The detection of gravitational waves (GWs) from a black hole binary merger by LIGO in 2015 started a new era in the exploration of the Universe. The addition of the Virgo antenna into the network led in 2017 to the detection of a neutron star binary merger that could be followed in electromagnetic signals, representing the beginning of multi-messenger astronomy. In 2019, IFAE joined the VIRGO Collaboration with significant contributions including commissioning activities in preparation for the O3 run, new hardware for the phase I upgrade of the Advanced Virgo (AdV+) and the physics analysis of the LIGO/Virgo data.
IFAE’s responsibilities within AdV+ relate to the crucial issue of understanding and controlling of the stray light, with an IFAE researcher coordinating the Virgo Stray Light Control (SLC) group. This activity capitalizes on IFAE’s experience in instrumentation and brings new challenges to the institute, including precise optics, ultra-high vacuum, and extends its expertise in infrared light detection. A first instrumented baffle was successfully installed in Virgo in spring 2021. Virgo plans a second upgrade including different mirrors equipped with second generation instrumented baffles designed and constructed by IFAE.
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; and the search for stochastic GW signals as probes of the early universe. It all resulted in several publications in top journals with IFAE PhD students as first authors (one PRL highlighted by the journal editors) and a strengthening of the connection between the GW and Theory group. IFAE contributed also to several other papers including the determination of the Hubble constant using O3 data, with an IFAE PhD student as corresponding editor.
IFAE plays a central role in the preparation of the third-generation Einstein Telescope (ET). IFAE is gaining international visibility with Mario Martínez being member of the ET Directorate and co-convener of the SLC group. In 2020-2021, he led the Spanish scientific community efforts resulting in Spain formally supporting the ET candidature as ESFRI infrastructure in Europe, and its official recognition in 2021. Mario Martínez is the European coordinator of the new Horizon-CSA INFRA-DEV ET-PP four-years project (2022 - 2026), corresponding to the preparatory phase of the ET experiment. At the end of 2022, Eugenio Coccia, new IFAE Director, joined the group. He is the Chair of the ET Collaboration Board.