Modeling gravitational waves from exotic compact objects

by Alexandre Toubiana

In the standard astrophysical paradigm, the only compact objects (with C>0.1) are black holes (BHs) and neutron stars (NSs). However, extensions of General Relativity (GR) and/or of the Standard Model can give rise to “exotic compact objects” (ECOs), which mimic the gravitational behavior of BHs and NSs to varying degrees. Thus, exotic compact objects can be difficult to distinguish from BHs and NSs in the inspiral phase of the binaries observed by gravitational-wave detectors, but significant differences may be present in the merger and post-merger signal.

In this talk, I will briefly review some models of ECOs and numerical simulations of non-BH binaries. Based on these results, I will present a toy model aiming to capture the main features of the full GW signal emitted by ECO binaries and use it to assess the detectability of such exotic signals with current and future detectors, and whether they can be distinguished from black hole binaries.

Testing the Kerr hypothesis: the examples of synchronisation and scalarisation

by Carlos A.R. Herdeiro

The Kerr hypothesis is that astrophysical black hole candidates are very special objects, with only two degrees of freedom and well described by the Kerr metric. Theoretically, this hypothesis is based on the uniqueness theorems for electro-vacuum. But in the presence of other types of matter or modified gravity are there any viable alternatives? In this talk I will illustrate some examples of black holes with “hair” that could co-exist with Kerr black holes, but emerge dynamically (and be preferred) at particular scales, either in General Relativity with ultralight bosonic matter or in modified gravity with higher curvature corrections, commenting on their theoretical and phenomenological differences (e.g. shadows) and on their phenomenological viability.

Magnetic fields, jets, and turbulence in the multimessenger era

by Philipp Moesta.  Meeting ID: 896 2772 7941 Password: 809669

Magnetic fields, turbulence, and jet-driven outflows play a critical role in core-collapse supernovae and compact-object mergers. These transients belong to the most luminous and energetic events observed in the universe and are key targets for time-domaiastronomy surveys. I will discuss the unique challenges in both input physics and computational modeling for these systems involving all four fundamental forces and highlight recent breakthroughs in full 3D simulations. I will pay particular attention to how these simulations can be used to reveal the engines driving these events and conclude by discussing what remains to be done in order to maximize what we can learn from current and future time-domain transient surveys.