that studying nearby stellar-mass black holes can illuminate the properties of more distant supermassive counterparts.
Saade emphasized the potential for further discoveries: “IXPE has provided the first opportunity in a long time for X-ray astronomy to reveal the underlying processes of accretion and unlock new findings about black holes.” The complete findings are published in the latest issue of The Astrophysical Journal.
The IXPE mission is a collaborative effort between NASA and the Italian Space Agency, with contributions from partners in 12 countries. Managed by Ball Aerospace, IXPE continues to deliver groundbreaking data that enhances our understanding of celestial phenomena, particularly the enigmatic behaviors of black holes.
