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This artist\u2019s illustration depicts the findings of a new study about the\u00a0supermassive black hole\u00a0at the center of our galaxy called Sagittarius A* (abbreviated as Sgr A*). As reported in our\u00a0latest press release, this result found that Sgr A* is spinning so quickly that it is warping\u00a0spacetime\u00a0\u2014 that is, time and the three dimensions of space \u2014 so that it can look more like a football.<\/p>\n
These results were made with\u00a0NASA\u2019s Chandra X-ray Observatory\u00a0and the NSF\u2019s Karl G. Jansky Very Large Array (VLA). A team of researchers applied a new method that uses\u00a0X-ray\u00a0and\u00a0radio\u00a0data to determine how quickly Sgr A* is spinning based on how material is flowing towards and away from the\u00a0black hole. They found Sgr A* is spinning with an angular velocity that is about 60% of the maximum possible value, and with an\u00a0angular momentum\u00a0of about 90% of the maximum possible value.<\/p>\n
Black holes have two fundamental properties: their\u00a0mass\u00a0(how much they weigh) and their spin (how quickly they rotate). Determining either of these two values tells scientists a great deal about any black hole and how it behaves. In the past, astronomers made several other estimates of Sgr A*\u2019s rotation speed using different techniques, with results ranging from Sgr A* not spinning at all to it spinning at almost the maximum rate.<\/p>\n
The new study suggests that Sgr A* is, in fact, spinning very rapidly, which causes the spacetime around it to be squashed down. The illustration shows a cross-section of Sgr A* and material swirling around it in a disk. The black sphere in the center represents the so-called\u00a0event horizon\u00a0of the black hole, the point of no return from which nothing, not even light, can escape.<\/p>\n
Looking at the spinning black hole from the side, as depicted in this illustration, the surrounding spacetime is shaped like a football. The faster the spin the flatter the football.<\/p>\n
The yellow-orange material to either side represents gas swirling around Sgr A*. This material inevitably plunges towards the black hole and crosses the event horizon once it falls inside the football shape. The area inside the football shape but outside the event horizon is therefore depicted as a cavity. The blue blobs show\u00a0jets\u00a0firing away from the poles of the spinning black hole. Looking down on the black hole from the top, along the barrel of the jet, spacetime is a circular shape.<\/p>\n
A black hole\u2019s spin can act as an important source of energy. Spinning supermassive black holes produce collimated outflows such as jets when their spin energy is extracted, which requires that there is at least some matter in the vicinity of the black hole. Because of limited fuel around Sgr A*, this black hole has been relatively quiet in recent millennia with relatively weak jets. This work, however, shows that this could change if the amount of material in the vicinity of Sgr A* increases.<\/p>\n
To determine the spin of Sgr A*, the authors used an empirically based technique referred to as the \u201coutflow method\u201d that details the relationship between the spin of the black hole and its mass, the properties of the matter near the black hole, and the outflow properties. The collimated outflow produces the radio waves, while the disk of gas surrounding the black hole is responsible for the X-ray emission. Using this method, the researchers combined data from Chandra and the VLA with an independent estimate of the black hole\u2019s mass from other telescopes to constrain the black hole\u2019s spin.<\/p>\n
The paper describing these results led by Ruth Daly (Penn State University) is published in the January 2024 issue of the Monthly Notices of the Royal Astronomical Society and appears online at\u00a0 The other authors are Biny Sebastian (University of Manitoba, Canada), Megan Donahue (Michigan State University), Christopher O\u2019Dea (University of Manitoba), Daryl Haggard (McGill University) and Anan Lu (McGill University).<\/p>\n
NASA\u2019s Marshall Space Flight Center manages the Chandra program. The Smithsonian Astrophysical Observatory\u2019s Chandra X-ray Center controls science operations from Cambridge, Massachusetts, and flight operations from Burlington, Massachusetts.<\/p>\n
Read more from NASA\u2019s Chandra X-ray Observatory.<\/p>\n
For more Chandra images, multimedia and related materials, visit:<\/p>\n
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This artist\u2019s illustration shows a cross-section of Sagittarius A*, pronounced as \u201cSAJ-ee-TARE-ee-us A-star\u201d, the supermassive black hole near the center of our Milky Way galaxy.<\/p>\n
In the middle of the image, the spinning, circular black hole is presented from the side in black. The shape of the surrounding spacetime, pictured in shades of dark yellow, looks as though it has been squashed down, thus resembling the shape of an American football. The swirling gas that surrounds Sagittarius A* is presented on either side of the black hole, within a rectangular-shaped dotted line, indicating the representation is a cross-section view.<\/p>\n
The background of the image contains a multitude of faint stars, peeking out from within brooding, dark red, indistinct clouds.<\/p>\n
Megan Watzke
Chandra X-ray Center
Cambridge, Mass.
617-496-7998<\/p>\n
Jonathan Deal
Marshall Space Flight Center
Huntsville, Ala.
256-544-0034<\/p>\n<\/div>\n