In 2019, the Event Horizon Telescope (EHT) showed us the first images of M87 *, the supermassive black hole at the center of the giant elliptical galaxy Messier 87 located less than 53 million light-years away. Additional observations were required to investigate the persistence of the main image feature and quantify its variability using the M87 * data collected with the proto-EHT telescope array in 2009, 2011, 2012 and 2013. And this is where the mystery begins.
More secrets of the black hole
The stunning image of the silhouette of M87 * that opened a new chapter in astronomy last year, houses roughly the same mass as 6.5 billion suns. The analysis has revealed the behavior of the black hole image during this period, with its shadow characteristic, but also a variation in its orientation: the crescent that we see in it appears to be wobbling. Surrounding the shadow is a bright ring of radiation emitted by a rapidly moving, superheated gas that spins and falls into the jaws of M87 *. The ring is much brighter in its “lower” half, giving the feature a crescent-like appearance. That crescent is reeling.
“Last year we saw an image of the shadow of a black hole, which consists of a bright crescent formed by hot plasma revolving around M87 *, and a dark central part, where we expect the event horizon of the black hole to be.” , explains Maciek Wielgus of the Center for Astrophysics | Harvard & Smithsonian, in their study published in The Astrophysical Journal .
“But those results were based only on observations made during a one-week window in April 2017, which is too short to see much change. Based on last year’s results, we asked the following questions: is this morphology in the form of crescent with the file data? Would the file data indicate a similar size and orientation of the crescent? “
Extending the analysis to observations from 2009-2017, scientists have shown that M87 * adheres to theoretical expectations. The diameter of the black hole’s shadow has remained consistent with the prediction of Einstein’s theory of general relativity for a 6.5 billion solar mass black hole.
But although the diameter of the crescent remained constant, astronomers found that the data hid a surprise: the ring wobbles, thus revealing the dynamic structure of the accretion flow so close to the black hole’s event horizon, under conditions of gravity. extreme.
Why is this finding important?
Among other things, it will allow scientists to formulate new proofs of the theory of general relativity. And “because the flow of matter that falls on a black hole (which is heated to billions of degrees, ionizes and becomes tumultuous in the presence of magnetic fields), the crescent seems to oscillate over time,” he explains. Wielgus. “We actually see a lot of variation and not all theoretical accretion models allow for that much wobble. What it means is that we can start to discard some of the models based on the dynamics of the observed source. “
Researchers continue and will continue to make observations of the black hole next year, and they hope to obtain more data and even potentially create not only new images of M87, but also videos of how it changes over the days.
Referencia: Maciek Wielgus et al. 2020. Monitoring the Morphology of M87* in 2009-2017 with the Event Horizon Telescope. The Astrophysical Journal, 2020; 901 (1): 67 DOI: 10.3847/1538-4357/abac0d
