It looks like a shooting target, but actually is an image of nested rings of X-ray light centered on an erupting black hole.
Above: Rings of X-ray light centered on V404 Cygni, a binary system containing an erupting black hole (dot at center), were imaged by the X-ray Telescope aboard NASA’s Swift satellite from June 30 to July 4. Credit: Andrew Beardmore (Univ. of Leicester) and NASA/Swift
Top image: The Swift X-ray image of V404 Cygni covers a patch of the sky equal to about half the apparent diameter of the full moon. This image shows the rings as they appeared on June 30. Credits: NASA’s Scientific Visualization Studio (left), Andrew Beardmore (Univ. of Leicester); NASA/Swift (right)
On June 15, NASA’s Swift satellite detected the start of a new outburst from V404 Cygni, where a black hole and a sun-like star orbit each other. Since then, astronomers around the world have been monitoring the ongoing light show.
On June 30, a team led by Andrew Beardmore at the University of Leicester, U.K., imaged the system using the X-ray Telescope aboard Swift, revealing a series concentric rings extending about one-third the apparent size of a full moon. A movie made by combining additional observations acquired on July 2 and 4 shows the expansion and gradual fading of the rings.
Astronomers say the rings result from an “echo” of X-ray light. The black hole’s flares emit X-rays in all directions. Dust layers reflect some of these X-rays back to us, but the light travels a longer distance and reaches us slightly later than light traveling a more direct path. The time delay creates the light echo, forming rings that expand with time.
Detailed analysis of the expanding rings shows that they all originate from a large flare that occurred on June 26 at 1:40 p.m. EDT. There are multiple rings because there are multiple reflecting dust layers between 4,000 and 7,000 light-years away from us. Regular monitoring of the rings and how they change as the eruption continues will allow astronomers to better understand their nature.
“The flexible planning of Swift observations has given us the best dust-scattered X-ray ring images ever seen. With these observations we can make a detailed study of the normally invisible interstellar dust in the direction of this black hole.”