Troisième Assemblée Générale du GdR Ondes Gravitationnelles

14 oct. 2020, 09:00 → 15 oct. 2020, 19:00 Europe/Paris

En ligne

Le GdR Ondes Gravitationnelles (http://gdrgw.in2p3.fr/) a été crée en 2017 avec le but de rassembler la communauté scientifique intéressée par l’exploration de l’Univers avec les ondes gravitationnelles, et de lui fournir des occasions de rencontres et de discussions communes. 

La troisième assemblée générale du GdR Ondes Gravitationnelles se tiendra en ligne, et couvrira les thèmes d’intérêt du GdR, représentés par ses Groupes de Travail. Les instructions de connexion seront transmises à la liste des participants après la date d'échéance des inscriptions. 

L'inscription à cette réunion est obligatoire avant le 30 septembre 2020. Il faut, au préalable, devenir membre du GdR en s'inscrivant sur le site http://gdrgw.in2p3.fr/

La date limite pour envoyer une contribution est le 29 août 2020.

        

 

 

 

 

 

mercredi 14 octobre

10:15 → 10:30 Bienvenue

10:30 → 11:30 Séminaires sur invitation

10:30 Présentation des résultats de O3

Orateur: Benoit Mours (IPHC Strasbourg)

GDR-OG-O3.pdf

11:00 Implications astrophysiques des résultats de O3

Orateur: Dr Tito Dal Canton (NASA GSFC)

gdr_og_20201014.pdf

11:30 → 12:00 pause café

12:00 → 13:00 Séminaires sur invitation

12:00 La mesure de H0

Orateur: Mickael Rigault (LPC)

gdr_gw_oct2020.pdf

12:30 25 years of European Pulsar Timing Array

Orateur: Siyuan Chen

syuan_chen_gdr_epta_chen.pdf

13:00 → 14:00 Déjeuner au buffet

14:00 → 15:00 Séminaires sur invitation

14:00 L'équation d'état des étoiles à neutrons

Orateur: Francesca Gulminelli (LPC/Ensicaen)

Gulminelli_GDR_OG.pdf

14:30 La science future avec les ondes gravitationnelles

Orateur: Nelson Christensen (Artemis, Observatoire de la Cote Azur)

GDR_2020_NC.pdf

15:00 → 15:30 Discussion sur la science future des OG et sur la prospective in2p3

15:30 → 16:00 pause café

16:00 → 17:15 Groupes de travail: Population des sources, Etoiles à neutrons, supernovae et synthèse des éléments lourds, Prédiction et suivi des signaux multi-messager

16:00 ENGRAVE: O3, O4 and the GAP

I will present the activity of the ENGRAVE collaboration during the LV O3 run, the science case for the gap between the O3 and O4 runs and the perspectives on the organization of the collaboration for the O4 run.

Orateur: Susanna Vergani (CNRS - Paris Observatory)

Susanna_Vergani_GDRGW20.pdf

16:15 Fink, a new generation broker for the LSST community

Next generation experiments such as the Vera Rubin Observatory Legacy Survey of Space and Time (LSST) will provide an unprecedented volume of time-domain data opening a new era of optical big data in astronomy. To fully harness the power of these surveys, new methods must be developed to deal with large data volumes and to coordinate resources for follow-up of promising candidates.
In this talk I will present Fink, a broker developed to face these challenges. Fink is based on high-end technology and designed for fast and efficient analysis of big data streams. I will present its traditional broker features and highlight the state-of-the-art machine learning techniques used to generate classification scores for a variety of time-domain phenomena: supernovae, microlensing events, solar system objects and anomalies as well as the exploration of the multi-messenger astronomy sector (gamma ray bursts, neutrinos, gravitational waves). I will detail the first results obtained by the Fink collaboration on selected science cases using the ZTF alert stream data between 2019 and 2020, and highlight the challenges towards the processing of LSST alert data.

Orateur: Dr Julien Peloton (CNRS-IJCLab)

Fink_GDR_OG.pdf

16:30 3U Transat : constellation de nano-satellites pour observer le ciel transitoire

L'essor de l'astronomie multi-messager et du ciel transitoire nécessite des moyens d'observations à haute énergie couvrant tout le ciel afin de permettre la meilleure synergie avec les détecteurs d'ondes gravitationnelles et de neutrinos. Le recours à une constellation de nano-satellites pour détecter des transitoires à haute énergie et notamment des sursauts gamma est une solution innovante et dans l'air du temps. Je présenterai le projet 3U Transat initié à l'IRAP & ses exigences scientifiques et techniques. Je vous montrerai quelques exemples de constellations possibles que nous avons étudiées ainsi que les performances attendues. Le projet 3U Transat suit actuellement une phase 0 avec l'aide du CNES.

