What we are working on
Research programme
The programme is organized into three work packages (WP): the theory of wave-optics lensing, the search for lensed gravitational waves, and their application to fundamental physics.
The three work packages run in parallel. WP1 supplies the lens models that WP2 searches for and WP3 interprets. The loop closes by informing back the necessary theoretical developments.
This page says what the project is working on and how far each piece has got. The division into work packages and the task codes come from the funded proposal, and they are kept because a great deal cross-references them, but the research itself moves: expect the descriptions here to change as results come in. For the physics behind them (what these phenomena are and what they can measure) see the science topics, which each task links to.
WP1
Wave-optics theory
The theory and numerical methods for wave-optics lensing: diffraction by populations of microlenses, and lensing by ionized plasma. Everything the other two work packages need in order to model realistic lenses.
Microlensing diffraction
Quantify how populations of microlenses and the macroscopic potential of their host galaxy (magnification, proximity to caustics) shape a lensed signal. Reaching the required performance means developing new algorithms that can reliably tackle a large microlens population. Explore the role of microlens populations in astrophysical predictions.
- Public microlensing extensions of the GLoW code
- Cross-validation against independent wave-optics codes
Plasma lensing
Extend the framework to lensing by ionized matter. Plasma lensing produces dispersive terms by which fast radio bursts probe otherwise elusive baryonic matter, with applications to pulsar timing and the interstellar medium. Develop methods for multi-plane lensing that can account for deflection and dispersion at the location of the main lens, as well as the source's galaxy and the Milky Way.
WP2
Discovery and interpretation of lensed gravitational waves
Turning the theory into search results. Waveform models for microlensing signatures, population-level analyses, and accelerated inference to keep up with upcoming data.
Microlensing searches
Search for lensing signatures in gravitational-wave data through microlensed waveforms. The waveform models account for stochastic fluctuations of the amplification and their correlation with macroscopic quantities (density and mass function of the lenses and the external potential). Develop methods to incorporate lensing signatures into a coherent population analysis.
- Microlensed waveform models tested against public LVK catalogs
- Population model with lensing effects
Microlensing · Data analysis · Distant and strong-field sources
Accelerated inference
Lensing analyses multiply the parameter space, and the number of events is growing. Machine-learning inference, building on DINGO, makes joint and low-latency analyses tractable, allowing efficient inference over large source catalogs.
- Trained network for rapid analysis and identification of lensed signals A model for the isolated point lens is public.
WP3
Fundamental physics
What lensed coherent sources reveal about the constituents of the Universe: the small-scale distribution of dark matter, and the impact of dark energy on the propagation of gravitational waves.
Dark-matter searches
Characterize diffraction by dark-matter objects and subhalos, and produce lensing constraints from available data. Connect the theory and analysis results to well-motivated dark-matter theories (self-interacting and ultra-light dark matter, dressed primordial black holes) including collective effects and addressing the distinguishability from stellar fields. Results also translate into limits on the primordial power spectrum.
- Lensing constraints on dark-matter objects from current data
- Entries in the community repository of extended dark-matter object limits
Gravity and dark energy
Develop the theory of gravitational-wave propagation on inhomogeneous space-times beyond Einstein's theory. Extract new constraints from public data and use them to set new limits on theories of dark energy.
- A parameterized framework for modified gravitational-wave lensing
- Public likelihoods for cosmological analyses
External collaborations
An ERC Synergy Grant building the theoretical framework and tools to interpret gravitational-wave observations, from the current LIGO–Virgo–KAGRA network to Einstein Telescope, Cosmic Explorer and LISA. We collaborate closely with GWSky members based at the AEI Potsdam, one of the nodes of the project.