Astrophysics at the University of Birmingham

Lead Research Organisation: University of Birmingham
Department Name: School of Physics and Astronomy

Abstract

Most of our knowledge about the Universe at large has been derived from what scientists refer to as "electromagnetic radiation" - ranging from radio waves through infrared radiation and light, to X-rays and gamma rays. This has changed dramatically on September 14, 2015 when we directly detected for the first time ripples in space-time known as gravitational waves. The observational of the first gravitational-wave signal (GW150914) generated by the collision of two black holes has opened a new chapter in astronomy. We have discovered binary black holes, and learnt that every 15 minutes somewhere in the Universe two heavy stellar-mass black holes collide. In fact, since September 2015 we have observed five more collisions of this kind. On August 17, 2017 we observed GW170817, the first merger of a binary neutron star. Electro-magnetic radiation generated in the aftermath of the collision of the two neutron stars was then detected across the entire electromagnetic spectrum, from gamma-rays to radio waves, in possibly the most intense observational campaign of a single object in the history of astronomy. This first multi-messenger observation has demonstrated that double neutron star mergers are the engine powering at least some short-hard gamma ray bursts, and an important site for production of heavy elements, such as gold, in the Universe. The Birmingham group has played a key role in the development of the gravitational-wave instruments (Advanced LIGO) that enabled these discoveries, the analysis of the data, the characterisation of the properties of the sources, and the follow-up observational campaign of GW170817. In the coming years we expect to be able to observe a gravitational-wave signal every week, or possibly every day. We are preparing to use these signals from merging black holes and neutron stars to learn more about the evolution of these objects, stars, matter in extreme conditions, and to test our understanding of gravity itself. We are also developing the advanced technology which will be required to make future improvements to gravitational-wave observatories, so that more and much weaker signals can be observed and studied.

The capabilities of more conventional instruments to probe the distant Universe, and the capacity of large computers to simulate the influence of massive black holes at the centre of galaxies, continue to improve. We are bringing these developments together to advance our understanding of how structure in the universe - massive black holes, galaxies and clusters - form and evolve through cosmic time. A hot topic in astrophysics is the effort to understand the mysterious "dark energy" which powers the accelerating expansion of the Universe. We plan to use clusters of galaxies as probes of the structure and expansion history of the Universe on the largest scales, to advance our understanding of the nature of dark energy

Planned Impact

In terms of academic impact, the immediate beneficiaries include the UK (and international) astronomy and physics community, extending far beyond the applicant group. In the longer term, this research will provide new insights into the formation and evolution of massive black holes, galaxies and clusters, underpin reliable measurements of the mysterious component of our Universe that we call "dark energy", using clusters of galaxies. Research in gravitational-wave astronomy is expected to continue to transform our understanding of the Universe, including information on the properties of neutron stars and black holes, and the behaviour of gravity in extreme conditions; in the long-term it will offer a new window on the very early Universe, when it is was a fraction of a second old. This will benefit the widest astronomy/astrophysics community, internationally.

With regard to societal impact, cosmology, astrophysics and black holes, are exciting areas and reliably excellent topics for public outreach. We have directly experienced the broad high-impact generated by the direct detection of gravitational waves and the first multi-messenger observation of a double neutron star coalescence. New activities have been flourishing and we expect this to continue and increase in the future. This progress should also help revitalise public interest in science as a whole at a time when economic pressure could potentially shrink investment in science in general. An improved understanding of cosmology, clusters of galaxies as the largest structures in the cosmos, massive black holes at the centre of galaxies and the most violent collisions in the universe involving black holes and neutron stars, catch the public imagination, and produce demand for creative work. Our public engagements activities have already generated new online media for education and outreach, such as interactive computer games. They have attracted considerable attention and we have been developing these games for tablets and other platforms, which are reaching an even wider audience.

Work that we have carried out in the experimental area has already provided direct benefit to UK industry. Work that we have carried out for the construction of sensors and electronics for Advanced LIGO has already benefited local SMEs with contacts for about £1M. We are developing new quantum technologies and inertial sensors that have the potential of a variety of industrial applications for quantum systems, new gravity-gradient sensors and integrated system models for navigation systems. We plan to carry out a dedicated programme of knowledge transfer and industrialisation together with the Birmingham Quantum Hub and NPL. Our data analysis and statistics work is already finding applications outside our astronomy research in climate studies, and we plan to further develop this aspect of our activities to lead to direct industrial applications and wide societal impact.

Of course, the training which post-doctoral research assistants and PhD students receive within our grant-funded programme is also of much wider benefit to the academic and non-academic communities. For example many of our students and post-doctoral researchers have secured high-profile jobs in the high-tech and data-intensive sectors.

Publications

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