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Dr Alicia Sintes (Balearic Islands University)01/09/2025, 09:00talk
Over the past ten years, the LIGO and Virgo observatories—and now KAGRA—have transformed gravitational-wave detection from an audacious dream into a powerful and routine window onto the cosmos. This talk will retrace that remarkable journey, beginning with the historic first detection of GW150914 on September 14, 2015—a breakthrough that inaugurated gravitational-wave astronomy and forever...
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Katerina Chatziioannou (California Institute of Technology)01/09/2025, 09:50talk
The spins of black holes in binaries observed with gravitational waves are an essential probe of physics on multiple scales, from the astrophysical formation environments of compact binaries to fundamental physics. At the same time, the imprint of spin on the observed signals is weak, making constraints more challenging compared to the other key property of black holes, namely their mass. I...
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Prof. Claudia De Rham (Imperial College London)01/09/2025, 11:00talk
I will discuss the interplay between the behaviour of particle physics and gravity as we observe them in our “every day”-experiments and observations, and the embedding of these effective description within a meaningful quantum theory of gravity, emphasizing the subtle relation to causality.
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Eleni-Alexandra Kontou (King's College London)01/09/2025, 11:50talk
The classical Penrose inequality (PI), a relation between the ADM mass and the area of any cross section of the black hole event horizon, was introduced as a test of the weak cosmic censorship: if it fails, the trapped surface is not necessarily behind the event horizon and a naked singularity could form. Since that original derivation, a variety of proofs have developed, mainly focused on the...
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Georgios Antoniou (INFN Rome & Sapienza University of Rome)01/09/2025, 12:25talk
We will discuss the framework of quadratic gravity where both General Relativity (GR) and "hairy" black holes coexist. We explore the phenomenology of the solutions and go over the regime of stability. We will then examine quadratic gravity as a candidate for beyong-GR effects in current and upcoming gravitational wave (GW) observations.
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Prof. Andrew Tolley (Imperial College London)01/09/2025, 15:00talk
There exists a duality in the form of a non-local field redefinition that maps two different Galileon theories into each other while preserving scattering amplitudes. This duality arises naturally in the context of massive gravity and bigravity theories where the Galileon emerges in the decoupling limit as the helicity zero mode of the massive graviton, with the duality being the decoupling...
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Prof. Fabrizio Canfora (Universidad San Sebastian)01/09/2025, 15:50talk
In the present talk I will describe the first analytic example of a gravitating Skyrmion of unit Baryonic charge in General Relativity minimally coupled to Skyrme model in (3+1) dimensions. I will describe the remarkable properties of this analytic solution and how such gravitating soliton gave rise to the first analytic solutions with non-vanishing Baryonic charge of the Skyrme model on flat...
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Dr Perseas Christodoulidis (Ewha Womans University)01/09/2025, 17:00talk
I will discuss how to construct an EFT that captures non-conservative effects based on recent developments in Schwinger-Keldysh (SK) EFTs. The leading dissipative terms added to the SK action deform the conservation laws in a controlled manner, as demonstrated by two representative examples: Maxwell's theory and general relativity. I will also briefly discuss phenomenological applications in inflation.
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Dr Damianos Iosifidis (Scuola Superiore Meridionale, Napoli)01/09/2025, 17:35talk
I will show how the Belinfante-Rosenfeld improvement terms, that render the energy-momentum tensor symmetric, emerge by coupling the matter to the affine-connection. In this sense the improvement terms correspond to the hypermomentum (microproperties) of matter. I will show how this is realized in two standard examples, the Maxwell field and the Dirac field. I will also show how the...
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Constantinos Skordis (CEICO - FZU and University of Oxford)02/09/2025, 09:00talk
Assuming that gravity on cosmological scales is described by General Relativity (GR), observations indicate that 80% of matter is in the form dark matter. The underlying cosmological model, ΛCDM, provides a superb fit to the data on scales of around 1 Mpc or larger. However, the dark matter particle responsible is so far undetected. Moreover, galactic dynamics display an element of regularity,...
