Precise predictions for extreme mass ratio inspirals

Project Information

PreciseEMRIs

Grant agreement ID: 894881

DOI

10.3030/894881

Project closed

EC signature date 1 April 2020

Start date 1 September 2020

End date 31 August 2022

Funded under

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Total cost

€ 184 590,72

EU contribution

€ 184 590,72

Coordinated by

UNIVERSITY COLLEGE DUBLIN, NATIONAL UNIVERSITY OF IRELAND, DUBLIN
Ireland

Periodic Reporting for period 1 - PreciseEMRIs (Precise predictions for extreme mass ratio inspirals)

Reporting period: 2020-09-01 to 2022-08-31

Summary of the context and overall objectives of the project

The gravitational-wave sky was opened in the past few years by the first measurement of binary black-hole inspirals by the terrestrial gravitational-wave detectors LIGO, Virgo and KAGRA. A new chapter of this story is in the making as the European space agency approved a completely new type of detector of gravitational waves in 2017, the space-based Laser interferometer space antenna (LISA), as one of its three highest-priority missions for the 2030s. The scientific capabilities of LISA provide European science with a chance to be at the absolute cutting edge of gravitational-wave astronomy, to "see" new extreme phenomena in the Universe, and to deepen our understanding of Nature.

The sensitivity of LISA will be in the in the millihertz gravitational-wave band and it will observe new types of phenomena not seen by the terrestrial detectors. One of the most prominent and interesting sources seen in this band are the so-called extreme mass ratio inspirals (EMRIs), where a comparatively light, stellar-mass compact object spirals into a super-massive black hole. However, at the moment the precise predictions for the evolution of EMRIs are not ready, and this, if not rectified, would imply lower yields of valuable science to be obtained from the LISA mission. The subject of this project was to contribute to the development of these precise predictions, and to prepare for the discovery of new fundamental science with LISA and other gravitational-wave detectors.

In particular, the overall objectives of the project were (1) to develop theoretical and mathematical tools to incorporate various new corrections to the evolution of EMRIs and gravitational-wave inspirals in general, (2) to synergize these existing frameworks with previous models used for gravitational-wave inspirals, (3) to describe and incorporate various astrophysical effects on the inspirals such as the effect of plasma swirling in the environment, or the gravity of the surrounding galaxy, and (4) to delve deep into the mathematical equations describing the problem and try to find various tricks to deal with them more efficiently and accurately.

Even though the launch of LISA is more than 10 years in the future, the mathematical and technical challenge of providing the precise predictions is extremely non-trivial, and intense work must thus be initiated now. This research project not only contributed a significant part of the work needed, but it also allowed the Researcher to acquire the necessary skill and network to become an established scientist in the field of gravitational-wave theory that will be able to carry on in this ambitious research programme.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The PreciseEMRIs project worked towards its Research objectives within 4 Work Packages (WPs). WP1 was concerned with devising and implementing a particularly elegant system of expressing the solutions of the EMRIs and various corrections, the so-called Action-angle formalism, the results of which were expressed in 2 code releases, 1 paper, and 1 monograph chapter, and a number of ongoing collaborations. The WP2 was then concerned with the implementation of the inspiral with various astrophysical effects, such as the swirling of plasma in the environment, the rotation of the object, or the gravity of objects outside of the system. The results of WP2 were expressed in 3 conference papers, 3 regular papers, and a code release. WP3 was then concerned with the formulation of new speculative theoretical ideas about treating the evolution of the gravitational field and its coupling to the inspiralling bodies, and it resulted in 1 regular paper.

The last WP4 was concerned with Management, Communication and Dissemination of the results, in the framework of which 10 conferences were attended, at which 6 talks were given, 3 plenary discussions led or co-led, and 1 poster presented by the Researcher. Additionally, the Researcher gave 7 research seminars at various institutions across the world, gave 1 Outreach talk, and wrote 3 Outreach articles. He also left a significant online footprint, with a number of posts on social media, Q&A websites, and developed or co-developed 2 websites related to the Action. Additionally, the Researcher supervised or co-supervised 6 undergraduate research projects on topics related to the Action, thus disseminating the knowledge also in this way.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The PreciseEMRIs project pushed the frontiers of Extreme mass ratio inspiral theory and modeling. The Researcher provided new tools to model the inspirals and to include the perturbations due to and interactions with various astrophysical effects. The analytical model for resonances will soon be implemented in practical models what will be used to predict gravitational-wave signals by LISA. Already now we know of sources in the sky where sudden flashes of X-ray radiation indicate that interactions of inspirals with plasma may be happening, and this will be confirmed or disproved in the near future also thanks to the work of the PreciseEMRIs project. The acquired knowledge was spread throughout the community and even the general public through the ample networking and dissemination efforts of the Researcher even despite the challenges imposed by the COVID-19 pandemic. The knowledge will continue to be disseminated, used and developed in the future also thanks to the fact that the Researcher reached the maturity and excellence during the project that allowed him to secure a tenure-track position, where he will also use the mentoring experiences acquired during the Action to lead a small research team.

Discussion of environmental effects in EMRIs (video at https://doi.org/10.48660/21060081)

Conference photo from the 25th Capra meeting co-organized by Researcher.

Motivational talk "Physics: from microwaves to black holes" at Școala Excelsis, Chisinau, Moldova

Conference photo from the 2022 European Einstein Toolkit Meeting co-organized by Researcher.