GW231123: a magnified and diffracted merger
The first compelling candidate for a black-hole merger magnified and diffracted by a compact object of 190–850 M☉.
Miguel Zumalacárregui
Exploring gravitation, cosmology & astrophysics
I lead a research program that uses the lensing of gravitational waves and light to illuminate some of the Universe's darkest secrets: black holes beyond the detector horizon, dark-matter structures and the dynamics of dark energy. I work across theory, phenomenology, algorithmic development and the analysis of real gravitational-wave and cosmological data.
News
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NewThe GLOW project website went live, with the science programme, the team and the software and data releases of the ERC project. glow-astro.org
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NewOur analysis of GW231123 as a magnified and diffracted black-hole merger, the first compelling candidate of its kind, was published in The Astrophysical Journal Letters. ApJL 1008, L12 · AEI press release · Cosmology Talk
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NewBeyond-Horndeski (GLPV) theories and the conformally coupled Galileon became part of the public hi_class code, widening the set of dark-energy and modified-gravity models whose cosmological observables it can compute. hiclass-code.net
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NewA machine-learning method for inferring microlensed gravitational waves, fast enough to make wave-optics analysis routine, appeared in Physical Review D. PRD 113, 104073
Current roles
- Principal Investigator, GLOW ERC Consolidator Grant, 2026–2031
- Ramón y Cajal Fellow IFT Madrid · Group Leader, ACR Department, AEI Potsdam
- Senior Co-Chair, LISA Cosmology Working Group Since 2025
- Co-Lead, Euclid Gravitational Waves SWG Since 2025
Featured recent results
Stochastic diffraction with LISA
Populations of 10–104 M☉ dark-matter halos leave a coherent diffraction imprint, potentially within LISA's reach.
Quasi-periodic lensed starlight could reveal supermassive black-hole binaries and their orbital dynamics. Editors' Suggestion
Research program
My research addresses the dark contents of the Universe from two directions: wave-optics lensing (diffraction and interference) of gravitational waves, and cosmological tests of gravity and dark energy. Both rely on current observatories and inform the preparation for upcoming ones.
Wave-optics lensing phenomena
Diffraction and interference imprint the mass distribution of a lens directly on a gravitational-wave signal. We build the theory and the methods that read it back out.
Dark matter and compact structures
Lensing is one of the few probes sensitive to dark matter on sub-galactic scales, which may hold the key to distinguishing its fundamental nature.
Strong-field and multi-messenger lensing
Black holes are excellent lenses, and binary systems lead to rich signatures. Combining lensed waves with lensed light constrains the lens far better than either alone.
Gravitational-wave propagation and dark energy
A lens breaks the symmetry of the background, letting waves couple to new fields. Birefringence and dispersion become tests of cosmological gravity that need no electromagnetic counterpart.
Methods, inference and software
Fast wave-optics solvers, statistical searches and the public codes GLoW and hi_class: the results are reproducible by anyone.
Cosmology and gravity theories
Cosmological tests of dark energy and the scalar–tensor theories behind them. This line preceded the lensing work and continues alongside it, and much of the theoretical machinery came from it.
Scientific coordination and future observatories
LISA, Euclid and the detectors that follow them will decide what lensing can measure. Part of my work goes into preparing those missions, and into making sure lensing has a place in their science cases.
Group, projects and software
The group
Postdocs, PhD and Master's students working on wave-optics lensing, dark matter and gravitational-wave propagation, plus visitors, former members and information for applicants.
Projects & funding
GLOW (ERC Consolidator, 2026–2031), With Einstein on Crooked Paths and the Ramón y Cajal program, which I lead, plus a collaborator role in the GWSky ERC Synergy Grant.
GLoW and hi_class
Two public codes maintained for the community: a wave-optics lensing package, and an Einstein–Boltzmann solver for dark energy and modified gravity.
Start here
A short introduction to gravitational-wave lensing, for a general audience. More scientific presentations are on the Talks page; public lectures, popular writing and press are under Outreach.
Supported by
Previously supported by
