Spanish astronomers uncover new details about 'Einstein Ring' galaxy: Distance, shape and matter

LEGENDARY scientist Albert Einstein's theory of relativity predicted 'gravitational lensing', where spacetime is distorted by a mass that bends the path of light flow so that it does not move in a linear direction, creating what can look like a fiery ring when observed at the correct angle – and astronomers have now managed to examine one of these close up, and even measure how far it is from Planet Earth.

Cartagena Polytechnic (UPTC), near the coast in the south-eastern region of Murcia, released details of the ground-breaking research by an international astrophysics team led by its own Professor Anastasio Díaz, explaining how Hubble footage (shown above) had enabled them to locate the galaxy whose existence the historical genius predicted in the pre-War years.

It is 9.4 billion light years from Earth and, as seen on the space telescope, is four-dimensional, and actually a spiral rather than a circle.

Known universally as an 'Einstein Ring' – and also as an 'Einstein-Chwolson Ring' or simply 'Chwolson Ring', after fellow physicist Orest Khvolson inspired the more widely-recognised household name in a 1924 article describing a 'halo effect' of gravitation – this phenomenon was first captured on film by the European Space Agency (ESA) in December, but not in as great a detail as it has now.

The multi-national astronomer team led by Professor Díaz had to develop a gravitational lens model capable of examining the physical properties of the 'Einstein Ring', and which enabled them to view the galaxy amplified to 'factor 20' – the equivalent of seeing it through a 48-metre space telescope.

And no space telescope in current existence or development is that big.

The largest and most complete 'Einstein Ring' discovered to date, the galaxy observed is situated in a constellation near the southern hemisphere of the planet Fornax.

Light distortion, from a straight line into an apparent curve, is achieved naturally through the force of gravity generated by a cluster of other galaxies aligned with the one being studied, Professor Díaz explains.

It shows up on the newly-developed gravitational lens in quadruplicate, showing it to be a spiral rather than a 'halo', as found by observing it on multiple wavelengths.

Data from the FORS instrument, part of the Very Large Telescope (VLT) at the European Austral Observatory in Chile, enabled Professor Díaz – who has been studying this galaxy for many years – and his crew to work out the approximate 9.4-billion-light-year distance by applying the formula z = 1.47 to the 'movement to red' of the glow.

This 'movement to red' was ascertained 'very accurately' thanks to the detection of molecular gas, which new stars are born from, says fellow team member Nikolaus Sulzenauer of Germany's Max Planck Radioastronomy Institute.

Effectively, it means the light from the galaxy had travelled 9.4 billion years before it became visible through the Hubble space telescope.

Albert Einstein never expected it to be visible at all, in fact.

Following his investigations after reading Khvolson's paper 12 years earlier, Einstein wrote in his 1936 paper, published on page 506 of Science magazine, volume 84: “Of course, there is no hope of observing this phenomenon directly. First, we shall scarcely ever approach closely enough to such a central line. Second, the angle β [the 'Einstein Radius', now stated as θ¹] will defy the resolving power of our instruments.”

Spain has a long history of space research and developing space technology, is home to key satellites and observatories and played a major technical rôle in the moon landing, and other than Sulzenauer from the Max Planck Institute, all investigators in the 'Einstein Ring' gravitational lens development were based in Spain.

Along with Professor Díaz were H. Dannerbauer, S. Iglesias-Groth and R. Rebolo, all from the Canary Islands Astrophysics Institute, which is in San Cristóbal de la Laguna, Tenerife.

The results of their study have been published in The Astrophysical Journal.