Saturday, 08 December 2012

Galaxy-scale jet resembles fighter plane afterburner

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jetstreamThe jet clearly showing the shock diamond-like shapes in the two million light year long structure. Image: Dr Leith Gofrey ICRAR & Dr Jim Lovell UTas.A NEW image of a galaxy-scale cosmic jet baring a striking resemblance to a fighter jet’s afterburner flow may provide astronomers with new insights into how galaxies form and grow.

The image shows a supersonic jet of material blasting over two million light years from the centre of a distant galaxy.

Dr Leith Godfrey from Curtin University’s node of the International Centre for Radio Astronomy (ICRAR) studied the jet and co-authored the research published in the Astrophysical Journal Letters.

According to Dr Godfrey these cosmic jets are produced when material falls onto a supermassive black hole at the centre of a galaxy, but many details beyond that remain unknown.

This new image of galaxy-scale jet PKS 0637-752 reveals regularly spaced areas that are brighter than the rest echoing the bright diamond shaped pattern of an afterburner flow known as ‘shock diamonds’.

Dr Godfrey says one intriguing possibility is that the two types of jets (plane afterburner and cosmic) produce their similar patterns in the same way.

“If the brighter patches are caused by the same process in astronomical jets as they are in earthly jet engines, then the distance between them can give us important information about the power of the jet and the density of the surrounding space,” he says.

“Massive jets like this one have been studied for decades, since the beginning of radio astronomy, but we still don’t understand exactly how they are produced or what they’re made of.”

Galaxy-scale jets like the one studied by Dr Godfrey are the largest objects in the Universe measuring 100 times larger than the milky way.

Dr Godfrey says understanding these jets is essential to understanding how galaxies form and grow.

“They are extremely powerful and are believed to be able to stop stars from forming in their parent galaxy, limiting how big the galaxies can grow and effecting how the Universe looks today.”

This new image, taken using the CSIRO managed Australia Telescope Compact Array in New South Wales, shows detail never seen by astronomers in the past, according to co-author and University of Tasmania’s Dr Jim Lovell.

“This particular jet emits a lot of X-rays, which is hard to explain with our current models,” he says.

“Our new find is a step forward in understanding how these giant objects emit so much X-Ray radiation, and indirectly, will help us understand how the jet came to be.”

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