In other words, they generated oceans of data relating to different possible explanations for their observations and looked at how predictive these simulated black hole environments were. This in turn enables evaluation of the design choices and imaging algorithms’ performance. The use of synthetic data enables quantitative evaluation of image reconstruction by comparison to the known ground truth. The synthetic data were carefully constructed to match properties of Sgr A* EHT measurements. To systematically explore and evaluate the imaging algorithms’ design choices and their effects on the resulting image reconstructions, we generated a series of synthetic data sets. So the researchers needed to use other methods to determine what shapes and phenomena best explained what little the could observe. From straight on it looks like a circle - but does that mean it’s a ball? A plate? A cylinder viewed end on? Here on Earth you might move your head or take a few steps to the side to get a little more info - but try doing that on a cosmic scale! To get effective parallax on a black hole 27,000 light-years away, you’d need to go quite a distance and probably break the laws of physics in the process. Think about viewing an ordinary object from a distance. (Note that the images here don’t simply show an image based on visible light, but the inferred shape based on countless readings of radiation and other measures.) But because this project really has no precedent (even the famous M87* image, though superficially similar, used different processes) it was necessary to essentially test multiple possibilities for how the same observations might have been made.įor instance, if it’s “dark” in the middle, is it because there’s something in the way (and there is - about half the galaxy) or because the hole itself has a hole (and it seems to)? The lack of direct observational data makes it hard to say. This means data from dozens of sources must be assembled and reconciled, itself an enormous task and a big part of why observations made in 2017 are only now being published as a final image, which you can see below. Instead, all kinds of other direct and indirect measurements of the object must be made - how radiation and gravity bend around it and so on. Black holes can’t be observed directly using something like the Hubble or even the still-warming-up Webb. Based on years of observations from around the globe, a huge team at over a hundred institutions managed to assemble an image of the black hole around which our galaxy rotates, despite its relative closeness and the interference from light-years worth of dust, nebulae and other vagaries of the void.īut this wasn’t just a matter of pointing the telescope in the right direction at the right time. If you haven’t read about this awesome science news yet, the Event Horizon Telescope’s own post is a great place to get the gist. But one aspect that hasn’t gotten quite as much attention is the central role played by simulations and synthetic data in the discovery. The researchers used Durham's DiRAC COSMA8 supercomputer to run hundreds of thousands of simulations of light travelling the same path, each time with a black hole of a different mass in the way.As countless science and general news outlets have reported today, the image of Sagittarius A*, the supermassive black hole at the center of our galaxy, is a fabulous scientific achievement. The Hubble pictures showed light from another galaxy behind Abell 1201 was reaching Earth in a way that indicated it was bending around an extremely massive object along the way - creating a "lensing" effect in which the more distant galaxy was both magnified and seemingly multiplied around a curved edge.Īstronomers believe every large galaxy has a black hole of at least supermassive size (more than 100,000 times the mass of the Sun) at its centre. Researchers from the United Kingdom's Durham University and Germany's Max Planck Institute discovered the black hole using an innovative technique combining supercomputer simulations with high-resolution pictures taken by the Hubble Space Telescope. The rare "ultramassive" black hole sits at the centre of Abell 1201, a supergiant elliptical galaxy residing in a galaxy cluster of the same name, about 2.7 billion light-years from Earth.
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