Orateur: Dr Olivier GODET (IRAP)

2020-10-14_3Utransat_GODET.pdf

16:45 Progenitors of low-mass binary black-hole mergers in the isolated binary evolution scenario

The formation history, progenitor properties and expected rates of the binary black holes discovered by the LIGO-Virgo collaboration, through the gravitational-wave emission during their coalescence, are now a topic of active research. We aimed at studying the progenitor properties and expected rates of the two lowest-mass binary black hole mergers, GW151226 and GW170608, detected within the first two Advanced LIGO-Virgo observing runs, in the context of the classical isolated binary evolution scenario.
We used the publicly-available 1D-hydrodynamic stellar-evolution code MESA, which we adapted to include the black-hole formation and the unstable mass transfer developed during the so-called common-envelope phase. Using more than 50 000 binary simulations, we explore a wide parameter space for initial stellar masses, separations, metallicities and mass-transfer e?ficiencies. We obtained the expected distributions for the chirp mass, mass ratio and merger time delay by accounting for the initial stellar binary distributions. We predicted the expected merger rates that we compare with the detected gravitational-wave events, and studied the dependence of our predictions with respect to (yet) unconstrained parameters inherent to binary stellar evolution.
Our simulations for both events show that, while the progenitors we obtain are compatible over the entire range of explored metallicities, they show a strong dependence on the initial masses of the stars, according to stellar winds. All the progenitors found follow a similar evolutionary path, starting from binaries with initial separations in the 30-200 Rsun? range, experiencing a stable mass
transfer interaction before the formation of the first black hole, and a second unstable mass-transfer episode leading to a common-envelope ejection that occurs when the secondary star crosses the Hertzsprung gap. The common-envelope phase plays a fundamental role in the considered low-mass range: only progenitors experiencing such an unstable mass-transfer phase are able to merge in less
than a Hubble time. We find that all the integrated merger rate densities are below 0.5/yr/Gpc$^3$ in the local Universe, the highest rate density being compatible with the observed rates. The common-envelope e?ficiency ?CE has a strong impact on the progenitor populations. A high-e?ciency scenario with ?CE = 2.0 is favored when comparing the expected rates with observations.

Orateur: Prof. Sylvain Chaty (Université Paris Diderot, CEA Saclay)

2020-10-14-AG-GdR-GW-SChaty-low-mass-BBH.pdf

17:00 Did binary neutron star mergers produce all the r-process elements in the Universe ?

The main origin of r-process elements is currently a subject of debate, the candidates being binary neutron star mergers and rare supernovae. While the discovery of GW170817 and the associated kilonova has provided strong support to the former hypothesis, detailed comparison of the predictions of galaxy evolution models with the observed r-process abundances reveal important discrepancies both in low- and high-metallicity environments. In this talk I will show that these discrepancies can be alleviated by including more realistic physical effects, such as a detailed description of the binary neutron star merger rates in low-mass galaxies and turbulent mixing of the freshly synthesized elements in the interstellar medium. These results show that merging binary neutron stars are likely the dominant source of r-process elements.

Orateur: Irina Dvorkin (Institut d'Astrophysique de Paris)

gdr-10-20.pdf

jeudi 15 octobre

10:00 → 10:45 Groupe de travail: Développement des détecteurs

10:00 Scattered light subtraction and GW detector calibration

Scattered light has limited at times all interferometric gravitational wave (GW) detectors to date. We describe how some of the scattered light noise contribution have been subtracted from strain data of Advanced Virgo during O3. We model in detail the scattered light coupling from suspended end benches and show how further noise subtraction can be achieved. The fitted model parameters can be used to characterize the interferometer optical properties. In particular it provides a new method to calibrate GW detectors that is fully independent from previously used methods (free swinging Michelson fringes, photon calibration and Newtonian calibration).

