EOB@Work24

10 Jun 2024, 09:00 → 12 Jun 2024, 18:00 Europe/Berlin

TPI, FSU Jena

The effective-one-body (EOB) framework is a powerful analytical tool for the solution of the two-body problem in general relativity and beyond. The EOB approach is used to design waveform models for gravitational-wave (GW) astronomy and more in general to explore the two-body dynamics incorporating perturbative and numerical results in a unified framework.

EOBAtWork is the third of a series of workshops aimed at starting a collaborative research effort at the frontiers of EOB development. The workshop is informal and technical. It alternates discussions with hands-on sessions.

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The topic of the 2024 workshop is:

The interplay between conservative and dissipative dynamics

Recent works suggests that semi-analytical EOB models approach the accuracy threshold of numerical relativity. As such, even (apparently) minor modeling choices can have significant impact on waveforms.
In this workshop we will focus on one specific aspect of the EOB framework: the modeling of the GW flux and its interplay with the conservative dynamics.

In particular, we will discuss:

• Pathways to include PM information in the conservative EOB sector;
• The modeling of horizon absorption in the comparable and extreme-mass-ratio limits;
• Synergies and requirements from numerical relativity

Additionally we will have a special evening lecture:

"EOB - offspring of the PN ADM formalism" by Prof. Gerhard Schäfer

on Tuesday at 16:30.

A3-Poster_EOBWork2024-def.pdf

Monday 10 June

Status and challenges

Convener: Dr Rossella Gamba

Status and challenges

Convener: Simone Albanesi (Friedrich-Schiller-Universität Jena)

10:00 Coffee break

Hands on: working groups formation

12:00 Lunch

Hands on: working groups

15:00 Coffee break

Hands on: working groups

Results & discussion

Tuesday 11 June

Hands on: working groups

10:30 Coffee break

Hands on: working groups

12:00 Lunch

Hands on: working groups

14:30 Coffee break

Hands on: working groups

Results & discussion

1 Evening Lecture: EOB - offspring of the PN ADM formalism

Hamiltonian formalisms provide powerful tools for the computation of approximate analytic solutions of the Einstein field equations. The post-Newtonian computations of the explicit analytic dynamics and motion of compact binaries are discussed within the most often applied Arnowitt-Deser-Misner formalism. The obtention of autonomous Hamiltonians is achieved by the transition to Routhians. Order reduction of higher derivative Hamiltonians results in standard hamiltonians. Tetrad representation of general relativity is introduced for the tackling of compact binaries with spinning components. Compact objects are modeled by use of Dirac delta functions and their derivatives. Consistency is achieved through transition to d-dimensional space and application of dimensional regularization. At the fourth post-Newtonian level, tail contributions to the binding energy show up for the first time. The conservative dynamics of binary systems finds explicit presentation and discussion through the fifth post-Newtonian order for spinless masses. For masses with spin Hamiltonians are known through (next-to)3 -leading-order spin-orbit and spin-spin couplings as well as through next-to-leading order cubic and quartic in spin interactions. Parts of those are given explicitly. Tidal-interaction Hamiltonians are considered through (next-to)2 -leading post-Newtonian order. The radiation reaction dynamics is presented explicitly through the third-and-half post-Newtonian order for spinless objects, and, for spinning bodies, to leading-order in the spin-orbit and spin1-spin2 couplings. The most important historical issues get pointed out.

Speaker: Prof. Gerhard Schäfer

17:30 Social BBQ

Wednesday 12 June

2 Comparing effective-one-body and gravitational self-force results for black hole binaries with a spinning secondary

We present the first comparison of waveforms evaluated using the effective-one-body (EOB) approach and gravitational self-force (GSF) theory for inspiralling black hole binaries with a non-spinning primary and a spinning secondary. We explore the performance of two gauge choices for the gyro-gravitomagnetic functions entering the spin-orbit sector within the EOB dynamics, the standard "Damour-Jaranowski-Schäfer" (DJS) gauge and a second one labelled anti-DJS. By drawing comparisons both in the time and in the frequency domain, we find that the anti-DJS gauge brings the EOB spin contribution at 1st post-adiabatic order closer to the GSF one.

Speaker: Angelica Albertini

Hands on: working groups

10:30 Coffee break

Hands on: working groups

12:00 Lunch

Status and challenges: individual group reports

14:00 Coffee break

Status and challenges: individual groups report

Results & discussion: achievements and future steps