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Astronomers see galaxies in ultra-high definition

By Pallab Ghosh

Science correspondent

image sourceR. Timmerman/LOFAR

image captionA supermassive black hole at the centre of a galaxy, seen faintly in the centre, shoots out jets of material across space

Astronomers have captured some of the most detailed images ever seen of galaxies in deep space.

They are in much higher definition than normal and reveal the inner workings of galaxies in unprecedented detail.

Many of the images could yield insights into the role of black holes in star and planet formation.

The researchers say that the pictures will transform our understanding of how galaxies evolve.

The images are of the radio waves emitted by the galaxies. Researchers often study the radio waves from astronomical objects rather than the visible light they give off because it enables them to see things that would otherwise be blocked by the Earth’s atmosphere or dust and gas in faraway galaxies.

Many regions of space that are dark to our eyes, actually burn brightly in the radio waves they give off. This allows astronomers to peer into star-forming regions or into the heart of galaxies.

What is new is that the team has dramatically improved the resolution of radio images by linking together more than 70,000 small antennae spread across nine European counties.

image sourceBBC News

image captionThe radio signals have been captured by 70,000 one-metre-high antennas across nine European countries

Combining radio signals from so many antennas is not a straight-forward process. The team has spent six years developing a completely new way of collecting the signal from each antenna, digitising it, transporting it to a to central processor, and then combining all the data into images that are not only of enormous scientific interest but also of great beauty.

The accomplishment is a technical tour de force and was led by Dr Leah Morabito from Durham University, UK.

“To work on the data for so long, and then to finally get such images and be able be the first person to see what it looks like is just incredible,” she told BBC News.

“I walked around with a huge smile on my face for the rest of the day, because I felt so proud that I was able to make these images and be able to see something nobody had ever seen before”.

The image at the top of the page was produced by a member of Dr Morabito’s team. It shows a galaxy that is barely visible, sitting in the middle of jets of material in orange, shooting out from either side, each one much larger than the galaxy itself.

The jets are caused by a supermassive black hole at the heart of the galaxy- an object with such strong gravity not even light can escape. It normally sucks in material – but the inward pull also creates forces around the black hole that result in material being spat out, far into space.

Such jets have been observed before – but astronomers have obtained new scientific information from the dark bands on the jet on the right, which have not been seen before. These, the astronomers believe, represent periods of relative inactivity by the black hole – when it spits out less material. The image therefore gives researchers an insight into the black hole’s “sleep cycle”.

image sourceN. Ramirez-Olivencia/LOFAR

The picture above shows two galaxies colliding. the bright spot on the one on the left is caused by exploding stars – creating what is effectively a galactic wind – blowing dust and gas away from it.

image sourceF. Sweijen/LOFA

The light from the galaxy shown directly above originated when the Universe was only 2.6 billion years old. Above and below it are jets of material thrown out by the black hole within. Normally such early galaxies can’t be studied in detail. But now, for the first time, the astronomers have seen the structure of one of them at radio frequencies – which provides critical scientific information about how the black hole is interacting with its surroundings.

The images are revealing that galaxies are much more than a collection of stars. They are dynamic sun- and planet-making factories, powered by black holes, according to Dr Neal Jackson, from the University of Manchester.

“Even seasoned astronomers go ‘wow!’ when they see these images,” he told me.

“It’s become very clear that, in order to understand galaxy evolution, we need to understand the black hole right at the very centre, because it appears to have a fairly fundamental influence on how galaxies evolve and that is what these images allow us to do,” says Dr Jackson.

“These high-resolution images allow us to zoom in to see what’s really going on when supermassive black holes launch these jets of material.”

image sourceL. K. Morabito/L.K. Williams

image captionThe picture on the left is of a galaxy observed in visible light. The middle image shows the same galaxy but seen at radio frequencies and on the right is the high-definition image.

Dr Morabito says that images like these are helping astronomers learn just how these processes, that created stars and planets – including our own Solar System – actually work.

“We are really beginning to understand how galaxies have evolved. And the black holes are a massive part of that because their jets can take away fuel for star formation. And as they push outwards, they can disrupt the galaxies. They can even trigger star formation or quench it and make it happen less,” she said.

The first set of results have led to the publication of nine scientific papers on the dynamics of black holes in galaxies. But this is just the start for the team. They plan to scan millions of galaxies over the next few years.

“And that’s really what we need to be able to understand, the whole complete picture of how black holes impact galaxy evolution,” says Dr Morabito,

“I think we’re definitely in for some surprises. Whenever you start doing something new in astronomy you always find out things that you never expected and that’s what I really look forward to.”

The international network of telescopes is known as the Low Frequency Array known as Lofar for short. Most of the antennas are located in Exloo in the Netherlands.

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