We Just Found Two Mysterious Galaxies 62 Times Bigger Than Our Milky Way, Say Scientists
The two giant radio galaxies found with the MeerKAT telescope. In the background is the sky as seen … [+]
I. Heywood (Oxford/Rhodes/SARAO)
Astronomers using a huge radio telescope in South Africa have found two of the largest known single objects in the Universe.
About 22 times larger than our Milky Way, these “giant radio galaxies” were found in a tiny patch of the night sky.
That’s lead the authors of a new paper published today in the Monthly Notices of the Royal Astronomical Society to speculate whether there are many more of these “cosmic beasts” than previously thought.
“We found these giant radio galaxies in a region of sky which is only about four times the area of the full Moon,” said Dr Jacinta Delhaize, a Research Fellow at the University of Cape Town and lead author of the work.
That’s about 1º. The probability of finding two giant radio galaxies (GRGs) in such a small area is rated at less than 0.0003 per cent. “This means that giant radio galaxies are probably far more common than we thought,” said Delhaize.
What is a giant radio galaxy?
It’s an enormous galaxy about 700 kilo-parsecs in size, or about 22 times the size of the Milky Way, and over 2.28 million light years in length.
Only 831 “giant radio galaxies” are thought to exist.
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Most are elliptical galaxies with massive black holes.
It’s reckoned that GRGs have existed for several hundred million years, long enough for their radio jets to grow to enormous sizes.
If that’s true, then many more GRGs should have been identified by now.
Centaurus A is a famous example of a relatively nearby radio galaxy. Inside the galaxy is a … [+]
ESO/WFI (Optical); MPIfR/ESO/APEX/A.Weiss et al. (Submillimetre); NASA/CXC/CfA/R.Kraft et al. (X-ray).
How big are these newly found ‘giant radio galaxies?’
MGTC J095959.63+024608.6 and MGTC J100016.84+015133.0 are much, much bigger than “regular” GRGs.
“These two galaxies are special because they are amongst the largest giants known, and in the top 10 per cent of all giant radio galaxies,” said Dr Matthew Prescott, a Research Fellow at the University of the Western Cape and co-author of the work. “They are more than two mega-parsecs across, which is around 6.5 million light years or about 62 times the size of the Milky Way. Yet they are fainter than others of the same size.”
How were these two giant radio galaxies found?
They were found in new radio maps of the sky created by the MeerKAT International Gigahertz Tiered Extragalactic Exploration (MIGHTEE) survey at South Africa’s MeerKAT radio telescope.
Radio astronomy is the study of celestial objects that give off radio waves to reveal otherwise hidden emissions, blasts and signals. It helps reveal the Universe as it really is rather than merely how it looks.
South Africa’s MeerKAT telescope.
South African Radio Astronomy Observatory (SARAO)
What is the MeerKAT telescope?
Radio telescopes are typically a myriad of dishes. Located in the Karoo region of South Africa, the new MeerKAT telescope is comprised of 64 radio dishes.
It’s the precursor to the Square Kilometre Array (SKA), a radio telescope that will cover both South Africa and Australia. When the SKA becomes operational in the mid-2020s, it’s hoped that its sensitivity will reveal many more radio galaxies—and revolutionise our understanding of how galaxies evolve.
Wishing you clear skies and wide eyes.