Plenary Talks - Abstracts

Katelyn Breivik, Flatiron Institute

Piecing together the formation and evolution of compact objects in binaries

The observation of gravitational waves from 50 pairs of merging black hole and neutron star binaries by the LIGO-Virgo Collaboration offers the first glimpse of the potential to use these populations as tools to study the formation and evolution of compact objects and their stellar progenitors. However, even with dozens of mergers, the dominant formation pathways for merging compact-object binaries remains unconfirmed. Furthermore, even with third generation ground-based detectors, which could potentially discover merging binary black holes across all redshifts out to the epoch of reionization, such mergers only account for a tiny fraction of all black holes formed in the Universe. In this talk I will discuss opportunities to probe the formation environments and scenarios of compact objects using observations from ground- and space-based GW detectors with a particular focus on the complementary source information each detector provides. I will also discuss how GW populations play a role in the larger landscape of observations of compact objects in stellar binaries.

Imogen Coe, Ryerson University

Uncomfortable Truths & Inclusive Excellence in Science
Academic science reflects the context in which science is conducted.  Thus, the academic scientific enterprise struggles with privilege, racism, sexism, ableism, and homophobia, in Canada, as around the world.  In this talk, I will address the uncomfortable and sometimes difficult conversations we must have in order to get to the real work of identifying and removing barriers that limit access and engagement in the scientific enterprise for the full diversity of humanity.  We live within a myth of meritocracy in academia and are failing to achieve our full potential as a sector.  Moving on from self-awareness as individuals or organizations, we can start to identify the tools and skill sets that individuals and collectives need in order to create cultures of care that achieve inclusive excellence and the very best scientific outputs.  

Eva Hackmann, University of Bremen

Geodesic motion in relativistic astrophysics

Since the advent of (relativistic) astrophysics it has been one of the most important tasks to study the motion of freely falling particles, both from a purely academic and an observational point of view. In this presentation I review the solution methods for the equations of motion of particle-like objects and light within a wide variety of spacetimes. Moreover, we take a closer look on the importance of special orbits for phenomena like black hole shadows or accretion discs.

Justin Vines, Albert Einstein Institute

Progress and prospects in the mingling of quantum-scattering-amplitudes, post-Minkowskian, post-Newtonian, and self-force calculations

Recent years have seen a surge of progress in post-Minkowskian (PM, weak-field but arbitrary-speed) approximation methods for the gravitational two-body problem, complementing and reorganizing the still much further developed post-Newtonian (PN, weak-field and slow-motion) approximation.  This has been driven by simplifying insights, powerful computational tools, and new results coming from the study of on-shell scattering amplitudes in quantum field theories and their classical limits.  We will review some of these developments, focusing on the particularly impactful observation (ultimately also understandable from a purely classical perspective but born of the dialog with quantum amplitudes) that certain PM and PN results for arbitrary mass ratios can be determined from surprisingly low orders in the extreme-mass-ratio/self-force expansion.

Bernard Whiting, University of Florida

Capra Wrap-up, and the road ahead

In the last quarter century, Capra has grown from a mere handful of people to a fully international meeting, which now represents a large diversity of interests.  In that time, much progress has been made: many aspects of the first order problem are now in hand, and a multitude of techniques has been formulated for eventually use in full EMRI waveform generation.  Yet, much needs to be done, most notably at second order.  In Capra meetings of the past, we have often recognized the need to reach out to the younger generation.  I think efforts in that direction have clearly been effective.  At some Capra meetings, specific problems have often taken focus, both in discussions at the meeting, and in the work that evolves over the coming year.  From experience, we know this approach has also clearly paid off.  From the discussions that have taken place here, we need to go forward with specific goals for the year ahead, drawing wherever possible on the diversity we now have before us.  Great things can be achieved if great problems are tackled.  What have we formulated to work on as a community together before we can meet again in 2022?