We’ve mapped a million previously undiscovered galaxies beyond the Milky Way. Take the virtual tour here.



CSIRO, Author provided

Aidan Hotan, CSIRO

Astronomers have mapped about a million previously undiscovered galaxies beyond the Milky Way, in the most detailed survey of the southern sky ever carried out using radio waves.

The Rapid ASKAP Continuum Survey (or RACS) has placed the CSIRO’s Australian SKA Pathfinder radio telescope (ASKAP) firmly on the international astronomy map.

While past surveys have taken years to complete, ASKAP’s RACS survey was conducted in less than two weeks — smashing previous records for speed. Data gathered have produced images five times more sensitive and twice as detailed as previous ones.

What is radio astronomy?

Modern astronomy is a multi-wavelength enterprise. What do we mean by this?

Well, most objects in the universe (including humans) emit radiation over a broad spectrum, called the electromagnetic spectrum. This includes both visible and invisible light such as X-rays, ultraviolet light, infrared light and radio waves.

To understand the universe, we need to observe the entire electromagnetic spectrum as each wavelength carries different information.

Radio waves have the longest wavelength of all forms of light. They allow us to study some of the most extreme environments in the universe, from cold clouds of gas to supermassive black holes.

Long wavelengths pass through clouds, dust and the atmosphere with ease, but need to be received with large antennas. Australia’s wide open (but relatively low-altitude) spaces are the perfect place to build large radio telescopes.

We have some of the most spectacular views of the centre of the Milky Way from our position in the Southern Hemisphere. Indigenous astronomers have appreciated this benefit for millennia.




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A stellar breakthrough

Radio astronomy is a relatively new field of research, dating back to the 1930s.

The first detailed 30cm radio map of the southern sky — which includes everything a telescope can see from its location in the Southern Hemisphere — was Sydney University’s Molonglo Sky Survey. Completed in 2006, this survey took almost a decade to observe 25% of the entire sky and produce final data products.

Our team at CSIRO’s Astronomy and Space Science division has smashed this record by surveying 83% of the sky in just ten days.

With the RACS survey we produced 903 images, each requiring 15 minutes of exposure time. We then combined these into one map covering the entire area.

The resulting panorama of the radio sky will look surprisingly familiar to anyone who has looked up at the night sky themselves. In our photos, however, nearly all the bright points are entire galaxies, rather than individual stars.

Take our virtual tour below.

Astronomers working on the catalogue have identified about three million galaxies — considerably more than the 260,000 galaxies identified during the Molonglo Sky Survey.

Why do we need to map the universe?

We know how important maps are on Earth. They provide crucial navigational assistance and offer information about terrain which is useful for land management.

Similarly, maps of the sky provide astronomers with important context for research and statistical power. They can tell us how certain galaxies behave, such as whether they exist in clusters of companions or drift through space on their own.




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Being able to conduct an all-sky survey in less than two weeks opens numerous opportunities for research.

For example, little is known about how the radio sky changes over timescales of days to months. We can now regularly revisit each of the three million galaxies identified in the RACS catalogue to track any differences.

Also, some of the largest unanswered questions in astronomy relate to how galaxies became the elliptical, spiral, or irregular shapes we see. A popular theory suggests large galaxies grow via the merger of many smaller ones.

But the details of this process are elusive and difficult to reconcile with simulations. Understanding the 13 billion or so years of our universe’s cosmic history requires a telescope that can see across vast distances and accurately map everything it finds.

Image of the Centaurus A galaxy.
The giant Centaurus A galaxy was one elliptical galaxy captured in the RACS survey. Although more than ten million light years away, it’s one of the closest radio galaxies to Earth. You can see its ‘intensity’ represented by different colours.
CSIRO, Author provided

High technology putting new goals within reach

The CSIRO’s RACS survey is an amazing advance made possible by huge leaps in space tech. The ASKAP radio telescope, which became fully operational in February last year, was designed for speed.

CSIRO’s engineers developed innovative radio receivers called “phased array feeds” and high-speed digital signal processors specifically for ASKAP. It’s these technologies that provide ASKAP’s wide field of view and rapid surveying capability.

Over the next few years, ASKAP is expected to conduct even more sensitive surveys in different wavelength bands.

In the meantime, the RACS survey catalogue is greatly improving our knowledge of the radio sky. It’ll continue to be a key resource for researchers around the world.

Full resolution images can be downloaded from the ASKAP data archive.The Conversation

Aidan Hotan, ASKAP lead scientist, CSIRO

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Victoria just gave 2 billion litres of water back to Indigenous people. Here’s what that means for the rest of Australia



GLaWAC

Troy McDonald, Indigenous Knowledge and Erin O’Donnell, University of Melbourne

For the first time in Victoria’s history, the state government has handed back water to traditional owners, giving them rights to a river system they have managed sustainably for thousands of years.

The two billion litres of water returned to the Gunaikurnai Land and Waters Aboriginal Corporation (GLaWAC) this month means traditional owners can now determine how and where water is used for cultural, environmental or economic purposes.

