Multi-band, Multi-messenger Astrophysics with LIGO, LISA and GOTO

This fellowship investigates different areas of gravitational-wave astronomy, from gravitational-wave detection to observing an optical counterpart and interpreting the resulting astrophysical implications. This will be done using three facilities, LIGO (Laser Interferometer Gravitational-wave Observatory), LISA (Laser Interferometer Space Antenna) and GOTO (Gravitational-wave Optical Transient Observatory). LIGO and LISA are both gravitational-wave detectors. LIGO consists of two detectors in the USA. They are sensitive to gravitational waves from 10 Hz to the kHz region. LISA is a future space-based detector, due for launch in the 2030s. LISA is sensitive to gravitational waves from 0.1 to 100 mHz. GOTO on the other hand is an Earth-based optical telescope.

Gravitational waves are emitted whenever an asymmetric object accelerates, with the strongest sources of detectable gravitational waves being from the collision of neutron stars and black holes. Both are created at the end of a massive star's life. Gravitational-wave astronomy truly began in 2015 when LIGO observed the gravitational-wave signature of two stellar-mass black holes colliding for the first time. Since then a total of eleven gravitational-wave signals have been observed, ten from the merger of two black holes, and one from the coalescence of two neutron stars. This latter signal was particularly exciting, as prior to this observation it was just speculation that colliding neutron stars would produce an electromagnetic signal. Indeed, in 2017 this binary neutron star merger was not only observed in the gravitational-wave window, but also across the electromagnetic spectrum. Over the coming years the LIGO detectors will become more sensitive, seeing deeper into the Universe and detecting many more gravitational waves.

In this fellowship, we will investigate how the changing nature of LIGO sensitivity affects our ability to accurately measure the properties of gravitational-wave signals. We 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. 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.

For LISA, it is imperative that we explore how to maximise the astrophysical potential of the future mission. In this fellowship, we will investigate how the expected changing nature of the LISA sensitivity will limit our ability to separate overlapping gravitational-wave signals. We will investigate techniques to overcome times of poor sensitivity in mock LISA data to separate out gravitational-wave signals and extract their astrophysical properties. This work will increase our chances of identifying unexpected astrophysical signals, as well as those we expect on all scales, from the smallest stellar-mass black holes to the colliding supermassive black holes at the heart of galaxies.

Another aspect of this research is to follow-up gravitational wave events with the GOTO telescope. So far, only one gravitational-wave signal has an identified electromagnetic counterpart. With GOTO, we will build a catalogue of the different types of optical signals we expect from different gravitational-wave sources. This will allow us to gain an understanding of how the different optical signatures inform us of the underlying astrophysics. For example, we will begin to understand what type of object is created in the collision of two neutron stars. This information is not easy to deduce from the gravitational-wave signal alone. We will also investigate whether a binary black hole merger will produce an optical counterpart. The presence or absence of an optical signature will begin to indicate how these merging black holes initially formed.

There are two areas of impact in my future leaders fellowship. The first is to further our knowledge of the Universe through gravitational-wave astronomy. This work will not only benefit researchers in the UK, but the entire astronomy community around the world. My team and I are committed to attaining impact from our research, particularly through public engagement. We will follow the Institute of Cosmology and Gravitation's (ICG) established outreach and public engagement strategy to maximise impact. our second area of impact will be in the areas of public engagement through large events, with school children, citizen science and with young visually impaired people.

Engagement through Large Events: The ICG runs an annual event in the Portsmouth Dockyard called Stargazing Live. This year we had several hundred members of the public attend. My team and I will develop demonstrations of our research for the public and subsequent Stargazing Live events. These will include demonstrations of LIGO through a table-top interferometer, aspects of the LISA spacecraft and the science of GOTO. We will aim to create a new demonstration every year.

Engagement through school children: The ICG partners will three local schools to engage with the same school pupils throughout their school career (9-18). Through this programme my team and I will deliver workshops and other activities of our research to inspire and encourage students to study physics at a higher level. We will also provide work placement opportunities for A-level students from these and other local schools to conduct research in our team. This will be provided through the work placement program currently under development at the ICG.

Engagement through citizen science: One of the objectives in this proposal will be to build a project in the Zooniverse to engage the public with multi-messenger astronomy, called "GOTOZoo". Anyone with a computer will have the potential to interact and contribute to our research.

Engagement with young visually impaired people: The Tactile Universe is an award-winning public engagement project at Portsmouth. It's current focus is to engage young visually impaired people in schools, to open up current astrophysics research to this community, build science capital, and raise aspirations and attainment. In doing so, we can show them that astrophysics can be a possible route of study and future career. My team and I will collaborate with the Tactile Universe team at Portsmouth to extend the reach of this project in to gravitational-wave astronomy.

My other ambition for this fellowship will be to improve the mental health and wellbeing of postgraduate researchers (PGRs), initially at the University of Portsmouth, but over time the wider UK population. I will join the established team who coordinate the PGR Wellbeing Project, funded through the Office for Students Catalyst Fund and Research England. The focus of this project is the development of online mental health resources, supervisor training and mentoring circles for PGRs at Portsmouth. These resources will then be made available to other UK universities. This project has the potential to impact the entire UK PGR population. In particular, it will benefit those PGRs who are most vulnerable. This project will encourage a more diverse PGR population, resulting in the strengthening of UK research the level of highly skilled people entering the UK workforce.

A further goal of the PGR Wellbeing Project is the implementation of an institutional PGR Mental Health and Wellbeing Strategy. Whilst this project is still aimed at PGRs, it has the potential to positively impact the entire university. By training to staff and thoroughly signposting ways to access help in a crisis, people will look after their own wellbeing in addition to others. This strategy will change university culture, and benefit all those who work and study at Portsmouth.