Murchison Widefield Array (MWA): Radio galaxy discovery near Earth spurs more questions

A radio galaxy is a galaxy which is associated with jets of emission which show up in radio wavelengths. 

ICRAR Astronomers have worked out that these jets come from super massive black holes at the centres of these galaxies. 

The region around the black hole is also visible in the radio, and this shows up as a bright 'core' in between the wider plumes. 

Credit: Dr Natasha Hurley-Walker

Western Australia astronomers have discovered a radio galaxy near Earth by accident.

The previously unknown radio galaxy is considered quite close to Earth, and was discovered late last year.

ICRAR astronomer Dr Natasha Hurley-Walker spotted the galaxy while in a team meeting last year looking at a digital image captured by the Murchison Widefield Array (MWA).

"I just saw this thing out of the corner of my eye and thought, that doesn't look right and it turns out it is one of these radio galaxies and it is very, very faint and it is very nearby," she says.

But while astronomers consider the galaxy quite close, it is redshift 0.0178 from earth and would take 248 million light years to get there.

Dr Hurley-Walker says the radio galaxy, named NGC1434 after the galaxy it is in, is very large, which may explain why astronomers had not spotted it in the past.

It is not dissimilar to earth in that it has star formation going on, and it has what is called a dust blain, which suggests it has not been agitated by galaxies colliding (mergers).

"The interesting thing about the object I found is that it's being hosted by a spiral galaxy, like our own," she says.

"This is a very rare occurrence—this is only the fifth of this type to be discovered, and by far the faintest."

Because it is quite near earth, it means the galaxy is quite old, possibly forming within a billion years after the big bang.

Dr Hurley-Walker says the discovery is also intriguing because at some point in its history the central black hole switched off but the radio jets have persisted.

Jets are narrow beams of matter spat out at high speed from near a black hole.

"That is kind of unusual because normally when we see these things, they are usually still on, have been for quite some time and that tells us the jets have persisted for a very long time.

"[This] is kind of interesting because it tells us that the electrons out there must have been very hot originally so there could still be radiation now," she says.

She does not know why the black hole switched off.

But to unlock the reasons and to find out more, she says researchers will need to observe the galaxy's central core with a high-resolution instrument with a very narrow field of view.

Murchison Widefield Array: Square Kilometre Array precursor debuts

Credit: mwatelescope.org

Solar storms, space junk and the formation of the Universe are about to be seen in an entirely new way with the start of operations today by the $51 million Murchison Widefield Array (MWA) radio telescope.

The first of three international precursors to the $2 billion Square Kilometre Array (SKA) telescope, the MWA is located in a remote pocket of outback Western Australia.

It is the result of an international project led by Curtin University and was officially turned on this morning by Australia's Science and Research Minister, Senator Kim Carr.

Using leading edge technology, the MWA will become an eye on the sky, acting as an early warning system that will potentially help to save billions of dollars as it steps up observations of the Sun to detect and monitor massive solar storms.

It will also investigate a unique concept which will see stray FM radio signals used to track dangerous space debris.

The MWA will also give scientists an unprecedented view into the first billion years of the Universe, enabling them to look far into the past by studying radio waves that are more than 13 billion years old.

This major field of study has the potential to revolutionise the field of astrophysics.

Steven Tingay

"This collaboration between some of astronomy's greatest minds has resulted in the creation of a groundbreaking facility," Director of the MWA and Professor of Radio Astronomy at Curtin University, Steven Tingay said.

"Right now we are standing at the frontier of astronomical science. Each of these programs has the potential to change our understanding about the Universe."

The development and commissioning of the MWA, the most powerful low frequency radio telescope in the Southern Hemisphere, is the outcome of nearly nine years' work by an international consortium of 13 institutions across four countries (Australia, USA, India and New Zealand).

The detailed observations will be used by scientists to hunt for explosive and variable objects in the Milky Way such as black holes and exploding stars, as well as to create the most comprehensive survey of the Southern Hemisphere sky at low radio frequencies.

From today, regular data will be captured through the entirely static telescope which spans a three kilometre area at the CSIRO's Murchison Radio-astronomy Observatory, future home to the SKA.

The data will be processed 800 kilometres away at the $80 million Pawsey High Performance Computing Centre for SKA Science, in Perth, carried there on a link provided by the NBN and enabled by AARNet. The MWA will be the Pawsey Centre's first large-scale customer.

Nine major research programs were announced at the launch, with more than 700 scientists across four continents awaiting the information the telescope has now begun to capture.

"Given the quality of the data obtained during the commissioning process and the vast areas of study that will be investigated, we are expecting to see preliminary results in as little as three months' time," Professor Tingay said.

"This is an exciting prospect for anyone who's ever looked up at the sky and wondered how the Universe came to be.

"The MWA has and will continue to lift the bar even higher for the SKA."

Peter Hall

Under Professor Tingay and fellow colleague Professor Peter Hall's guidance, Curtin University has been awarded a $5 million grant by the Australian Government to participate in the SKA pre-construction program over the next three years, with the MWA's unique insight being used to develop a low frequency radio telescope that is expected to be 50 times more sensitive.

The MWA project recognises the Wadjarri Yamatji people as the traditional owners of the site on which the MWA is built and thanks the Wadjarri Yamatji people for their support, as well as that of Astronomy Australia Limited.
Australia.