The decision recognises that water rights are crucial for Indigenous people to restore customs, protect their culture, become economically independent and heal Country.

The hand-back to Gunaikurnai people is the crucial first step in a bigger, statewide process of recognising Indigenous people’s deep connection to water. It also serves as an example to the rest of Australia, where Indigenous rights to water are grossly inadequate.

Water from the river has
Gunaikurnai woman Alice Pepper on the banks of the Mitchell River. Water from the river has been handed back to traditional owners.
GLaWAC

Water’s rightful home

Gunaikurnai people hold native title over much of Gippsland, from the mountains to the sea.

The water hand-back comes ten years since this native title was secured, and since Gunaikurnai people entered into the state’s first Traditional Owner Settlement Agreement with the government. Under this agreement, GLaWAC is a joint manager, with Parks Victoria, of ten parks and reserves in Gippsland, including the Mitchell River National Park.

Victorian water minister Lisa Neville said the hand-back was a key milestone in her government’s 2016 Aboriginal Water Policy. That plan aims to:

  • recognise Aboriginal values and objectives of water
  • include Aboriginal values and traditional ecological knowledge in water planning
  • support Aboriginal access to water for economic development
  • build capacity to increase Aboriginal participation in water management.

GLaWAC engages closely with government agencies that control how water is shared and used and these partnerships are highly valued. But it is only through owning water that traditional owners can really control how water is used to care for Country and for people.

For the moment, the water will be staying in the river. Its use will be decided after discussions between GLaWAC and Gunaikurnai community members.

The Mitchell River
Indigenous poeple must own water to control how they care for Country.
GLaWAC

Barriers to water ownership

In 2016, the Victorian government committed A$5 million to a plan to increase Aboriginal access to water rights, including funding for traditional owners to develop feasibility plans to support water-based businesses.

There are significant barriers to reallocating water to Victoria’s traditional owners. Water is expensive to buy, hold and use. Annual fees and charges can easily run to tens of thousands of dollars a year in some locations.

Using water to care for Country supports well-being, the environment and other water uses, including tourism and recreation. But, unlike using water for irrigation, there may not be any direct economic return from a water hand-back. This means water recovery for traditional owners must include ways to cover fees and charges.




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Victoria’s water entitlement framework is also consumption-based – it is designed for water to be taken out of rivers, not left in. This can make it hard for traditional owners to leave water in the river for the benefit of the environment. So water entitlements and rules should be changed to reflect how traditional owners want to manage water.

Lastly, many traditional owners lack access to land where they can use the water. Or they may wish to use water in areas that, under natural conditions, would be watered when rivers flood, but which are now disconnected from the waterway. To help overcome this, traditional owners should be given access to Crown land, including joint management of parks. GLaWAC’s partnership agreements are a good example of how this might happen in future.

GLaWAC water team Uncle Lloyd Hood and Tim Paton.
GLaWAC water team Uncle Lloyd Hood and Tim Paton. Water rules should be changed to reflect how traditional owners manage water.
GLaWAC

Change is possible

While significant barriers to water access remain, this hand-back shows how real water outcomes for traditional owners can be achieved when there is political will and ministerial support.

The water is part of six billion litres on the Mitchell River identified as unallocated, meaning no-one yet has rights over it. The remaining four billion litres will be made available on the open market, for use by irrigators or other industries. It can be extracted only during the colder months from July 1 to October 31.

The extraction and use of the water by Gunaikurnai people will be linked to specific locations, and the licence is up for renewal every 15 years. GLaWAC will work with state agency Southern Rural Water to ensure that the licence conditions match the water plans of traditional owners.

This step is crucial. There have been many instances in other states where traditional owners have obtained water, but been unable to use it due to barriers on how it can be used, and annual fees and charges.

Mitchell River scene
Water extraction form the Mitchell River will be limited to colder months.
GLaWAC

Overcoming a history of injustice

Traditional owners across Australia never ceded their rights to water. Yet Aboriginal people own less than 1% of the nation’s water rights. Righting this wrong is the “unfinished business” of national water reform.

Even when political commitments are made, there has been little progress. For example, in 2018 the federal government committed A$40 million to acquire water rights for Aboriginal people in the Murray-Darling Basin, but no purchase of water rights has yet occurred.

This woeful and unjust situation is also reflected in Victoria. Before the Gunaikurnai hand-back, only a tiny handful of Aboriginal-owned organisations and one traditional owner, Taungurung, owned water rights in Victoria, and the volumes were small. In these cases, water recovery was not a formal hand-back from the state, and included a donation from a farmer.

Across Australia, Aboriginal people are watching the Victorian water reform process with great interest. The water returned to Gunaikurnai people builds momentum, and increases pressure on governments across Australia to take water justice seriously.




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The Conversation


Troy McDonald, Chairman of Gunaikurnai Land and Waters Aboriginal Corporation, Indigenous Knowledge and Erin O’Donnell, Early Career Academic Fellow, Centre for Resources, Energy and Environment Law, University of Melbourne

This article is republished from The Conversation under a Creative Commons license. Read the original article.