Grav19 April 8th–12th, 2019, Cordoba,´ Argentina Monday Tuesday Wednesday Thursday Friday 9:00-9:50 J. Pullin P. Ajith 8:45 F. Pretorius D. Siegel A. Perez´ 10:00-10:30 C OFFEE yLive streaming EHT/ESO C OFFEE 10:30-11:20 I. Agullo J. R. Westernacher 11:00 Coffee/discussion I. Racz´ J. Peraza 11:30-12:20 H. Friedrich O. Sarbach #12:00. S Liebling/L.Lehner F. Beyer F. Carrasco 12:20-14:00 **Reception Lunch** LUNCH 14:00-14:50 J. Frauendiener A. Rogers J. Jaramillo O. Moreschi 14:50-15:10 R. Gleiser B. Araneda A. Acena˜ C. del Pilar Quijada 15:10-15:30 T. Madler¨ L. Combi A. Giacomini E. Eiroa 15:30-15:50 P. Rioseco J. Bad´ıa enjoy I. Gentile G. Figueroa Aguirre 15:50-16:10 C OFFEE your C OFFEE 16:10-16:30 J. Oliva F. Canfora´ free M. Arganaraz˜ M. Ramirez 16:30-16:50 M. Rubio A. Petrov afternoon F. Abalos O. Fierro Mondaca 16:50-17:10 O. Baake G. Crisnejo P. Anglada M. J. Guzman´ 17:10-17:30 N. Miron´ Granese N. Poplawski 18:30-20:00 **Wine and Cheese** ?? 19:00hs. Jorge Pullin ?Gabriela Gonzalez: Public Lecture (Charla Publica,´ libre y gratuita). Friday, April 5: 20.00 HS at Observa- torio Astronomico´ de Cordoba:´ LAPRIDA 854, Auditorio MIRTA MOSCONI. ?? Jorge Pullin: La telenovela de las ondas gravitacionales: desde Newton en 1666 hasta Estocolmo 2017, Martes 9, 19:00HS en el SUM de la Plaza Cielo Tierra (Bv. Chacabuco 1300). y 10:00-1100. Live announcement from the Event Horizon Telescope/ESO collaboration. # Steve Liebling talk followed by the tlak of Luis Lehner. MORNING TALKS MONDAY 8 Loop quantum gravity overview and recent developments J. Pullin Louisiana State University. We give a non technical summary of loop quantum gravity and discuss applications in cosmology and black holes. Electromagnetic Duality Anomaly in Curved Spacetimes Ivan Agullo Louisiana State University, University of Valencia It is well known that the source-free Maxwell equations are invariant under electric-magnetic duality rotations. This is true even in the presence of an arbitrary gravitational background field. I will discuss in this talk whether this symmetry is maintained when the electromagnetic field is quantized. The answer is in the affirmative in the absence of gravity, but not necessarily otherwise. As a consequence, the net polarization of the quantum electromagnetic field fails to be conserved in certain spacetimes, as for instance in presence of mergers of compact objects. I will discuss the analogy with the well-known chiral anomaly spin 1/2 fermions, and potential physical consequences. Einstein-lambda-matter flows and asymptotic simplicity. Helmut Friedrich Max-Planck-Institut fur¨ Gravitationstheorie (AEI) The recently observed accelerating expansion of our cosmos seems to be well modeled by solutions to the Einstein equations with cosmological constant in four space-time dimensions. In this talk I consider these equations coupled to various matter fields and discuss the behaviour of the solution at future time-like infinity in detail. It will be seen that there are massive matter fields that admit the construction of and an unimpeded evolution of the fields across a smooth conformal extensions at future time-like infinity. We also consider situations where the matter fields impose obstructions to a smooth conformal extensibility of the solution. TUESDAY 9 Probing strong gravity using gravitational wave observations P. Ajith International Centre for Theoretical Sciences, TIFR, Bangalore, India Gravitational wave observations by LIGO and Virgo provide a unique laboratory to study gravity in a regime inaccessible to traditional astronomical observations and laboratory tests. These observations enable tests of the validity of general relativity, the existence of black hole horizons and the nature of compact objects. The large number of binary merger events expected in the near future, including some “golden” events, will significantly improve the precision of these tests. This talk will discuss the results from the recent observations and will give a flavor of the future prospects and challenges. Expositor: J. R. Westernacher-Schneider Multimessenger Seismology of Core-Collapse Supernovae J. R. Westernacher-Schneider, E. O’Connor, E. O’Sullivan, I. Tamborra, M.-R. Wu University of Arizona Asteroseismology of the inner core of a core-collapse supernova is possible with gravitational waves and neutrinos. We show that the excitation of a linear mode of the core can imprint itself on the neutrino luminosity, provided the mode amplitude is large enough in the vicinity of the neutrinosphere. This can occur with sufficient rotation. Thus, neutrinos carry information about the mode excitation at a radius of 60-70 km, whereas gravitational waves probe deeper. Well-posed Cauchy formulation for Einstein-aether theory Olivier Sarbach Universidad Michoacana de San Nicolas´ de Hidalgo, Mexico.