Orateur: Michal Was (LAPP)

GDROG_2020-10_scatter.pdf

10:15 Reducing quantum noise for Advanced Virgo gravitational-wave detector by using frequency-dependent squeezing technique with Einstein-Podolsky-Rosen (EPR) entanglement

In order to increase the science reach of GW detectors, it is fundamental to reduce the quantum noise, composed of radiation pressure noise (RPN) at low frequencies (roughly < 100 Hz) and shot noise (SN) at high frequencies (roughly > 100 Hz). Since the quantum noise is generated by vacuum fluctuations entering the interferometer, the injection of phase-squeezed vacuum states reduces the SN and increases the RPN. Frequency-independent squeezing (FIS) has been implemented in the Advanced Virgo for the current LIGO-Virgo observation run O3. As RPN does not limit the current sensitivity of Advanced Virgo, the increasing of RPN due to FIS is not a problem. However, for the next detector upgrade (Advanced Virgo+), RPN will limit the sensitivity at low frequencies. In order to reduce simultaneously SN and RPN, the injection of frequency-dependent squeezing (FDS) is needed. This can be obtained inserting an external filter cavity between the squeezing source and the interferometer, before the injection of the squeezed vacuum in the interferometer. Alternatively, it has been recently proposed that a broadband reduction of quantum noise in gravitational-wave detectors can also be achieved using a pair of squeezed EPR-entangled beams. A frequency-dependent optimization of the injected squeezed light fields is possible with this technique, without the need of an external filter cavity. After an introduction about the squeezing techniques in the context of GW detectors, we will introduce the EPR squeezing and we will describe the R&D on-going effort in Virgo about this technique. In particular, we will present the development of a key component, an etalon, designed and tested to be used as an optical resonator for the EPR squeezing experiment.

Orateur: Catherine Nguyen

GdrOG_15102020_Squeezing_Nguyen.pdf

10:30 Noise propagation through TDI for the noise budget of LISA mission

Gravitational waves (GWs) are opening a new window to investigate our Universe. As an effort to broaden the frequency band of GW observation, LISA will be the first-ever spaceborne GW detector, aiming to detect the GW signals from various astrophysical and cosmological sources in the frequency band from 0.1 mHz to 1 Hz. To study the noises and how to reduce them at the required levels allowing observation of GW, a performance model and an instrument simulator have been developed by the LISA Consortium, in particular the Performance and the Simulation working groups. The understanding of the sources and their propagation are ones of the key elements in the current phase A of the LISA mission. The noise budget will take into account all the noises currently known as well as the propagation of these noises through data processing methods. This talk is aiming to give an overview of how we model the noises from the LISA instrument to the interferometer measurements and calculate the noise propagation through the Time Delay Interferometry (TDI) algorithm to obtain the noise budget. First, we will give a brief introduction about TDI - the method to suppress laser noise, jitter noise, clock noise - as well as the up-to-date beam model for the interferometer measurements we use for the study. Then, the calculation of transfer functions for some noises after TDI processing will be presented. The comparison between the analytic and simulation data from LISANode will also be shown to consolidate our results. These transfer functions then are the input for the Performance working group to study the noise budget for the LISA mission.

Orateur: M. Quang Nam Dam (APC - Université de Paris)

Nam-presentation-3rd-GdR-meeting.pdf

10:45 → 11:15 Groupe de travail: Méthodes d'analyse des données

10:45 A Statistical Inference Approach to Space-Based Interferometry

One of the main challenges of space-based interferometry for gravitational-wave detection is the cancellation of laser frequency noise, whose power culminates eight orders of magnitude above the gravitational-wave signal. The standard technique to remove this noise is time-delay interferometry (TDI), a set of linear combinations of delayed phasemeter measurements tailored to cancel noise terms. We examine TDI from a statistical inference standpoint, constructing a model likelihood that directly depends on single-link measurements and accounts for their correlations. Based on previous works demonstrating the relationship between TDI and principal component analysis, we build a compact framework for space-based gravitational-wave data analysis that minimizes the measurement variance. As an application, we show that it provides a compelling description of the LISA data analysis problem by demonstrating our ability to fit for inter-spacecraft light travel times, source parameters, and noise covariance components simultaneously.

Orateur: Quentin Baghi (NASA GSFC - USRA)

2020-10-qbaghi-gdr_iii_v1.pdf

11:00 First level characterisation the stochastic foreground signal of the LISA mission

The ESA LISA mission, is going to fly in the early 2030s, and it is going to be the first Gravitational Wave observatory in space. In contrast to the present ground based detectors, LISA is going to be a signal-dominated laboratory. This means that we expect that the data-stream will be populated with gravitational wave signals overlapping in time, and in frequency. In addition, different astrophysical population models, predict a type of signal that would generate a confusion foreground noise. In this work, we present a generic method which aims to characterise the foreground signals originating from different types of sources. Assuming idealised detector conditions, we apply an iterative procedure which allows us to predict the different levels of foreground noise, after subtracting the sources with higher SNR than a given threshold.

