The 6df Galaxy Survey data

So, how big is the universe? Well, it’s hard to know because it keeps expanding. But, thanks to new research, scientists may be able to better determine how fast the expansion occurs.

Florian Beutler, a doctoral candidate at The International Centre for Radio Astronomy Research (ICRAR) at University of Western Australia in Perth has figured out how quickly the universe is expanding by refining the Hubble constant.

“The Hubble constant is a key number in astronomy because it’s used to calculate the size and age of the universe,” Beutler said in a news release about the new research.

As it grows, the universe carries galaxies away from our own Milky Way. The Hubble constant links how fast galaxies are moving with their distance from the Earth.

Using light from distant galaxies, scientists are able to calculate the speed and direction that the galaxies are moving. But their distance from the Earth has always proven trickier to ascertain.

Prior to Beutler’s new use of the Hubble constant, astronomers would observe the brightness of an object within a galaxy and then calculate how far away it was.

This process, although well-established, was prone to errors.

Beutler’s new approach used data from a survey of more than 125,000 galaxies collected by the K Schmidt Telescope in eastern Australia.

This survey covers almost half the sky, including a range of nearby galaxies.

Since galaxies are clustered throughout the universe, Beutler used a measurement of the clustering plus information from other universe surveys to refine the Hubble constant to an uncertainty of less than 5 percent.

“This way of determining the Hubble constant is as direct and precise as other methods, and provides an independent verification of them,” says professor Matthew Colless, director of the Australian Astronomical Observatory and one of the study’s co-authors.

“The new measurement agrees well with previous ones, and provides a strong check on previous work.”

Incorporating data from other surveys as well as future research will help astronomers refine the Hubble constant even further.

This study appears in the Monthly Notices of the Royal Astronomical Society Journal.

Photo: The 6df Galaxy Survey data, each dot is a galaxy and Earth is at the centre of the sphere.