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Prof. Peter Dunsby (University of Cape Town)02/09/2025, 09:50talk
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Charalampos Tzerefos (University of Athens & National Observatory of Athens)02/09/2025, 11:00talk
In the new era of gravitational wave (GW) astronomy, we have access to a new window to investigate cosmology. In this talk, I am going to focus on the so-called scalar induced (stochastic) gravitational waves (SIGW) and how they can act as probes of the early Universe as well as the underlying gravitational theory itself. Specifically, the main results of my PhD thesis will be presented, which...
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Konstantinos Dialektopoulos02/09/2025, 11:35talk
In this talk, I will present a machine learning approach to reconstructing cosmological dynamics using artificial neural networks (ANNs), applied to late-time expansion, structure growth, and scalar-tensor gravity models. This non-parametric method learns directly from observational data—such as cosmic chronometers, BAO, and supernovae—while incorporating realistic uncertainties and...
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Amare Abebe (North-West University)02/09/2025, 12:10talk
I will present some theoretical and observational cosmological constraints on classes of alternative gravitational theories.
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Dr Theodoros Papanikolaou (Scuola Superiore Meridionale)02/09/2025, 12:30talk
In the presence of an active source like primordial magnetic fields (PMFs), the vector perturbations of the metric do not necessarily decay away, but may become significant depending upon the background equation-of-state (EoS) parameter, $w$ for instance during reheating. In this work, we develop a generic formalism for the study of tensor perturbations induced at second order by first-order...
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Mr Lehel Csillag (UBB Cluj, Unitbv Brasov)02/09/2025, 15:00talk
We introduce a novel type of (integrable) vectorial nonmetricity, extending the previous literature by the inclusion of a cubic, completely symmetric term, reminiscent of statistical manifolds. The vectorial degree of freedom and three coefficients completely determine the geometric properties of the proposed connection. We find conditions on these coefficients, which guarantee the...
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Ms Cynthia Belen Arias Pruna (Charles University, Prague)02/09/2025, 15:00talk
We study a class of symmetry operators acting on vector perturbations in the Kerr spacetime and employ them to generate new solutions of Maxwell equations. The operators are second-order in derivatives and are directly constructed from the principal Killing-Yano tensor. One of them reproduces a known result from the Debye potential theory, while the other yields a novel symmetry. When applied...
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Panagiotis Giannadakis (King's College London)02/09/2025, 15:20talk
We investigate the effects of large scalar inhomogeneities during the kination epoch, a period in which the universe’s dynamics are dominated by the kinetic energy of a scalar field, by fully evolving Einstein’s equations using numerical relativity. By tracking the non-linear growth of scalar perturbations with both sub-horizon and super-horizon initial wavelengths, we are able to compare...
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Bertha Cuadros-Melgar (University of Sao Paulo)02/09/2025, 15:20talk
In this work we present a new solution of a black hole surrounded by massive vector fields in the context of Kaluza-Klein theory. This vector field corresponds to a spin-1 graviton that modifies the law of gravity and allows the effects attributed to dark matter in the universe. In order to analyze the influence of the parameters associated to this solution, we perturb the geometry with a...
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Dr Petr Kotlařík (Astronomical Institute, Czech Academy of Sciences)02/09/2025, 15:40talk
When a black hole (BH) rings due to some external perturbation, it emits gravitational waves described by quasi-normal modes (QNMs) – a series of exponentially damped harmonic oscillations. If the Kerr(-Newman) metric fully describes the BH, QNMs carry a unique signature of the BH parameters encoded in the modes' complex frequencies. Consequently, any deviation in the QNMs spectrum from the...
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Prof. Genly Leon (Universidad Catolica del Norte)02/09/2025, 15:40talk
We present a comprehensive dynamical analysis of scalar-field Quintom cosmological models,focusing on scenarios with exponential potentials and both quintessence and phantom compo nents. These models accommodate transitions across the phantom divide (w = −1), permittingrich cosmological behavior including multiple inflationary epochs and bouncing solutions. Em ploying a compact phase-space...
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Despina Totolou (Aristotle University of Thessaloniki & National Observatory of Athens)02/09/2025, 16:00talk
Dark matter remains one of the major open problems in modern cosmology, and PBHs provide a natural and compelling candidate, with the potential to constitute a significant fraction of it. Simultaneously, General Relativity may require modification, particularly in the early universe. In this work, we explore a novel inflationary scenario within Horndeski gravity, focusing on a subclass with a...
