New methods for a new gravitational-wave frontier
Lorenzo Speri has been awarded the GWIC-Braccini Thesis Prize.
Lorenzo Speri, a former PhD student in the Astrophysical and Cosmological Relativity department at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute, AEI) in Potsdam Science Park, has won an international award for his doctoral thesis. He developed statistical and computational tools to detect and interpret gravitational-wave signals that current and future observatories are designed to observe, especially in the nanohertz range probed by pulsar timing arrays, and the millihertz band targeted by the space-based LISA mission. The award comes with a certificate and a cash prize of US $1,000.
Gravitational wave astronomy has immense potential to address key questions in astrophysics and fundamental physics. Future observations from the space-based detector LISA, combined with current data from pulsar timing arrays (PTAs), will provide unprecedented insights into black holes, galaxy evolution, and fundamental physics. Speri’s thesis makes significant contributions to the field by tackling critical challenges in waveform modeling and data analysis for gravitational-wave signals in the millihertz (LISA) and nanohertz (PTA) frequency bands.
“I am delighted to have received this award, which is a great honor,” says Speri, who is now a Research Fellow at the European Space Agency (ESA). “One of the topics I researched for my thesis was systems in which a stellar-mass compact object spirals into a massive black hole. These Extreme Mass-Ratio Inspirals (EMRIs) offer unique opportunities to study strong-field gravity and black hole environments. However, their complex waveforms require computationally intensive analyses.” To address this challenge, Speri contributed to the development of a toolkit that enables rapid waveform generation and parameter inference. Furthermore, his thesis pioneers a detailed investigation of the effects of environmental factors, such as accretion disks, on EMRI signals. The results demonstrate that, while these effects can provide valuable insights into accretion disk physics, they can also significantly bias parameter estimation if not properly accounted for, even mimicking deviations from general relativity. This study has laid the groundwork for future research into black hole environments and their astrophysical implications.
From EMRIs to EPTA
In addition to EMRIs, Speri focused on nanohertz gravitational waves detected via pulsar timing arrays. He developed a novel pulsar ranking methodology that played a key role in selecting pulsars for the second data release of the European Pulsar Timing Array (EPTA). The thesis also contributes to the analysis of the stochastic gravitational-wave background (SGWB) and the search for individual supermassive black hole binaries. Speri’s study played a key role in the EPTA’s second data release and in refining strategies for future PTA observations.
The awardee
Lorenzo Speri earned his Bachelor's degree in Physics from the University of Trento, Italy, in 2018. He also studied abroad at the University of Oslo as part of the Erasmus+ program. He completed his Master's degree in Theoretical Physics at the University of Heidelberg in 2020. From 2020 to 2024, he pursued doctoral studies at the Max Planck Institute for Gravitational Physics, supervised by Jonathan Gair, group leader in the Astrophysical and Cosmological Relativity department. After earning his Ph.D. from Humboldt University in Berlin, he joined the European Space Agency as a Research Fellow. At ESA, he contributes to the development of LISA's data analysis infrastructure and coordinates interdisciplinary research across gravitational-wave science and statistical methodology.
The GWIC-Braccini Thesis Prize
The Gravitational Wave International Committee (GWIC) and the Friends of Stefano Braccini award an annual prize to outstanding PhD theses in the field of gravitational waves, the GWIC-Braccini Thesis Prize. Winning theses are chosen based on originality and creativity of the research, its importance to the field of gravitational waves and gravitational-wave detection, and the clarity of presentation. Each winner will receive a certificate of recognition and a prize of US$ 1,000. Speri’s thesis was selected from approximately two dozen nominations for the prize.
