SOLVE magazine Issue 02 2021 | Page 16

Dr Laura Nuttall
In 2020 Dr Laura Nuttall was awarded a Future Leaders Fellowship by UK Research and Innovation . The fellowship is to help researchers and innovators become world leaders in their field .
The fellowship will enable Dr Nuttall to further her investigations into different areas of gravitational-wave astronomy . One of the aspects Dr Nuttall will investigate is how changing LIGO sensitivity affects the ability to accurately measure the properties of gravitational-wave signals . She will also develop techniques to overcome periods of poor LIGO sensitivity .
“ We want to ensure that key parameters of the gravitational-wave signal , such as the sky location , masses and spins of the source , are unbiased ,” she says . “ This is critical to allow us to point electromagnetic telescopes to the correct sky location , understand the way in which the original binary system formed and measure the equation of state of neutron stars accurately .”
1.3 billion light years – the time it has taken for gravitational waves from two colliding black holes to be detected on Earth
Size of a gravitational wave when it reaches Earth – 1,000 times smaller than the nucleus of an atom
Anticipating a busy , stressful period ahead with the resumption of observations , she decided to go camping for a few days . As she walked back into signal range , her mobile phone lit up , and every message was the same . ‘ Get back . Now . This is happening .’
She needed no further urging : “ This was the promise of the theory that would revolutionise astronomy . And I was part of it .”
The first signal occurred on 14 September and Laura , who continues her research today through the University of Portsmouth ’ s Institute of Cosmology and Gravitation , recalls how that historic moment was initially dulled by concerns it was not real .
“ First we thought someone was playing with us , then we thought it might be false signals to test the new system and I remember my boss wondering whether anyone really would mess around like this just as we were resuming the LIGO program . It took a few days to eliminate all of these possibilities and confirm the signal was real , by which time we had all calmed down and it became very surreal .
“ There were people in the group who had been working towards this moment for 30 and 40 years , and of course it all started with Albert Einstein ’ s general theory of relativity in which he predicted there had to be gravitational waves of cosmic origin . It took a century before we had the technology to detect them … and this was that moment .”
LIGO scientists determined that the waves detected on that day were generated by two massive black holes , known as a binary black hole system , colliding about 1.3 billion years ago – the gravitational waves taking that long to reach us even at the speed of light .
The detection technology has continued to advance and the gravitational waves detected by LIGO ( and a sister observatory , Virgo , in Italy ) have carried new information and insights into the formation of the universe and the nature of gravity . Physicists had previously modelled the merger of two black holes to produce a single , massive and spinning black hole , but only now can these cataclysmic events be actually observed .
“ We ’ re really starting to dig into the binary black hole population and lift constraints from the science of astrophysics . It ’ s an exciting time ,” says Dr Nuttall , who is Senior Lecturer in Gravitational Waves at the University of Portsmouth .
“ One of the first realisations from that first detection was that black holes are much bigger than earlier electromagnetic observations had suggested , and that is already telling us something new about stellar evolution . We have also now observed , for the first time , a neutron star merger .”
Dr Nuttall says that a better understanding of neutron stars , formed – like black holes – when the core of a star collapses in on itself , could lead to a better understanding of the nuclear processes of
ISSUE 02 / 2021