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George Cristache (Institute of Space Science- INFLPR subsidiary)02/09/2025, 16:00talk
Gravitational Waves (GW) emission is usually studied within the framework of the Regge-Wheeler-Zerilli equations, which are not exact and often times require numerical integration or extrapolation (a process which involves tuning additional parameters). Our aim is to prescribe a theoretical framework which alleviates some of these technical challenges by employing a Lehmann-Symanzik-Zimmerman...
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Zakaria Belkhadria (Université de Genève / Università di Cagliari)02/09/2025, 16:20talk
We present a model of black hole scalarization where a scalar field couples simultaneously to the Gauss–Bonnet invariant and a U(1) gauge field (can be identified as a dark photon or an electromagnetic field). This combined interaction broadens the conditions for spontaneous scalarization and unify the previous models in one. framework. We track how the electric charge and the two coupling...
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Mr Junkai Wang (Tsinghua University)02/09/2025, 16:20talk
The question "How do we use quantum gravity to understand modern cosmology?" is on the same footing as "How do we use quantum gravity to understand the Standard Model?" The Swampland conjectures distill our lessons about quantum gravity from string theory, the holographic principle, and black-hole physics, imposing powerful constraints on and continually deepen our understanding of low-energy...
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Ifigeneia Klaoudatou (The American College of Greece (Deree))02/09/2025, 17:00talk
We present our work on a class of brane-world models that consist of a flat 3-brane embedded in a five-dimensional bulk space filled with a fluid that satisfies a non-linear equation of state of the form $p=\gamma\rho^{\lambda}$, where $p$ is the ‘pressure’ and $\rho$ is the ‘density’ depending on the fifth space coordinate, and $\gamma$, $\lambda$ are parameters. We show that for $\gamma<0$...
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Mrs Natalia Astudillo (Charles University)02/09/2025, 17:00talk
We derive the explicit form of the Einstein-Gauss-Bonnet field equations for D-dimensional geometries that admit non-twisting, shear-free, and expanding null geodesic congruences, forming thus the famous Robinson-Trautman class of spacetimes, and discuss their structure and particular solutions. In D=4 GR, this class contains Weyl type II spacetimes or algebraically more special solutions such...
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Maria Petronikolou (National Observatory of Athens)02/09/2025, 17:20talk
We explore the potential of f(Q) gravity as an alternative framework to address the $H_0$ and $S_8$ tensions in cosmology. Focusing on three representative f(Q) models, we perform a comprehensive Bayesian analysis using a combination of cosmological observations, including cosmic chronometers, Type Ia supernovae, gamma-ray bursts, baryon acoustic oscillations, and redshift-space...
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Dr Jose Manuel Barrientos Ortiz (Universidad de Tarapacá)02/09/2025, 17:20talk
We construct explicit rotating solutions in Einstein's theory of relativity with a minimally coupled free scalar field rederiving and finding solutions in four or five spacetime dimensions. These spacetimes describe, in particular, the back-reaction of a free scalar field evolving in a Kerr spacetime. Adapting the general integrability result obtained many years ago from Eriş-Gürses to simpler...
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Dr Theodoros Nakas (Institute for Basic Science, CTPU-CGA)02/09/2025, 17:40talk
We present an algorithm to obtain exact black holes endowed with primary scalar hair within the shift-symmetric and $Z_2$-symmetric subclass of beyond Horndeski theories. These solutions depend, in addition to the conventional mass parameter, on a second free parameter encoding primary scalar hair. In the limit of vanishing scalar hair, the solutions smoothly reduce to the Schwarzschild,...
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Andronikos Paliathanasis (Durban University of Technology)02/09/2025, 17:40talk
We review the solution space for the field equations of Einstein's General Relativity for various static, spherically symmetric spacetimes. We consider the vacuum case, represented by the Schwarzschild black hole; the de Sitter-Schwarzschild geometry, which includes a cosmological constant; the Reissner-Nordström geometry, which accounts for the presence of charge. Additionally we consider the...
