ICTP-SAIFR Activities

Accurate modeling of compact binaries is essential for gravitational-wave detection and parameter estimation, with spin being an importante effect to include in waveform models. In this seminar, I will show how to derive new post-Newtonian (PN) results for the conservative aligned-spin dynamics at next-to-next-to-leading order for the spin3 and spin4 contributions, in addition to the next-to-leading order (NLO) spin5 and spin6 contributions. One approach we follow is the Tutti Frutti method, which relates PN and gravitational self-force (GSF) results through the redshift and spin-precession invariants, by making use of the simple dependence of the scattering angle on the binary mass ratio. However, an ambiguity arises at the NLO spin5 contribution, due to transcendental functions of the Kerr spin in the redshift; this is also the order at which Compton amplitudes calculations are affected by spurious poles. Therefore, we discuss an additional approach to determine the NLO spin5 and spin6 dynamics: using on-shell Compton amplitudes dictated by homogeneous solutions of the Teukolsky equation, the later solved non-perturbative in terms of the Nekrasov-Shatashvili Function.

I review the state of the art of modern approaches to gravitational wave physics that leverage ideas and tools from scattering amplitudes and quantum field theory to tackle the gravitational binary problem in (classical) general relativity.

The 3-body problem poses a longstanding challenge in physics and celestial mechanics. Despite the impossibility of obtaining general analytical solutions, statistical theories have been developed based on the ergodic principle. This assumption is justified by chaos, which is expected to fully mix the accessible phase space of the 3-body problem.We probed the presence of regular (i.e. non-chaotic) trajectories within the 3-body problem and assessed their impact on statistical escape theories.Our analysis reveals that regular trajectories occupy up to 37% of the phase space, and their outcomes defy the predictions of statistical escape theories. Our findings underscore the challenges in applying statistical escape theories to astrophysical problems, as they may bias results by excluding the outcome of regular trajectories. This is particularly important in the context of formation scenarios of gravitational wave mergers, where biased estimates of binary eccentricity can significantly impact estimates of coalescence efficiency and detectable eccentricity.Based on 2403.03247

The emergence of synchronization and its general features are of particular interest to scientists working on several areas, such as physics, social sciences and biology. From neurons to population dynamics and fireflies, nature showcases several examples of synchronized and collective behavior. The paradigmatic model to investigate synchronization was proposed by Y. Kuramoto in 1975, with several extensions and generalizations being studied in the years that followed. This colloquium aims at overviewing some interesting modifications of this model such as frustration, external forces and higher order interactions, in addition to discussing some fundamental aspects of synchronization phenomena. Finally, I will comment on some contributions from our research group and some prospects on this subject