Orateurs: Dr Nikolaos Karnesis (APC Paris), Stanislav Babak (APC)

20201014_Gdr_karnesis.pdf

11:15 → 11:45 pause café

11:45 → 12:45 Groupe de travail: Méthodes d'analyse des données

11:45 Parameter estimation and sky localization of massive binary black holes with LISA

LISA is a future space-based gravitational wave detector that will complement the LIGO/Virgo observations at much lower frequencies, enabling the detection (among other targets) of coalescences of massive black hole binaries (MBHB). Most MBHB signals are expected to be short and merger-dominated. The development of data analysis tools for LISA is still in its exploratory phase, and it is crucial to understand the capabilities of LISA and the trade-offs in its instrumental design. While previous studies often used simplified signals and instrument response and a Fisher matrix approach, we developed a set of tools that allows fast likelihood computations for Fourier-domain waveform models, enabling Bayesian analyses exploring the full parameter space. We present examples of simulated parameter recovery for massive black hole binaries. We highlight degeneracies in parameter space, finding that both frequency-dependent effects in the instrument response and higher harmonics in the signal play a crucial role in breaking these degeneracies and refining the sky localization of the source. We also discuss whether LISA is able to detect and localize these systems before the merger occurs, enabling advance warnings for EM observatories.

Orateur: Dr Sylvain Marsat (APC)

gdr_marsat_2020-10-15.pdf

12:00 95% upper limit on strain amplitude for Continuous Gravitational Wave signal using Pulsar Timing Array

The Pulsar Timing Array (PTA) collaboration aims to detect low frequency gravitational wave signals using high precision timing observations of millisecond pulsars. The international collaboration combines data from several radio telescopes distributed throughout the world to enhance detection sensitivity. The data analysis pipelines are usually computationally expensive because of complex models and large amount of data. Here we will present how it is possible to speed up computation by first ranking the pulsars by their signal to noise ratio with respect to a continuous gravitational wave (CW) signal and keeping a subset of the best pulsars. We will then show preliminary results for sensitivity curves and 95% upper limit plots on the amplitude of CW signal.

Orateur: Mikel Falxa

Mikel_falxa_GdR talk.pdf

12:15 Impact of solar-system ephemeris imperfections on Pulsar Timing Arrays results using INPOP data

Pulsar Timing Array (PTA) projects aim at detecting a very low-frequency gravitational wave stochastic background (GWB) by probing its imprints in times of arrival (ToAs) of radio signals from pulsars. The expected signature is characterized by a quadrupolar angular correlation between positions of pulsars in the sky. The pulsar timing data reduction involves a transformation of geocentric ToAs to the quasi-inertial solar system barycenter (SSB) frame. PTAs sensitivity to the GWB requires to take into account a possible statistical and systematic errors in the SSB position derived from the planetary ephemeris solutions. If those errors are present and ignored, they produce a signal with a dipolar angular correlation that could "leak" into the GWB measurement. I will present the current status of my work (in collaboration with the group from GEOAZUR/IMCCE) on optimization of the search for a GW stochastic background accounting for planetary ephemeris uncertainties using INPOP (Intégrateur Numérique Planétaire de l'Observatoire de Paris) data.

Orateur: M. Aurélien Chalumeau (APC/USN)

Presentation_achalumeau_Telecon_GdR_201015.pdf

12:30 Sparse data inpainting for the recovery of gapped gravitational waves signals

The detection of galactic binaries as sources of gravitational waves promises an unprecedented wealth of information about these systems, but also raises several challenges in signal processing. In particular, the variety of sources and the presence of both planned and unplanned gaps call for the development of robust methods. We describe here an original non-parametric reconstruction of the imprint of galactic binaries in measurements affected by instrumental noise and data gaps both typical of the space-based gravitational wave observatory LISA. We carefully show that a sparse data representation gives a reliable access to the physical content of the interferometric measurement, even when the data is gapped. In particular we check the successful extraction of the gravitational wave signal on a simple yet realistic example involving verification galactic binaries recently proposed in LISA data challenges.

