Black holes are famous for being invisible. So how do you measure a halo of hot gas wrapped around one about 6 billion light-years from Earth? Using a rare cosmic “double zoom”, astronomers directly measured the size of this corona and found that it stretches roughly as wide as our entire solar system.<\/p>\n\n\n\n
Led by Matus Rybak<\/a> at Leiden University<\/a>, the team studied the quasar RX J1131 with the Atacama Large Millimeter or submillimeter Array, or ALMA<\/a>. Their analysis, reported in a paper<\/a> in Astronomy & Astrophysics<\/em>, opens a new way to examine what happens right next to a supermassive black hole.<\/p>\n\n\n\n A black hole corona is a halo of extremely hot gas that clings to the region just outside the black hole, where swirling matter is heated to millions of degrees. It is a bit like the sun’s outer atmosphere, only far hotter and packed into a much smaller and more turbulent zone.<\/p>\n\n\n\n RX J1131<\/a> is a quasar, so its central black hole is actively feeding on gas and dust and shining as one of the brightest objects in the universe<\/a>. The new measurements show that its corona spans about 50 astronomical units, a scale similar to the distance from our Sun out to the edge of the solar system.<\/p>\n\n\n\n Between us and RX J1131 sits a massive galaxy roughly 4 billion light-years away whose gravity bends the quasar\u2019s light like a giant lens, splitting it into four separate images in the sky. This effect, known as strong gravitational lensing<\/a>, turns the foreground galaxy into a natural telescope that magnifies the background quasar and its surroundings.<\/p>\n\n\n\n Rybak and his colleagues reexamined data from the array taken nearly a decade earlier while they were hunting for cold gas in the system. <\/p>\n\n\n\n Small brightness changes in the four images did not match up, and they eventually realized that the galaxy acts like a big magnifying glass while its stars behave like many smaller ones, creating the double zoom that can reveal fine details near the black hole.<\/p>\n\n\n\n If the flickers had started near the black hole itself, all four lensed images would have brightened and dimmed together. <\/p>\n\n\n\nWhat astronomers saw around RX J1131<\/h2>\n\n\n\n
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How a rare double zoom in deep space works<\/h2>\n\n\n\n
Timing tiny flickers to map the halo<\/h2>\n\n\n\n