Artist’s impression of a gravitational wave

IFAE Research Groups

Gravitational Waves Group

  • Gravitational Waves Group

    In 2019, IFAE initiated a long-term experimental involvement in the Virgo ground-based Fabry-Perot interferometer (Cascina, Italy), with the emphasis of studying fundamental physics using GWs.

    The Gravitational Wave Group is led by Mario Martínez

    Introduction

    The detection of gravitational waves (GWs) from a black hole (BH) binary merger by LIGO in 2015 represented the beginning of a new era in the exploration of the universe. Shortly afterwards, the addition of the Virgo antenna into the network led to the detection of a neutron star (NS) binary merger that could be followed in electromagnetic signals, representing the beginning of multi-messenger astronomy. The new O3 observation run in 2019-2020 witnessed an increase of almost an order of magnitude in the detection rates. Some observed events brought new challenges in understanding the population of BHs from the canonical stellar evolution models. Altogether, GW astronomy has already radically changed the stage for several areas of physics, from astrophysics to particle physics. Nowadays, the study of GWs and BHs is at the forefront of the research in fundamental physics, as it has been recognized by three Nobel prizes in 2017, 2019 and 2020, and is a major item in both HEP and APPEC future roadmaps. The research on GWs has been explicitly included in the Spanish Strategic plan for Science, Technology and Innovation (EECTI) 2021-2027.
    Aerial view of Virgo
    Aerial view of Virgo Credit: The Virgo Collaboration
    IFAE is a member institution inside the VIRGO collaboration and this opens a new long-term research line in IFAE related to GWs detection using terrestrial interferometry.

    Instrumentation

    IFAE responsibilities within Advanced Virgo (AdV+) relate to the understanding and control of the stray light inside the interferometer, considered a limiting factor for its sensitivity, with an IFAE researcher already coordinating the Virgo Stray Light Control group. IFAE is instrumenting very sensitive and delicate parts of Virgo (the areas covered by baffles surrounding the suspended mirrors under vacuum) with many photo sensors to monitor and control the stray light propagating throughout the interferometer.

    Rear-side view of a suspended mirror
    The image shows the rear-side view of a suspended mirror. The coating reflects the Virgo near-infrared laser beam, but is transparent in the visible range. A scientist is finally releasing the safety stops used during installation. The 42kg-mass mirror is suspended from four thin fused-silica fibres, which are bonded to the sides of the mirror. Credit: EGO/Virgo Collaboration/Perciballi

    Physics program

    The group has put in place a strong physics program with three main pillars:

    • the search and study of compact binary coalescence events with emphasis on fundamental physics related to tests of General Relativity and dark matter searches;
    • the use of GW for cosmological tests;
    • the search for stochastic GW signals as probes of the early universe.

    A strong experiment–theory collaboration within IFAE has been established for this purpose. In addition, the group is a main actor in the understanding of the interferometer using detailed simulations.

  • Group Members

    Gravitational Waves Group

    Staff Researchers

    • Matteo Cavalli-Sforza

      Matteo Cavalli-Sforza

    • Eugenio Coccia

      Eugenio Coccia

    • Andrew Lundgren

      Andrew Lundgren

    • Mario Martínez

      Mario Martínez

    • Lluïsa Mir

      Lluïsa Mir

    Visitor Researchers

      Postdoc Researchers

      • Machiel Kolstein

        Machiel Kolstein

      • Jam Sadiq

        Jam Sadiq

      PhD Students

      • Catalina Miritescu

        Catalina Miritescu

      • Dounia Nanadoumgar Lacroze

        Dounia Nanadoumgar Lacroze

      • Sakshi Satish Madekar

        Sakshi Satish Madekar

      • Leonardo Toti

        Leonardo Toti

      • Elisabet Vallejo Pagès

        Elisabet Vallejo Pagès

    • International Collaborations

      Gravitational Waves Group

      Aerial view of Virgo

      Virgo

      Virgo

      Virgo is a Gravitational Wave detector, hosted by the European Gravitational Observatory (EGO), near Pisa, Italy.

