SA scientist helps unveil merging galaxies

19 September 2013 - 14:27 By Times LIVE
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Dr Mattia Vaccari. File photo
Dr Mattia Vaccari. File photo
Image: UWC

A University of the Western Cape researcher is part of a team that spotted the rare process of two galaxies merging into one.

In the constellation of Cetas, two galaxies smashed into each other and merged over 200 million years.

11 billion years later, scientists observed part of this process with the aid of the Herschel Space Observatory, according to a statement by the university.

Dr Mattia Vaccari, a postdoctoral researcher with the astrophysics group at the University of the Western Cape and one of the authors of the study that unveiled the newly formed galaxy in Nature, helped tweak the observatory's sensors.

Those detectors helped the observatory push through the stardust that HXMM01's merger kicked up and see the light born of that cosmological marriage.

The 11 billion year old heat signatures told the scientists a lot about the new galaxy, which is ten times the size of ours and about 11 billion lightyears away.

That data is giving scientists pause for thought, as it suggests that HXMM01 eventually grew into an elliptical galaxy, which were thought to be rare in the early universe.

The temperature of the galaxy's dust is also quite high at about -218C, which means that with the galaxy's gas stores HXMM01 churned out about 2 000 stars a year, more than a thousand times the number being produced by the Milky Way.

“The fact that it is forming stars at such a high rate is challenging our conceptions,” said Vaccari.

Dr Romeel Davé, who holds the national research chair in multi-wavelength cosmology at UWC, is also intrigued by the data.

“That fact that an object like HXMM01 led to an elliptical galaxy is also something that we can’t explain within our simulations, because most of the processes that we model for the formation of such a huge galaxy seem to take a longer than we can see in HXMM01,” said Davé.

While Herschel has run out of fuel, meaning that all further observations of the new galaxy will have to be done from land, the researchers will be able to tap into readings taken off MeerKAT, which will be incorporated in the international Square Kilometre Array.

“MeerKAT will allow us to observe the same areas of the sky as we did with Herschel,” said Vaccari, “in order to provide another vantage point – at a different wavelength and thus in a different colour of the spectrum – onto the process of star formation.”

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