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Kostas Tzanavaris (Higgs Centre for Theoretical Physics)02/09/2025, 18:00talk
Einstein's equations imply that a gravitationally collapsed object forms an event horizon. But what lies on the other side of this horizon? In this talk, I am going to discuss the results of our new paper (https://arxiv.org/abs/2412.09558 ), presenting an alternative, topologically distinct solution: the Black Mirror. In the black hole solution, the horizon connects the exterior metric to an...
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Prof. Leor Barack (University of Southampton)03/09/2025, 09:00talk
I will review recent work to apply self-force methods to the black-hole scattering problem in the extreme-mass-ratio domain, enabling useful comparisons with similar calculations in post-Minkowskian theory. In particular, I will demonstrate how benchmarking of scattering observables using self-force data can inform efficient resummations of post-Minkowskian formulas that remain accurate even...
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Prof. Nikolaos Stergioulas (Aristotle University of Thessaloniki)03/09/2025, 09:50talk
Machine Learning is finding diverse applications in the field of astrophysics and gravitational wave astronomy. This talk surveys our recent advancements in applying such methodologies. We demonstrate the utility of Deep Residual Networks (ResNets) in discovering new gravitational wave events from binary black hole mergers. Next, we present the calculation of the astrophysical detection...
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Ms Alexandra Eleni Koloniari (Aristotle University of Thessaloniki)03/09/2025, 11:00talk
The detection of gravitational waves has revolutionized our understanding of the universe, offering unprecedented insights into its dynamics. A major goal of gravitational wave data analysis is to speed up the detection and parameter estimation process using machine learning techniques, in light of an anticipated surge in detected events that would render traditional methods impractical. Here,...
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Dr Kyriakos Destounis (Centrer for Astrophysics and Gravitation - Instituto Superior Tecnico)03/09/2025, 11:35talk
Extreme-mass-ratio inspirals (EMRIs) are binary systems composed of a primary supermassive black hole and a secondary compact object of stellar mass. Owing to their significant mass disparity, EMRIs emit gravitational waves in the millihertz frequency band, making them accessible only to future space-based detectors such as LISA. These systems evolve adiabatically, with the secondary...
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Ondřej Zelenka (Astronomical Institute of the Czech Academy of Sciences)03/09/2025, 12:10talk
Conventional searches for gravitational wave signals in detector data are computationally demanding and struggle when certain transient noise sources are present. Recently, machine-learning algorithms have been proposed to address current and future challenges. We present a neural-network based algorithm to search for binary black hole waveforms. We also apply our algorithm to real O3b data...
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Evdokia Chrysovalanti Koursoumpa (Aristotle University of Thessaloniki)03/09/2025, 12:30talk
We used AresGW, a deep residual neural network for gravitational wave detection, to process O3 data from the two LIGO detectors, generating a list of triggers with high significance. To improve the false alarm rate, we also used Gravity Spy, a convolutional neural network designed to identify glitches. We processed ARESGW triggers by removing those that were common between the two networks....
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Sayak Datta (GSSI)03/09/2025, 15:00talk
Asymmetric binaries have attracted increasing attention as golden sources for probing the astrophysical environment in which they evolve. Black holes do not exist in isolation; they inhabit diverse environments where particles and fields, possible of unknown nature, interact with each others and with compact objects. For example, massive BHs are surrounded by accreting matter, dark matter...
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Prof. Diego Rubiera-Garcia (Complutense University of Madrid)03/09/2025, 15:00talk
The recent detections from the EHT Collaboration of the shadows generated by the supermassive objects at the heart of M87 and Milky Way galaxies has prompted a new era in theoretical strong-field astrophysics. In this talk I will discuss the theoretical and basis of this new observational window and its latent power for distinguishing between canonical black holes, regular black holes, and...
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Jann Zosso (Niels Bohr Institute, Center of Gravity)03/09/2025, 15:20talk
The future space-borne gravitational wave observatory LISA may provide the first single event measurement of permanent marks in the fabric of spacetime that remember the passage of a gravitational wave. This effect, known as gravitational memory, is one of the most intriguing predictions of general relativity that has not been observed yet. After offering a particularly illuminating...
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Agustín Silva (Radboud University)03/09/2025, 15:20talk
Extended gravitational models have gained large attention in the last couple of decades. In this talk, I'll examine the solution space of vacuum, static, and spherically symmetric spacetimes within F(R) theories, introducing novel methods that reduce the vacuum equations to a single second-order equation. I'll derive analytic expressions for the metric functions in terms of the arbitrary...
