LISA Ground Segment

This programme of work supports the UK leadership positions in the ground segment for LISA - the LISA Data Processing Group (LDPG) and the LISA Science Group (LSG) - as well as contributions to specific high-priority deliverables across the ground segment activities. This ground segment project will enable essential development activities that will ensure a high profile return for the UK - capitalising on the substantial hardware commitments to LISA - and with a profound impact on the wider scientific community.

This project involves four UK institutions, and focuses on:
1. Developments for the generation of TDI observables and their interface with instrument performance/monitoring and GW search pipelines;
2. Development and implementation of global end-to-end data processing pipelines;
3. Development and implementation of pipelines for the identification of extreme mass-ratio inspirals overlapping the "forest" of galactic double white dwarfs;
4. Development and implementation of data analysis tools with an emphasis on massive black hole binaries and noise characterisation;
5. Coordination of activities for assessment of requirements on waveform modelling and implementation of efficient waveform generations for data processing;
6. Coordination of activities for requirements on science analyses focused on the astrophysics of compact binaries and multi-messenger astronomy and development of prototype pipelines to meet these objectives.

In 2017 the Laser Interferometer Space Antenna (LISA) was selected by the European Space Agency as the third large-class mission to be developed under the Cosmic Vision programme. LISA comprises three spacecraft flying in a triangular formation maintaining a distance of 2.5 million kilometres between each spacecraft. LISA will be the first space-based gravitational wave observatory and will aim to detect low-frequency, millihertz gravitational-waves for the first time. Detecting these gravitational waves will allow us to study the properties of merging compact objects - including white dwarfs, neutron stars and black holes - throughout the Universe. The unprecedented sensitivity and frequency coverage of LISA will provide access to a large, and hitherto unexplored, population of compact objects; the smallest and lightest will be less massive than the Sun, whilst the largest will dwarf even the supermassive black hole in the centre of our own Milky Way galaxy.

This project focuses on the UK contribution to the ground-segment of the LISA mission. LISA poses many new and unique data processing challenges that need to be addressed for the effective delivery of the broad range of science stemming from the mission. Existing and developing expertise from ground-based gravitational-wave detection with LIGO and Virgo will inform some of these capabilities. However, unique to space-based gravitational wave detection, the multiple lasers on widely separated spacecraft will contain noise much larger than the gravitational wave signals that LISA seeks to detect; cancelling this laser noise will require new developments in a technique called time-delay interferometry. In addition, the LISA data set will contain millions of overlapping sources that are present in the data from the start to the end of the mission. Extracting details of all of these individual sources will require an all-new global approach to the data processing, and the development of the necessary data processing tools must be done in parallel with the instrument design. There are also challenges in the modelling of the compact object sources which must be addressed to enable the astrophysical and multi-messenger observations that are critical to the full success of the mission.

We have established our position as one of only 4 UK Universities to hold leadership positions within the LISA Consortium. We have contributed significantly to the LISA Science Group's "Data Analysis Tools" working package to collaboratively develop a toolkit to assess whether proposed design configurations will meet LISA's key science requirements.