Durban - Poets and lovers alike have saluted their beauty, but starry skies are more than just a backdrop to romantic evenings.
They provide valuable clues to the universe’s origins and age – and, possibly, what the next stage in its development will be.
Two academic researchers – both affiliated with the University of KwaZulu-Natal’s Astrophysics and Cosmology Research Unit – have made groundbreaking astronomical discoveries based on data collected by the Hubble Space Telescope, a joint venture by Nasa and the European Space Agency.
The university announced that Dr Mathilde Jauzac, a former astrophysics and cosmology postdoctoral researcher and an affiliate of the unit, had measured the mass of a merging galaxy cluster named MACSJ0416, to the highest precision yet.
This had allowed her team, which included PhD student Kenda Knowles, to determine the geometry and dynamics of this cosmic collision, about 4.5 billion light years away from Earth, said the university last week.
It added that the cluster was estimated to have formed 9.2 billion years after the Big Bang.
“The cluster was modelled to be over 650 000 light years across and its mass was found to be 160 trillion times the mass of the sun.”
And while this meant nothing to the inhabitants of Earth itself, explained Jauzac, the breakthrough would be instrumental in improving our knowledge and understanding of the universe.
“Earth and other planets are situated in the proximity of the sun,” she said.
“Then, the sun is part of our galaxy, called the Milky Way. The Milky Way is composed of billions of stars (suns). Finally, our galaxy is part of a cluster of galaxies, called the Local Cluster, composed of thousands of galaxies.
“Thus, we are talking about very, very different scales – except improving our understanding of how our universe evolves and is forming, it does not give us anything else. But that’s also what is beautiful with what we are doing (which is) just improving knowledge, and trying to answer the oldest questions humanity ever asked itself,” Jauzac said on Friday.
She explained that researchers were now able to understand how the galaxy cluster ended up looking the way it did.
“To make it simple, imagine that matter in the universe is like humans on Earth. Exceptions do exist, but in majority most humans do not like to live by themselves, so what’s going to happen is that they will go where other humans are – for example, most of them are moving to the big cities while fewer of them are staying in the countryside.”
She said galaxies were the same as people.
“If you consider a galaxy to be a human, and the galaxy cluster being the big city, then galaxies will be attracted by the gravitational force of the cluster – and thus they will ‘fall’ into the cluster.”
Jauzac “weighed” the galaxy cluster by measuring how it warped the space around it, distorting the apparent shapes of distant objects behind it, like the view through a bathroom window. This distortion, she said, was known as gravitational lensing.
“A really massive object (like a galaxy cluster) will wrap and distort … (It) magnifies the light emitted by background galaxies that travel through it. The cluster is thus acting as a lens – a cosmic (natural) telescope.”
She said thanks to this effect, scientists were able to look back into space and time and learn about the early universe.
Jauzac also led an international research study to analyse data collected by the Hubble Space Telescope’s Frontier Field initiative which began exploring the universe in October last year.
A lensing workshop was hosted by the Astrophysics and Cosmology Research Unit and funded by the National Research Foundation in January 2014 in order to analyse the first set of data from the Hubble initiative, and to introduce gravitational lensing to the South African science community.
“It was while working on one of the projects at the workshop that Knowles discovered a new multiply-imaged system, leading to her inclusion in the international collaboration.
“She assisted in the discovery and confirmation of other multiply-imaged systems which were used to provide a better estimate of the mass of MACSJ0416, thus allowing scientists to have a better understanding of the structure of the newly discovered galaxy,” said the university.
Daily News