Chandra Explains the Treble Clef Cosmic Structure

Astronomers have found a likely explanation for one of the strangest shapes in the radio sky, a vast formation nicknamed the Treble Clef because it resembles the musical symbol. The Treble Clef cosmic structure stretches across more than two million light-years and lies about 1.55 billion light-years from Earth, in the direction of the constellation Camelopardalis. It had puzzled researchers for years, in part because it sits almost directly behind the plane of the Milky Way, where stars, gas and dust block much of the view from Earth. New work led by Andrea Botteon of the National Institute for Astrophysics in Italy, published in Astronomy and Astrophysics, brings the picture into focus.

Data from NASA’s Chandra X-ray Observatory and the German eROSITA telescope revealed diffuse, hot gas at the location of the Treble Clef, showing that a galaxy cluster hosts the object. The team also found that the cluster is in fact two clusters in the process of merging. The researchers concluded that the structure likely formed in two stages. First, a supermassive black hole at the centre of a galaxy expelled a cloud of charged particles. Later, a collision between the two galaxy clusters revived that material, stretching and shaping it into the form seen today.

What the Treble Clef cosmic structure reveals

The direct collision between the clusters probably happened a few hundred million years ago, and the clusters are now moving away from each other. The resemblance to a treble clef is a case of pareidolia, the tendency to see familiar shapes in random patterns, since there is no link to music in the physics. The result shows how black hole outbursts and cluster mergers can work together over enormous timescales to shape the radio sky. It also shows the power of combining radio and X-ray observations to study objects that visible light alone cannot reveal.

Source: Chandra X-ray Center