The International LOFAR Two-metre Sky Survey (ILoTSS) will extend and build on the highly successful LoTSS survey to be the first wide-area, sensitive (30 μJy beam^-1), high resolution (0.3 arcsec) extragalactic radio survey. The science goals are extensive, and we highlight some here.

• This survey will robustly characterise the whole AGN population, including the emerging low-luminosity population, and resolve all jets on kpc scales, which is essential for understanding the AGN physics, their galaxy-scale feedback and for separating the AGN and star formation contributions.
• In the local Universe, the study of nearby galaxy halos will determine the role of cosmic ray transport in stellar and galactic feedback...
• ... while at higher z ILoTSS will characterise the AGN and star formation activity in more than a million quasars out to z ~ 6, and map the growth of the earliest black holes (z > 6).
• Due to its 0.3 arcsec resolution ILoTSS will be a gravitational lens finding machine, with >5000 new radio-loud lens systems expected, enabling unique tests of high-z galaxy populations and cosmology.
• The ILoTSS source counts will be used to independently constrain the cosmological parameters, and determine the radio source count dipole at high significance, which may have dramatic implications for the cosmological principle.

We are also proposing to complete LoTSS, for legacy value and to provide the first low-frequency high-resolution study of the Milky Way, probing the detailed physical structure of the ISM in addition to discovering new pulsars. Finally, ILoTSS will open up new discovery space in cosmic magnetism and the time-domain Universe, and provide new insights on exoplanet-induced emission, their periodicity and the space weather conditions for over 100 stellar systems.

The potential and full range of science cases for international baseline resolution data is evolving in real-time as community expertise with these datasets grows, and so the legacy value of our programme is expected to extend well beyond any science case we can propose now. ILoTSS is designed to overlap with the Euclid sky area in order to maximise the multi-wavelength information at matched resolution, and will include full polarisation and time variability information across 7,600 deg². The proposed ILoTSS survey (in addition to finishing the remaining 10% of the LoTSS survey, which is < 10% of our time request) can be conducted with 8,500 observing hours, resulting in 30 PB of archived data products.

The full ILoTSS proposal is available here. If you are interested in joining the ILoTSS team please fill in this form.

Team members

The table below lists team members and their affiliations at the time of submission of the proposal.