Galaxy changes classification after targeting us with a blazar

Not all black holes have jets, but when they do, the jets can point in any direction. If a jet shines on Earth, the object is called a blazar. – NASA/JPL-CALTECH


The initial classification as a radio galaxy of a massive cosmic structure has had to be modified due to the unique activity within its corerevealed in a new study.

PBC J2333.9-2343 is 4 million light-years across and has a blazar at its core.. A blazar is an active galactic nucleus (AGN) with a relativistic jet (a jet traveling close to the speed of light) directed toward an observer.

Blazars are very high energy objects and are considered one of the most powerful phenomena in the universe. Research has revealed that at PBC J2333.9-2343, the jet drastically changed its direction at an angle of up to 90 degrees, going from being in the plane of the sky, perpendicular to our line of sight, to point directly at us.

A blazar jet is made of charged elementary particles such as electrons or protons that move at speeds close to the speed of light. These move in circles around a strong magnetic field, causing the emission of radiation across the entire electromagnetic spectrum. At PBC J2333.9-2343, the jet is believed to originate near the supermassive black hole at its center.

With the jet pointing in our direction, the emission is strongly enhanced and can easily exceed that from the rest of the galaxy. This, in turn, generates stronger high-intensity flares than those from other radio galaxies, thus changing its categorization.

The orientation of the jets towards us determines how a galaxy is classified. When two jets point towards the plane of the sky, they are classified as a radio galaxy, but if one of the jets points towards us, then the AGN of the galaxy is known as a blazar. With jets in the plane of the sky and one directed towards us, PBC J2333.9-2343 has been reclassified as a radio galaxy with a blazar at its center, reports the Royal Astronomical Society in a statement.

Changes in the direction of the jets have been described in the past, for example with X-shaped radio galaxies. This is the first time such a phenomenon has been observed that does not suggest the presence of two different phases of jet activity. from its observed morphology at radio frequencies: the change in direction appears to have taken place in the same nuclear burst that originated from the AGN.

The work is published in Monthly Notices of the Royal Astronomical Society.

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