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Angelica Albertini (Charles University, Prague)03/09/2025, 15:40talk
The gravitational waves (GWs) that we have detected so far are emitted by compact binaries where the mass ratio between the two objects is of order 1:1 to 1:10. Third-generation GW detectors will instead allow us to receive different signals, like the ones coming from black hole binaries with a larger mass ratio, from 1:100 up to 1:10^6. The orbits of such systems are expected to be eccentric...
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Alex Giacomini03/09/2025, 15:40talk
New exact pulsed and spinning self-gravitating solutions for the four dimensional SU(2) Einstein-non-linear-sigma model and the Einstein-Skyrme model both minimally coupled to the Maxwell field will be presented. These solutions describe mesonic tubes with finite energy and angular momentum and which are asymptotically gyratons. We show that the found solutions are free of curvature invariants...
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Aravindhan Srinivasan (Charles University, Prague and IM CAS, Prague)03/09/2025, 16:00talk
Almost four decades have passed since the generalization of vacuum Kerr solutions to higher dimensions in the form of Myers–Perry black holes, yet an exact solution generalizing their charged extension (Kerr-Newman) to higher dimensions remains unknown in Einstein-Maxwell theory. In this talk, I will discuss this issue from the viewpoint of the (generalized) Kerr–Schild class. Time permitting,...
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Georgios Loukes-Gerakopoulos (Astronomical Institute, Czech Academy of Sciences)03/09/2025, 16:20talk
This talk concerns the computation of the stochastic gravitational wave (GW) background generated by black hole-black hole (BH-BH) hyperbolic encounters with eccentricities close to one and their comparison with the respective sensitivity curves of planned GW detectors. In this study we took into account hyperbolic encounters that take place in clusters up to redshift 5 and with BH masses...
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Dr Eugeny Babichev (IJCLab)03/09/2025, 16:20talk
I will discuss properties of general stationary and axisymmetric spacetimes, with a particular focus on circularity - an accidental symmetry enjoyed by the Kerr metric, and therefore widely assumed when searching for rotating black hole solutions in alternative theories of gravity as well as when constructing models of Kerr mimickers. It can be shown the local existence of a Kerr-like gauge,...
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Dr Filip Hejda (CENTRA, IST, Lisbon & CEICO, FZU, Prague)03/09/2025, 17:00talk
There has been a surge of interest into collisional Penrose process after Bañados, Silk and West described an idealised edge case, in which particles coming from rest at infinity can collide with arbitrarily high centre-of-mass collision energy close to the horizon of a black hole. However, it turned out that in the vacuum case, there is an unconditional upper bound on the efficiency of...
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Mr Hajime Kobayashi (Yukawa Institute for Theoretical Physics, Kyoto University)03/09/2025, 17:00talk
The tidal response of compact objects reflects the underlying gravitational theory and leaves imprints on the gravitational waveforms emitted during the inspiral phase of binary coalescences. High-precision modeling that includes higher-order post-Newtonian effects is essential to test gravity in a strong regime through constraints on such tidal responses. In this talk, I present a formulation...
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Georgios Kraniotis (University of Ioannina)03/09/2025, 17:20talk
In this work we compute novel analytical expressions for differential curvature invariants for accelerating Kerr-Newman black holes in (anti-)de Sitter spacetime. We explore and prove that some of the calculated frame agnostic scalar polynomial invariants (SPIs), can be used on the detection of horizon and ergosurfaces of this important class of black holes. Using the Bianchi identities we...
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Sayak Datta (GSSI)03/09/2025, 17:20talk
With the observation of the multiple binary inspirals, we begin to question whether the components of the binary are black holes or some exotic compact objects (ECOs). The "black holeness" or the deviation from it can be tested in several ways. The distinguishing feature of a black hole from ECOs in the presence of the horizon. This surface acts as a one-way membrane that absorbs energy. Due...
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Christos Ragiadakos03/09/2025, 17:40talk
Imposing the metric as the fundamental structure of the 4-dimensional spacetime, Einstein derived the gravitational interaction. If instead of the metric we assume as fundamental structure the Frobenius integrable system of geodetic and shear-free Newman-Penrose null tetrad, all the elementary particles and gauge interactions are derived. This fundamental geometric structure is called...