        Pisa, Italy
      LIGO Livingston

      LIGO

      Laser Interferometer Gravitational-wave Observatory

      LIGO runs two observatories - interferometers with two 4km-long arms arranged in the shape of an “L” - at Livingston and Hanford in the United States. The LIGO Scientific Collaboration (LSC) comprises over 1,200 scientists from more than 100 institutions in 18 countries,

        Livingston & Hanford, USA
      Einstein Telescope

      ET

      Einstein Telescope

      The Einstein Telescope (ET) is a proposed underground infrastructure to host a third-generation, gravitational-wave observatory. The Einstein Telescope will achieve a greatly improved sensitivity by increasing the size of the interferometer from the 3km arm length of the Virgo detector to 10km, and by implementing a series of new technologies.

       
    • Research Projects

      Gravitational Waves Group

      HORIZON-INFRA-DEV, 2021

      Preparatory Phase for the Einstein Telescope Gravitational Wave Observatory (ET-PP)

      Einstein Telescope will be the European Third-Generation Gravitational Wave Observatory, designed to observe the Universe by covering the whole spectrum observable from Earth with interferometric GW detectors.The ET preparatory phase (ET-PP) will address a number of fundamental prerequisites for the approval, construction and operation of the Einstein Telescope. Project coordinated by IFAE.

      Aerial view of Virgo

      Proyectos I+D Generación de Conocimiento, 2020

      Física de ondas gravitacionales interferometros terrestres

      The IFAE group participates in the Virgo experiment to study gravitational waves, including hardware, software/simulations, physics analysis, operations and commissioning of the interferometer, and R&D for future facilities. Their project includes building instrumented baffles for Virgo to monitor stray light distribution, contributing to commissioning and calibration of the interferometer, and conducting physics research such as searches for binary systems and measuring the Hubble constant using GWs as standard sirens.

        H2020-MSCA-RISE, 2020

        Probes of new physics and technological advancements from particle and gravitational wave physics experiments (PROBES)

        The PROBES project will investigate various aspects of particle physics and cosmology, including color confinement, dark matter, neutrino oscillations, and gravitational waves. The project will involve collaborations with international laboratories and the development of cutting-edge experiments to explore these phenomena.

        Aerial view of Virgo

        H2020-ICT, 2016

        NEWS

        NEWS aims to enhance collaboration among European, US, and Japanese research institutions in key areas of fundamental physics. This includes the operation of the largest gravitational wave observatories, a gamma-ray telescope, X-ray polarization detectors, particle accelerators, and innovative detectors to open new 'windows' in fundamental physics.

        • Publications

          Gravitational Waves Group

        • Group News

          New leadership

          Einstein Telescope Collaboration appoints new leadership

          March 19, 2026

          Michele Maggiore has been selected as its new Spokesperson, with Angélique Lartaux appointed Deputy Spokesperson.

          New publication

          New publication by the Gravitational Waves and the Theory groups

          February 20, 2026

          Search for peak structures in the stochastic gravitational-wave background in LIGO-Virgo-KAGRA O1-O4a datasets

          Gravitational Waves

          Spain strengthens its participation in major gravitational-wave infrastructures

          December 10, 2025

          The Spanish Ministry of Science, Innovation and Universities has allocated new funding to Spain’s participation in major international gravitational-wave infrastructures, with the Institut de Física d’Altes Energies (IFAE) designated as the institution through which these contributions will be channelled.

          Results

          LIGO–Virgo–KAGRA complete their richest gravitational-wave observation run to date

          November 18, 2025

          The LIGO–Virgo–KAGRA (LVK) Collaboration has announced the completion of O4, the most productive gravitational-wave observation run so far, yielding an unprecedented number of candidate events and high-quality data for the scientific community.

          Results

          LIGO, Virgo and KAGRA observed 'second generation' black holes for the first time

          October 29, 2025

          Researchers from the Institut de Física d’Altes Energies (IFAE), through its Gravitational Waves group, participate in the LIGO–Virgo–KAGRA collaboration that has reported the first observational evidence of candidate second-generation black holes. The analysis of two gravitational-wave signals reveals binary systems with unusual mass ratios and spin configurations, opening a new window on black-hole formation in dense astrophysical environments.

          New Member

          New member in the Gravitational Waves group

          October 29, 2025

          Jam Sadiq is joining the Gravitational Waves group as a PostDoctoral researcher