M87*, captured in all its glory in 2019.Handout/Getty Images News/Getty Images
Despite the activity, the shape of the black hole’s shadow itself, as well as its diameter, has remained consistent throughout the years, which is what Einstein’s Theory of General Relativity had predicted of a black hole of M87*’s size (6.5 billion times the mass of the Sun).
But the new observations suggest the surrounding crescent ring does vary over time, at a rate which previous models had not predicted before, according to the researchers.
The wobbling is good news for scientists, as it may allow them to probe the black hole’s accretion disc to an unprecedented level.
“The accretion flow contains matter than gets close enough to the black hole to allow us to observe the effects of strong gravity, and in some circumstances, allows us to test predictions from general relativity, like we’ve done in this study,” Wielgus said.
As astronomers continue to analyze a decade’s worth of observations taken of M87*, the data will not only allow them to understand this particular black hole better, but also give them valuable insights about the behavior of these behemoths across the vast universe.
Abstract: The Event Horizon Telescope (EHT) has recently delivered the first resolved images of M87*, the supermassive black hole in the center of the M87 galaxy. These images were produced using 230 GHz observations performed in 2017 April. Additional observations are required to investigate the persistence of the primary image feature—a ring with azimuthal brightness asymmetry—and to quantify the image variability on event horizon scales. To address this need, we analyze M87* data collected with prototype EHT arrays in 2009, 2011, 2012, and 2013. While these observations do not contain enough information to produce images, they are sufficient to constrain simple geometric models. We develop a modeling approach based on the framework utilized for the 2017 EHT data analysis and validate our procedures using synthetic data. Applying the same approach to the observational data sets, we find the M87* morphology in 2009–2017 to be consistent with a persistent asymmetric ring of ~40 μas diameter. The position angle of the peak intensity varies in time. In particular, we find a significant difference between the position angle measured in 2013 and 2017. These variations are in broad agreement with predictions of a subset of general relativistic magnetohydrodynamic simulations. We show that quantifying the variability across multiple observational epochs has the potential to constrain the physical properties of the source, such as the accretion state or the black hole spin.