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Prof. Yakov Shnir03/09/2025, 18:00talk
We construct black holes in U(1) gauged scalar theories, minimally coupled to Einstein gravity in asymptotically flat space. Particular examples include non-linear O(3) sigma model, Einstein-Maxwell-Friedberg-Lee-Sirlin type model and in the Einstein-Maxwell-Skyrme theory. We analyze the properties of the hairy black holes and determine their domain of existence. Our discussion focuses mostly...
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Prof. Vladimir Karas (Astronomical Institute, Czech Academy of Sciences)04/09/2025, 09:00talk
Nuclear star clusters (NSCs), found in most galaxies, appear as compact stellar systems located around supermassive black holes (SMBHs) in their centers. They often contain a mix of old and young stars and frequently exhibit signs of recurrent star formation. SMBHs define the loss cone of small angular momentum orbits that plunge to the immediate vicinity of the event horizon, where tidal...
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Prof. Sebastiano Bernuzzi (FSU Jena)04/09/2025, 09:50talk
Binary neutron star mergers (BNSM) are associated with powerful gravitational and electromagnetic astronomical transients. Multimessenger observations of BNSMs promise to deliver unprecedented insights on fundamental physics questions, including constraints on dense matter models and the production of heavy elements. Detailed theoretical predictions of the merger dynamics are crucial for...
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Dr Michalis Agathos (Queen Mary University of London)04/09/2025, 11:00talk
Testing the relativistic strong-field dynamics of general relativity (GR) has been a major motivation in the century-long quest to detect gravitational waves (GWs). Since the first GW detection in 2015, we have been probing the dynamics of gravity and the nature of compact objects, by analysing the observed signals from coalescing black holes and neutron stars. In this talk, I will review the...
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Dr Areti Eleni (University of the Aegean), Prof. Theocharis Apostolatos (National and Kapodistrian University of Athens)04/09/2025, 11:35talk
It has been shown that spherical orbits around Kerr black holes remain
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spherical (zero eccentricity) under the influence of gravitational
radiation reaction in the adiabatic limit. I will show that spherical
orbits in non-Kerr black holes that still preserve most of the good
qualities and symmetries of Kerr spacetime can access certain resonances
in such a way that an initially spherical... -
Andreas Mantziris (University of Coimbra)04/09/2025, 11:55talk
Our latest study (2407.18845) investigates the possibility of generating gravitational waves (GWs) from a curvature-induced phase transition of a non-minimally coupled scalar dark matter field with a Higgs-portal. This analysis is conducted during the transition from inflation to kination for various inflationary scales, considering both positive and negative values of the non-minimal...
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Prasanta Char (Universidad de Salamanca)04/09/2025, 12:15talk
In this work, we perform a Bayesian analysis putting together the available knowledge from the nuclear physics experiments and astrophysical observations to explore the equation of state of supranuclear matter. In particular, we employ a relativistic metamodeling technique to nuclear matter to cover the uncertainties in the parameter space of the saturation properties of nuclear matter, both...
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Mr Grigorios Papigkiotis (Aristotle University of Thessaloniki)04/09/2025, 12:35talk
Neutron stars provide an ideal theoretical framework for exploring fundamental physics when nuclear matter surpasses densities encountered within atomic nuclei. Despite their paramount importance, uncertainties in the equation of state (EoS) have shrouded their internal structure. For rotating neutron stars, the shape of their surface is contingent upon the EoS and the rotational dynamics....
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Ms Claudia Caputo (Charles University, Institute of Theoretical Physics)04/09/2025, 15:00talk
Motivated by the complex phenomena occurring in the vicinity of accreting black holes, this study revisits how additional matter distorts otherwise integrable geodesic motion. Whereas most earlier work considered static, axis-symmetric configurations, real accretion discs rotate and drag the surrounding space-time. To quantify the dynamical impact of this rotation-induced frame-dragging,...
