How fast the Universe is expanding

A PhD student at the University of Western Australia has produced one of the most accurate measurements ever made of how fast the Universe is expanding.

Florian Beutler, a PhD candidate with the International Centre for Radio Astronomy Research (ICRAR) at the University in Perth, made the calculation by measuring 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.

As the Universe swells, it carries other galaxies away from ours. The Hubble constant links how fast galaxies are moving with how far they are from us.

Beutler’s work draws on data from a survey of more than 125,000 galaxies carried out with the UK Schmidt Telescope in eastern Australia.

Called the 6dF Galaxy Survey, this is the biggest survey to date of relatively nearby galaxies, covering almost half the sky.

Using a measurement of the clustering of the galaxies surveyed, plus other information derived from observations of the early Universe, Beutler has measured the Hubble constant with an uncertainly of less than 5 percent.

“The new measurement agrees well with previous ones, and provides a strong check on previous work,” stated Professor Matthew Colless, Director of the Australian Astronomical Observatory and one of the study’s co-authors.

The study was published in the Monthly Notices of the Royal Astronomical Society.