Вадим Дудченко
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Centaurus A (NGC 5128) is a giant elliptical galaxy 12 million light-years away in the constellation of Centaurus. In its center lies an actively feeding black hole with a mass of 55 million solar masses. As the black hole feeds on in-falling gas, it ejects material at near light-speed, causing ‘radio bubbles’ to grow over hundreds of millions of years. Now, astronomers using the Murchison Widefield Array (MWA) telescope have produced the most comprehensive image of radio emission from these bubbles.

This MWA image shows Centaurus A at radio wavelengths, revealing vast lobes of plasma that reach far beyond the visible galaxy, which occupies only a small patch at the center of the image. The dots in the background are not stars, but radio galaxies much like Centaurus A, at far greater distances. Image credit: Ben McKinley, ICRAR & Curtin University / Connor Matherne, Louisiana State University.

“The MWA image reveals spectacular new details of the radio emission from Centaurus A,” said Dr. Benjamin McKinley, an astronomer with the Curtin University node of the International Centre for Radio Astronomy Research (ICRAR).

“These radio waves come from material being sucked into the supermassive black hole in the middle of the galaxy.”

“It forms a disk around the black hole, and as the matter gets ripped apart going close to the black hole, powerful jets form on either side of the disk, ejecting most of the material back out into space, to distances of probably more than a million light years.”

“Previous radio observations could not handle the extreme brightness of the jets and details of the larger area surrounding the galaxy were distorted, but our new image overcomes these limitations.”

“We can learn a lot from Centaurus A in particular, just because it is so close and we can see it in such detail. Not just at radio wavelengths, but at all other wavelengths of light as well,” he said.

“In this research we’ve been able to combine the radio observations with optical and x-ray data, to help us better understand the physics of these supermassive black holes.”

The study corroborated a novel theory known as Chaotic Cold Accretion (CCA), which is emerging in different fields.

“In this model, clouds of cold gas condense in the galactic halo and rain down onto the central regions, feeding the supermassive black hole,” said Dr. Massimo Gaspari, an astrophysicist with Italy’s National Institute for Astrophysics.

“Triggered by this rain, the black hole vigorously reacts by launching energy back via radio jets that inflate the spectacular lobes we see in the MWA image.”

“This study is one of the first to probe in such detail the multiphase CCA ‘weather’ over the full range of scales.”

Centaurus A appears brighter in the center where it is more active and there is a lot of energy.

“Then it’s fainter as you go out because the energy’s been lost and things have settled down,” Dr. Gaspari said.

“But there are interesting features where charged particles have re-accelerated and are interacting with strong magnetic fields.”

The findings were published this week in the journal Nature Astronomy.


B. McKinley et al. Multi-scale feedback and feeding in the closest radio galaxy Centaurus A. Nat Astron, published online December 22, 2021; doi: 10.1038/s41550-021-01553-3


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