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Prof. Mauricio Valenzuela Uribe (CECs - Universidad San Sebastián)04/09/2025, 15:00talk
This talk explores the overlooked spin-1/2 sector of basic supergravity, challenging the long-standing view—present since the origins of supergravity in the late 1970s—that it is non-physical. We show that this belief arose from assuming the validity of the Dirac conjecture of the theory of constrained Hamiltonian systems. We demonstrate that the conjecture does not hold in this particular...
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Dionysios Kokkinos (Hellenic Mediterranean University)04/09/2025, 15:20talk
Algebraically general solutions in General Relativity are notably rare and less mathematically tractable compared to their algebraically special counterparts. Nevertheless, this kind of solutions is quite interesting in mathematical and physical point of view.
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In a previous study conducted in vacuum with cosmological constant under the framework of Newman-Penrose formalism, we explored an... -
Misbah Shahzadi (Astronomical Institute of Czech Academy of Sciences)04/09/2025, 15:20talk
The worldline of an extended body in curved spacetime can be described by the Mathisson-Papapetrou-Dixon equations when its centroid, i.e., its center of mass, is fixed by a spin supplementary condition (SSC). Different SSC choices result in distinct worldlines. To examine the properties of these choices, we investigate the frequency of circular equatorial orbits of extended bodies within the...
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Dr Marcelo Rubio (Gran Sasso Science Institute (GSSI))04/09/2025, 15:40talk
I will discuss the Cauchy problem of self-interacting massive vector fields, and explain why they often face instabilities and apparent pathologies. After showing that these issues are due to the breakdown of the well-posedness of the corresponding initial-value problem, I will characterize the well-posedness breakdowns and explicity show that they can be avoided by fixing the equations in a...
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Aaron Held (École Normale Supérieure)04/09/2025, 15:40talk
I will clarify that higher-derivative theories and associated opposite-sign kinetic terms are no obstruction for long-lived classical motion. For point-particle models, integrability allows for proof of global stability. For scalar field theories, mathematical theorems establish well-posed time evolution for sufficiently small, compactly-supported initial data and numerical scattering...
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Dr Charalampos Markakis (Stony Brook University & University of Illinois)04/09/2025, 16:05talk
We explore symmetric and discontinuous integrators for solving partial differential equations (PDEs) over long periods. Explicit solvers are Courant-limited and fail to preserve Noether symmetries, impacting their effectiveness in long-time integration scenarios. We thus explore symmetric (exponential, Padé, or Hermite) integrators, which are unconditionally stable and known to preserve...
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THEOCHARIS APOSTOLATOS (National and Kapodistrian University of Athens)04/09/2025, 16:40
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Paraskevas Lampropoulos (University of Amsterdam/Astroparticule et Cosmologie, CNRS, Université Paris Cité)poster
Merging massive black hole binaries (MBHBs) are important gravitational wave (GW) sources for the future space-based observatory LISA. The GW signal from the merger will be detected throughout the entire Universe. Characterization of the GW signal allows us to infer masses and spins of MBHs, the position of the source in the sky and the distance. This information will allow us to understand...
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Dr Simran Arora (YITP, Kyoto University, Japan)talk
We study the dynamics of the interacting models between the Gauss-Bonnet (GB) coupled scalar field and the dark matter fluid in a homogeneous and isotropic background. A key feature of GB coupling models is the varying speed of gravitational waves (GWs). We utilize recent constraints on the GW speed and conduct our analysis in two primary scenarios: model-dependent and model-independent. In...
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Dr Damianos Iosifidis (Scuola Superiore Meridionale, Napoli)talk
We derive the equations of motion of a test particle with intrinsic hypermomentum in spacetimes with both torsion S and nonmetricity Q (along with curvature R). Accordingly, S and Q can be measured by tracing out the trajectory followed by a hypermomentum-charged test particle in such a non-Riemannian background. The test particle is approximated by means of a Dirac δ-function. Thus we find a...
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Dr Michalis Agathostalk
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Alexandra Eleni Koloniari (Aristotle University of Thessaloniki)poster
The detection of gravitational waves (GWs) from compact binary mergers has transformed astrophysics and pushed the development of more efficient search methods. While matched-filtering remains the standard, the growing data volumes from LIGO, Virgo, and KAGRA have spurred interest in machine learning (ML) for its scalability. This work evaluates the sensitivity of AresGW model 1, an ML-based...
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