´ We discuss the well-posedness of the Cauchy problem of vacuum Einstein-aether theory. The latter is a Lorentz- violating gravitational theory consisting of General Relativity with a dynamical timelike “aether” vector field, which selects a preferred time direction at each spacetime event. The Einstein-aether action is quadratic in the gradient of the aether, and thus yields second-order field equations for the metric and the aether. However, in general the structure of these equations is rather complicated, and this makes it difficult to formulate a well-posed Cauchy problem away from the simple case of linearized perturbations over flat spacetime. In this talk we employ a first-order formulation of Einstein-aether theory in terms of projections on a tetrad frame and show that under suitable conditions on the coupling constants of the theory, the resulting evolution equations can be cast into strongly or even symmetric hyperbolic form, and therefore they define a well-posed Cauchy problem. WEDNESDAY 10 Testing General Relativity with Black Hole Mergers F. Pretorius Princeton University, USA Testing the predictions of general relativity in the dynamical strong-field regime, in particular black holes and their dynamics, has only recently become possible with LIGO/Virgo observations of black hole mergers. I will review some of the tests that have been performed to date. However, one obstacle to extracting the most stringent constraints possible from the data are the lack of predictions of what the coalescence phase of black hole mergers should like in gravitational wave emission within modified gravity theories (or theories that claim exotic alterna- tives to black holes). To make things worse, there are doubts to how well-posed many modified gravity theories, than in principle might offer interesting merger dynamics, are. One such theory is Einstein-dilaton-Gauss-Bonnet (EdGB) gravity. I will describe early results beginning to address the well-posedness of EdGB gravity within the dynamical strong-field regime. We restrict attention to gravitational collapse in spherical symmetry, and show for sufficiently strong coupling EdGB gravity is not well-posed from the perspective of the Cauchy initial value problem. Press Conference on First Result from the Event Horizon Telescope The European Commission, European Research Council, and the Event Horizon Telescope (EHT) project will hold a press conference to present a groundbreaking result from the EHT. Extensions to GR, challenges and possible resolutions L. Lehner Perimeter Institute for Theoretical Physics, Canada. Theories that are extensions to GR often involve severe problems which can stand in the way of understanding them or interpret lessons drawn at the linear level on the original theory. This talk will discuss some examples and options to either constrain viable options or, alleviate their possible pathologies. Alternatives to Binary Black Hole Mergers in GR Steven L. Liebling Long Island University. The mergers of many binary black holes (BBH) have already been observed by LIGO, with many more expected when LIGO comes back online soon. Such observations serve to constrain and test our theory of gravity, and, as such, it makes sense to study alternatives to the general theory of relativity (GR). I will discuss BBH mergers within two models that move beyond GR. The first is Einstein-Maxwell-dilaton which adds a vector and a scalar field to the gravitational degrees of freedom. the flatspace sector, Maxwell-dilaton, represents a simpler, yet still nonlinear, model which also has interesting dynamics. The second is an ad-hoc model that considers possible fluctuations near the black hole horizons that might arise from a quantum theory of gravity. THURSDAY 11 Multimessenger astrophysics and cosmic nucleosynthesis Daniel M. Siegel Columbia University, USA The recent detection of the binary neutron star merger GW170817 by advanced LIGO and Virgo and its fireworks of electromagnetic counterparts across the entire electromagnetic spectrum marked the beginning of multi-messenger astronomy and astrophysics with gravitational waves. Such detections combined with observations of other prime targets of transient astronomy hold the premise to understand the cosmic origin of most elements in the periodic ta- ble after decades of speculation. In this talk, I will review current advances in both observations and the theoretical modeling of neutron star mergers and core-collapse supernovae in the context of heavy element nucleosynthesis, and discuss challenges and opportunities for the coming years. On the use of evolutionary methods in spaces of Euclidean signature Istvan´ Racz´ University of Warsaw and Wigner RCP, Budapest Two examples of physical interest will be presented. Both, contrary to the folklore, demonstrate that evolutionary methods may also play significant role in spaces of Euclidean signature. First, the propagation of the constraints is considered. It is shown that once a clear separation of the evolutionary and constraint equations is done, the subsidiary equations satisfied by the constraint expressions form a first order symmetric hyperbolic system re- gardless whether the ambient Einsteinian space is of Lorentzian or Euclidean signature.