Science & Technology

Astronomers Spot Unusual, Enormous Rings Around a Black Hole

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

This picture options a spectacular set of rings round a black gap, captured utilizing NASA’s Chandra X-ray Observatory and Neil Gehrels Swift Observatory. The X-ray pictures of the enormous rings reveal details about mud situated in our galaxy, utilizing a related precept to the X-rays carried out in physician’s places of work and airports.

The black gap is a part of a binary system referred to as V404 Cygni, situated about 7,800 mild years away from Earth. The black gap is actively pulling materials away from a companion star — with about half the mass of the Solar — into a disk across the invisible object. This materials glows in X-rays, so astronomers refer to those techniques as “X-ray binaries.”

On June 5, 2015, Swift found a burst of X-rays from V404 Cygni. The burst created the high-energy rings from a phenomenon often known as mild echoes. As a substitute of sound waves bouncing off a canyon wall, the sunshine echoes round V404 Cygni have been produced when a burst of X-rays from the black gap system bounced off of mud clouds between V404 Cygni and Earth. Cosmic mud shouldn’t be like family mud however is extra like smoke, and consists of tiny, strong particles.

On this composite picture, X-rays from Chandra (mild blue) have been mixed with optical knowledge from the Pan-STARRS telescope in Hawaii that present the celebs within the subject of view. The picture accommodates eight separate concentric rings. Every ring is created by X-rays from V404 Cygni flares noticed in 2015 that replicate off completely different mud clouds. (An artist’s illustration explains how the rings seen by Chandra and Swift have been produced. To simplify the graphic, the illustration exhibits solely 4 rings as a substitute of eight.)

The black gap in V404 Cygni is actively pulling materials away from a companion star — with about half the mass of the Solar — into a disk across the invisible object. A burst of X-rays from the black gap detected in 2015 created the high-energy rings from a phenomenon often known as mild echoes, the place mild bounces off of mud clouds in between the system and Earth. In these pictures, X-rays from Chandra are proven, together with optical knowledge from the Pan-STARRS telescope that depict the celebs within the subject of view. Every of the concentric rings is created by the burst of X-rays reflecting off mud clouds at completely different distances. The rings are proven incomplete, with gaps on the higher left, higher proper, and center areas. These gaps present the perimeters of Chandra’s subject of view throughout the observations, or the sections of the sphere Chandra didn’t observe. (Credit score: X-ray: NASA/CXC/U.Wisc-Madison/S. Heinz et al.; Optical/IR: Pan-STARRS)

A group of researchers led by Sebastian Heinz of the College 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 brilliant occasion that the operators of Chandra purposely positioned V404 Cygni in between the detectors in order that one other brilliant burst wouldn’t injury the instrument.

The rings inform astronomers not solely concerning the black gap’s conduct, but in addition concerning the panorama between V404 Cygni and Earth. For instance, the diameter of the rings in X-rays reveals the distances to the intervening mud clouds the sunshine ricocheted off. If the cloud is nearer to Earth, the ring seems to be bigger, and vice versa. The sunshine echoes seem as slender rings fairly than large rings or haloes as a result of the X-ray burst lasted solely a comparatively quick time frame.

This artist’s illustration exhibits intimately how the ringed construction seen by Chandra and Swift is produced. Every ring is brought on by X-rays bouncing off of various mud clouds. If the cloud is nearer to us, the ring seems to be bigger. The result’s a set of concentric rings with completely different obvious sizes relying on the gap of the intervening cloud from us. Credit score: Univ. of Wisconsin-Madison/S.Heinz

The researchers additionally used the rings to probe the properties of the mud clouds themselves. They in contrast the X-ray spectra — that’s, the brightness of X-rays over a vary of wavelengths — to pc fashions of mud with completely different compositions. Completely different compositions of mud will lead to completely different quantities of the decrease power X-rays being absorbed and prevented from being detected with Chandra. That is a related precept to how completely different components of our physique or our baggage soak up completely different quantities of X-rays, giving details about their construction and composition.

The group decided that the mud more than likely accommodates mixtures of graphite and silicate grains. As well as, by analyzing the interior rings with Chandra, they discovered that the densities of the mud clouds aren’t uniform in all instructions. Earlier research have assumed that they didn’t.

A paper describing the V404 Cygni outcomes was printed within the July 1, 2016, subject of The Astrophysical Journal (preprint). The authors of the research are Sebastian Heinz, Lia Corrales (College of Michigan); Randall Smith (Middle for Astrophysics | Harvard & Smithsonian); Niel Brandt (The Pennsylvania State College); Peter Jonker (Netherlands Institute for Area Analysis); Richard Plotkin (College of Nevada, Reno); and Joey Neilson (Villanova College).

This result’s associated to a related discovering of the X-ray binary Circinus X-1, which accommodates a neutron star fairly than a black gap, printed in a paper within the June 20, 2015, subject 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 research was additionally led by Sebastian Heinz.

There have been a number of papers printed yearly reporting research of the V404 Cygni outburst in 2015 that triggered these rings. Earlier outbursts have been recorded in 1938, 1956 and 1989, so astronomers should have a few years to proceed analyzing the 2015 one.

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

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