Tour: NASA's Chandra Breaks Down 'Treble Clef's' Galaxy Cluster Collision
(Credit: NASA/CXC/A. Hobart)
[Runtime: 03:05]

With closed-captions (at YouTube)

Astronomers have used NASA’s Chandra X-ray Observatory to break down the cause of a remarkable formation of radio waves they have nicknamed the “Treble Clef” because its distinct shape strongly resembles the musical symbol.

The research team figured out that an outburst from a supermassive black hole, followed by a collision of two galaxy clusters is the likely cause of the Treble Clef. Scientists want to know more about galaxy clusters because they are some of the largest structures in the universe, containing hundreds of individual galaxies and huge reservoirs of superheated gas.

It’s been particularly difficult to find an explanation for the Treble Clef because the cluster lies almost directly behind the plane of the Milky Way from the vantage point of Earth. This means that the stars, gas, and dust from our home galaxy largely block our view. However, by using telescopes like Chandra that can peer through the intervening material, a team of researchers was able to identify what is responsible for this uncommon clef-like structure.

The researchers used data Chandra and another X-ray telescope called eROSITA to uncover diffuse, hot gas at the location of the Treble Clef. This shows that a galaxy cluster hosts the unusually-shaped object in radio waves. The X-ray data also revealed that the Treble Clef is, in fact, located in two clusters in the process of merging.

After piecing all of the information together, the team concluded that the Treble Clef formed in a two-stage process. First, an outburst from supermassive black hole in the galaxy cluster’s center many millions of years ago drove clouds of charged particles and magnetic fields away at close to the speed of light. This led to a type of cosmic crescendo and initially produced bright radio waves that later faded as the particles lost energy. Next, there was a second act when the cloud became compressed or reenergized by the collision between the two clusters and became brighter again in radio waves. Shock waves — similar to the sonic booms from supersonic jets — from the collision may have played a role in this reenergizing process.

Of course, there isn’t really a giant treble clef in space. This is a case of pareidolia, the phenomenon when people see familiar shapes in random data, since there is no scientific connection to the musical notation. Other people have had other pareidolia reactions to this radio emission structure, seeing a dragon that is being viewed from the side. Whatever you see or don’t see in this image, astronomers have worked hard to find out what made it!

Quick Look: NASA's Chandra Breaks Down 'Treble Clef's' Galaxy Cluster Collision
(Credit: NASA/CXC/A. Hobart)
[Runtime: 00:46]

With narration (video above with voiceover)

Astronomers have discovered the source of a musically-themed shape in space.

The “Treble Clef” nickname comes from an unusual formation in radio waves.

Using NASA’s Chandra, scientists found it is the site of two colliding galaxy clusters.

The cosmic clef formed after a supermassive black hole erupted and the clusters collided.

Treble Clef or Dragon?
(Credit: NASA/CXC/A. Hobart)
[Runtime: 00:46]

The resemblance to a treble clef is a case of pareidolia, the phenomenon when people see familiar shapes in random data. A second interpretation of pareidolia for this radio emission structure is a dragon that is being viewed from the side.