Astronomers discover 9 new dwarf galaxies, the largest single find ever

10 Mar 2015

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The dwarf galaxy NGC 1232 captured by NASA's Chandra X-ray Observatory. Image via X-ray: NASA/CXC/Huntingdon Institute for X-ray Astronomy/G. Garmire; Optical: ESO/VLT

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As part of their efforts to better understand dark matter, astronomers from the University of Cambridge have actually discovered nine new dwarf galaxies orbiting the Milky Way, the largest single discovery ever.

The team that make up the Dark Energy Survey, who recently captured an incredible image of Comet Lovejoy, say that this discovery is also important because it marks the first time that dwarf galaxies have been discovered in almost a decade, the last of which came in 2005 and 2006 which was seen above Earth’s northern hemisphere.

According to Phys.org, a paper on their discovery will be presented as part of a joint project with their US counterparts in the Department of Energy's Fermi National Accelerator Laboratory where they are to show that each of these orbiting galaxies contains approximately 100 stars which makes them nearly 1bn-times fainter than our own Milky Way.

According to their findings, not all of the nine discoveries can be categorically defined as dwarf galaxies, rather, three can be confirmed as being dwarf galaxies while the rest can be either dwarf galaxies or globular clusters, the latter of which differs from dwarf clusters because it is not fused with dark matter.

Dwarf-galaxies

The Magellanic Clouds and the stream of neutral hydrogen. The insets show the image of the largest satellite discovered (Eridanus 2) as well as the smallest one (Indus 1). The insets are 13×13 arcminutes on the sky for Eridanus 2 and 6.5×6.5 arcminutes for Indus 1. Image via V Belokurov, S Koposov (IoA, Cambridge)

The closest of these objects is a mere 95,000 light years away, while the furthest is as far away as 1m light years.

By examining dwarf galaxies, the team from the University of Cambridge say that they will hopefully find more answers to the ever-elusive scientific understanding of what dark matter actually is, given that 99pc of dwarf galaxies are comprised of dark matter, while a quarter of the entire universe is believed to be comprised of it.

"Dwarf satellites are the final frontier for testing our theories of dark matter," said Dr Vasily Belokurov of the Cambridge team and one of the study's co-authors. "We need to find them to determine whether our cosmological picture makes sense. Finding such a large group of satellites near the Magellanic Clouds was surprising, though, as earlier surveys of the southern sky found very little, so we were not expecting to stumble on such treasure."

Colm Gorey is a journalist with Siliconrepublic.com

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