Astronomers just mapped 1 million previously unknown galaxies and you can take a tour

Astronomers have mapped about a million as yet unknown galaxies beyond the Milky Way, in the most detailed study of the southern sky ever using radio waves.

The Rapid ASKAP Continuum Survey (or RACS) placed the Australian SKA Pathfinder (ASKAP) radio telescope from CSIRO on the international astronomical map.

While previous surveys have taken years to complete, ASKAP’s RACS survey was conducted in less than two weeks – shattering previous speed records. The data collected produced images that were five times more sensitive and twice as detailed as previous ones.

What is radio astronomy?

Modern astronomy is a multi-wavelength business. 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 visible and invisible light like x-rays, ultraviolet light, infrared light, and radio waves.

To understand the Universe, we need to observe the entire electromagnetic spectrum because 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 gas clouds to supermassive black holes.

Long wavelengths pass through clouds, dust, and the atmosphere with ease, but must be received with large antennas. Australia’s wide open spaces (albeit at relatively low altitudes) are the ideal place to build large radio telescopes.

We have some of the most spectacular views of the center of the Milky Way from our position in the southern hemisphere. Indigenous astronomers have enjoyed this benefit for millennia.

An exceptional 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 the University of Sydney’s Molonglo Sky Survey. Completed in 2006, this survey took nearly a decade to observe 25 percent of the entire sky and produce final data products.

Our team from CSIRO’s Astronomy and Space Sciences division broke 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 them into one map covering the entire area.

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

Take our virtual tour below (it works best on larger screens).

Astronomers working on the catalog have identified around three million galaxies – far more than the 260,000 galaxies identified in the Molonglo Sky Survey.

Why do we need to map the universe?

We know how important maps are on Earth. They provide crucial navigation aid and offer field information that is useful for land management.

Likewise, star charts provide astronomers with an important context for research and statistical power. They can tell us how some galaxies behave, such as whether they exist in groups of companions or if they drift into space on their own.

Being able to conduct an entire sky survey in less than two weeks opens up many research opportunities.

For example, little is known about how the radio sky evolves over time scales ranging from days to months. We can now regularly revisit each of the three million galaxies identified in the RACS catalog to monitor any differences.

In addition, some of the biggest unanswered questions in astronomy relate to how galaxies have become the elliptical, spiral, or irregular shapes we see. A popular theory suggests that large galaxies develop through the merger of several smaller ones.

But the details of this process are elusive and difficult to reconcile with simulations. Understanding the approximately 13 billion years of cosmic history of our Universe requires a telescope capable of seeing vast distances and accurately mapping anything it finds.

Centaur A galaxy captured in the RACS survey with an “intensity” represented by different colors. (CSIRO)

High tech puts new goals at your fingertips

CSIRO’s RACS survey is an incredible breakthrough made possible by tremendous advancements in space technology. The ASKAP radio telescope, which became fully operational in February last year, was designed for speed.

CSIRO engineers have developed innovative radio receivers called “phased array power supplies” and high speed digital signal processors especially for ASKAP. It is these technologies that provide ASKAP’s wide field of view and rapid survey capability.

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

In the meantime, the RACS survey catalog considerably improves our knowledge of the radio sky. It will continue to be a key resource for researchers around the world.

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

Aidan Hotan, ASKAP Senior Scientist, CSIRO.

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