New research on giant radio galaxies defies conventional wisdom

Conventional wisdom tells us that large objects appear smaller as they get farther from us, but this fundamental law of classical physics is reversed when we observe the distant universe.

Astrophysicists at the University of Kent simulated the development of the biggest objects in the universe to help explain how galaxies and other cosmic bodies were formed. By looking at the distant universe, it is possible to observe it in a past state, when it was still at a formative stage. At that time, galaxies were growing and supermassive black holes were violently expelling enormous amounts of gas and energy. This matter accumulated into pairs of reservoirs, which formed the biggest objects in the universe, so-called giant radio galaxies. These giant radio galaxies stretch across a large part of the Universe. Even moving at the speed of light, it would take several million years to cross one.

Professor Michael D. Smith of the Centre for Astrophysics and Planetary Science, and student Justin Donohoe collaborated on the research. They expected to find that as they simulated objects farther into the distant universe, they would appear smaller, but in fact they found the opposite.

Professor Smith said: 'When we look far into the distant universe, we are observing objects way in the past - when they were young. We expected to find that these distant giants would appear as a comparatively small pair of vague lobes. To our surprise, we found that these giants still appear enormous even though they are so far away.'

Radio galaxies have long been known to be powered by twin jets which inflate their lobes and create giant cavities. The team performed simulations using the Forge supercomputer, generating three-dimensional hydrodynamics that recreated the effects of these jets. They then compared the resulting images to observations of the distant galaxies. Differences were assessed using a new classification index, the Limb Brightening Index (LB Index), which measures changes to the orientation and size of the objects.

Professor Smith said: 'We already know that once you are far enough away, the Universe acts like a magnifying glass and objects start to increase in size in the sky. Because of the distance, the objects we observed are extremely faint, which means we can only see the brightest parts of them, the hot spots. These hot spots occur at the outer edges of the radio galaxy and so they appear to be larger than ever, confounding our initial expectations.'

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The full research, The Morphological Classification of distant radio galaxies explored with three-dimensional simulations, has been published in the Monthly Notices of the Royal Astronomical Society.

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Notes to Editors

The University of Kent is a leading UK university producing world-class research, rated internationally excellent and leading the way in many fields of study. Our 20,000 students are based at campuses and centres in Canterbury, Medway, Athens, Brussels, Paris, Rome and Tonbridge.

With 97% of our research judged to be of international quality in the most recent Research Assessment Framework (REF2014), our students study with some of the most influential thinkers in the world. Universities UK recently named research from the University as one of the UK's 100 Best Breakthroughs of the last century for its significant impact on people's everyday lives.

We are renowned for our inspirational teaching. Awarded a gold rating, the highest, in the UK Government's Teaching Excellence Framework (TEF), we were presented with the Outstanding Support for Students award at the 2018 Times Higher Education (THE) Awards for the second year running.

Our graduates are equipped for a successful future allowing them to compete effectively in the global job market. More than 95% of graduates find a job or study opportunity within six months.

Known as the 'UK's European university', our international outlook is a major focus and we believe in our students developing a global perspective. Many of our courses provide opportunities to study or work abroad; we have partnerships with more than 400 universities worldwide and are the only UK university to have postgraduate centres in Athens, Brussels, Paris and Rome.

The University is a truly international community with over 40% of our academics coming from outside the UK and our students representing over 150 nationalities.

We are a major economic force in south east England, supporting innovation and enterprise. We are worth £0.9 billion to the economy of the south east and support more than 9,400 jobs in the region.

In March 2018, the Government and Health Education England (HEE) announced that the joint bid by the University of Kent and Canterbury Christ Church University for funded places to establish a medical school has been successful. The first intake of undergraduates to the Kent and Medway Medical School will be in September 2020.

We are proud to be part of Canterbury, Medway and the county of Kent and, through collaboration with partners, work to ensure our global ambitions have a positive impact on the region's academic, cultural, social and economic landscape.



This story has been published on: 2019-10-25. To contact the author, please use the contact details within the article.



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