Astronomers Spot Unusual, Enormous Rings Around a Black Hole

V404 Cygni

V404 Cygni Rings (Credit: X-ray: NASA/CXC/U.Wisc-Madison/S. Heinz et al.; Optical/IR: Pan-STARRS)

  • Astronomers spotted an unusual set of rings in X-rays around a black hole with a companion star.
  • These rings are created by light echoes, a phenomenon similar to echoes on Earth from sound waves bouncing off hard surfaces.
  • NASA’s Chandra X-ray Observatory and Neil Gehrels Swift Observatory were used to detect X-rays ricocheting off dust clouds.
  • The rings provide information about the black hole, its companion, and the intervening dust clouds.

This image features a spectacular set of rings around a black hole, captured using NASA’s Chandra X-ray Observatory and Neil Gehrels Swift Observatory. The X-ray images of the giant rings reveal information about dust located in our galaxy, using a similar principle to the X-rays performed in doctor’s offices and airports.

The black hole is part of a binary system called V404 Cygni, located about 7,800 light years away from Earth. The black hole is actively pulling material away from a companion star — with about half the mass of the Sun — into a disk around the invisible object. This material glows in X-rays, so astronomers refer to these systems as “X-ray binaries.”

On June 5, 2015, Swift discovered a burst of X-rays from V404 Cygni. The burst created the high-energy rings from a phenomenon known as light echoes. Instead of sound waves bouncing off a canyon wall, the light echoes around V404 Cygni were produced when a burst of X-rays from the black hole system bounced off of dust clouds between V404 Cygni and Earth. Cosmic dust is not like household dust but is more like smoke, and consists of tiny, solid particles.

In this composite image, X-rays from Chandra (light blue) were combined with optical data from the Pan-STARRS telescope in Hawaii that show the stars in the field of view. The image contains eight separate concentric rings. Each ring is created by X-rays from V404 Cygni flares observed in 2015 that reflect off different dust clouds. (An artist’s illustration explains how the rings seen by Chandra and Swift were produced. To simplify the graphic, the illustration shows only four rings instead of eight.)

The black hole in V404 Cygni is actively pulling material away from a companion star — with about half the mass of the Sun — into a disk around the invisible object. A burst of X-rays from the black hole detected in 2015 created the high-energy rings from a phenomenon known as light echoes, where light bounces off of dust clouds in between the system and Earth. In these images, X-rays from Chandra are shown, along with optical data from the Pan-STARRS telescope that depict the stars in the field of view. Each of the concentric rings is created by the burst of X-rays reflecting off dust clouds at different distances. The rings are shown incomplete, with gaps at the upper left, upper right, and middle areas. These gaps show the edges of Chandra’s field of view during the observations, or the sections of the field Chandra did not observe. (Credit: X-ray: NASA/CXC/U.Wisc-Madison/S. Heinz et al.; Optical/IR: Pan-STARRS)

A team of researchers led by Sebastian Heinz of the University of Wisconsin in Madison analyzed 50 Swift observations of the system made in 2015 between June 30 and August 25, and Chandra observations made on July 11 and 25, 2015. It was such a bright event that the operators of Chandra purposely placed V404 Cygni in between the detectors so that another bright burst would not damage the instrument.

The rings tell astronomers not only about the black hole’s behavior, but also about the landscape between V404 Cygni and Earth. For example, the diameter of the rings in X-rays reveals the distances to the intervening dust clouds the light ricocheted off. If the cloud is closer to Earth, the ring appears to be larger, and vice versa. The light echoes appear as narrow rings rather than wide rings or haloes because the X-ray burst lasted only a relatively short period of time.

This artist’s illustration shows in detail how the ringed structure seen by Chandra and Swift is produced. Each ring is caused by X-rays bouncing off of different dust clouds. If the cloud is closer to us, the ring appears to be larger. The result is a set of concentric rings with different apparent sizes depending on the distance of the intervening cloud from us. Credit: Univ. of Wisconsin-Madison/S.Heinz

The researchers also used the rings to probe the properties of the dust clouds themselves. They compared the X-ray spectra — that is, the brightness of X-rays over a range of wavelengths — to computer models of dust with different compositions. Different compositions of dust will result in different amounts of the lower energy X-rays being absorbed and prevented from being detected with Chandra. This is a similar principle to how different parts of our body or our luggage absorb different amounts of X-rays, giving information about their structure and composition.

The team determined that the dust most likely contains mixtures of graphite and silicate grains. In addition, by analyzing the inner rings with Chandra, they found that the densities of the dust clouds are not uniform in all directions. Previous studies have assumed that they did not.

A paper describing the V404 Cygni results was published in the July 1, 2016, issue of The Astrophysical Journal (preprint). The authors of the study are Sebastian Heinz, Lia Corrales (University of Michigan); Randall Smith (Center for Astrophysics | Harvard & Smithsonian); Niel Brandt (The Pennsylvania State University); Peter Jonker (Netherlands Institute for Space Research); Richard Plotkin (University of Nevada, Reno); and Joey Neilson (Villanova University).

This result is related to a similar finding of the X-ray binary Circinus X-1, which contains a neutron star rather than a black hole, published in a paper in the June 20, 2015, issue of The Astrophysical Journal, titled, “Lord of the Rings: A Kinematic Distance to Circinus X-1 from a Giant X-Ray Light Echo” (preprint). This study was also led by Sebastian Heinz.

There have been multiple papers published every year reporting studies of the V404 Cygni outburst in 2015 that caused these rings. Previous outbursts were recorded in 1938, 1956 and 1989, so astronomers may still have many years to continue analyzing the 2015 one.

NASA’s Marshall Space Flight Center manages the Chandra program. The Smithsonian Astrophysical Observatory’s Chandra X-ray Center controls science from Cambridge, Massachusetts, and flight operations from Burlington, Massachusetts.


View Comments

  • Sýsþems ĺike these can be defìned bý space time.But preseñt phenomena of rinģ formation ìs beyònd the pervìew of space‐time to be explained.

  • These black holes are an illusion like looking at a piece of crome with dint causing a ring light and darkness around it. There is a warp in the galaxy or a pocket wave. We see illusions even here on earth. I don't believe planets are being compressed. Otherwise we would have be done a long time ago.

  • There are no such things as Black Holes! & if you still think they exist? Then see the work of Dr.Anthony Perrat Head Plasma Physicist at the USA National Lab. At Los Alamos! (Where they built & tested the A-Bomb!) & whose work was finished in 1994!
    Stop Lying! 2 stories about these stupid theories & Black Holes? Which "so massive even light cannot escape"..except when it does? The Universe is Electric & is Scalable! So if yer paying off a Student Loan for your Science Degrees? Sue them! They've known this since before 1900..Einstein's work was wrong! & he knew it before he got his Nobel Prize & even the prestige of the Nobel Cmmtte. & Laureates? More of an embarrassment to rec' one & try to live it down? Science isn't settled as we can tell if you read or hear the Govts.of the world telling you to Trust the Science & have faith in them? Why? It would seem that "trust & faith" for the Scientismist? Is required to be part of the most dangerous religion that has ever existed! Wake Up! ;Qxxx

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