Orateur: Dr Hervé Moutarde (Irfu, CEA)

moutarde-gdr-og-2020-10-15.pdf

12:45 → 14:00 Déjeuner au buffet

14:00 → 14:45 Groupe de travail: Cosmologie

14:00 Solving the Hubble tension with gravitational-wave standard sirens and electromagnetic counterparts

Compact object mergers offer a new and independent means of measuring the Hubble constant by combining the source’s distance derived from the gravitational wave form with its redshift obtained from electromagnetic follow-up. It is expected that with a few tens of events, this multi-messenger method could reach a precision fit to resolve the pending tension between early- and late-Universe measurements of the Hubble constant. However, this method is limited by intrinsic degeneracies in the gravitational wave signal, especially between the system’s distance and its orbital inclination. Fortunately, these degeneracies can be partially lifted by considering the merger’s electromagnetic counterparts, which can independently constrain the inclination angle. This was done with the historic event GW170817, where the afterglow counterpart enabled a great improvement in the estimate of the inclination angle. Access to such counterparts is not guaranteed for all events because they are faint for distant or very inclined systems. We present models for emission and detection of multi-messenger radiation from binary neutron star mergers, as well as population models for these sources. Using these models, we quantify the benefit of including the inclination angle information from electromagnetic counterparts in obtaining a precise measurement of the Hubble constant. Though the information brought by the counterparts greatly improves the measurement for individual events, we find that the rareness of the electromagnetic counterparts disallows them to significantly contribute to the measurement of the Hubble constant in the long term, at least for the design-level LIGO-Virgo gravitational interferometers. We discuss these results under different source population hypotheses.

Orateur: Raphaël Duque (Institut d'Astrophysique de Paris)

duque_jeudi_14h.pdf

14:15 PBHs and SBGWs from multi-fields dynamics during inflation

We have recently proposed a new model-independent mechanism for producing primordial black holes from a period of multi-field inflation. The desired enhancement of primordial fluctuations at short scales naturally occurs when the inflationary trajectory exhibits a strong turn, that is a limited period during which the trajectory strongly deviates from a geodesic in field space. The mechanism, independently of being able to account for all or a fraction of dark matter in the form of primordial black holes, has the potential of exhibiting unique features accessible to observation through a stochastic background of gravitational waves. The peculiar features in the induced gravitational waves spectrum, such as characteristic peaks and oscillating patterns, offers the possibility to link the microscopic dynamics of inflation with the gravitational waves energy density potentially detectable by LISA.

Orateur: Dr Jacopo Fumagalli (IAP)

Fumagalli_GdRb.pdf

14:30 Cordes cosmiques, ondes gravitationnelles et abondance des vortons

Les cordes cosmiques sont des défauts topologiques unidimensionnels formés à la suite d'une brisure spontanée de symétrie. Si des cordes cosmiques ont été formées dans l'Univers primordial, elles peuvent être à l'origine d'un fond stochastique d'ondes gravitationnelles détectable dans une large bande de fréquence. La détection d'un tel signal permettrait de contraindre les extensions du modèle standard des particules à très haute énergie.
Dans cette présentation, nous souhaiterions traiter étudier le cas de cordes supraconductrices. Sous certaines hypothèses, le courant qui parcourt la corde peut être suffisant pour la maintenir dans un état stable et prévenir l'émission d'ondes gravitationnelles. Ces configurations stables circulaires sont appelés des vortons. Nous proposons de quantifier cet effet sur le fond stochastique et nous montrons que l'abondance de matière noire permet de contraindre de tels modèles.

Orateur: Pierre Auclair (Laboratoire APC)

seminar.pdf

14:45 → 15:15 Groupe de travail: Formes d'onde

14:45 Towards the gravitational wave phase of compact binaries with 4PN precision

The precise knowledge of the gravitational phase of compact binaries is crucial to the detection methods for gravitational waves. To this days, we know it analytically (for non-spinning systems) up to the 3.5 post-Newtonian (PN) order, ie. up to the (v/c)^7 correction beyond the leading order. If this precision is sufficient for the data analysis of the current generation of detectors, the next one (notably LISA) will require at least a 4.5PN accuracy.

An essential ingredient to compute the gravitational wave phase is the mass quadrupole moment, that we are currently computing for compact binaries at 4PN order, using a post-Newtonian-multipolar-post-Minkowskian matching algorithm. This method involves challenging technical issues, due to the appearance of non-physical divergences, that have to be properly regularized, as well as non-linear interaction terms (dubbed "tails"). In this talk, I will present the current status of the computation, and review the steps that are left in order to fully derive the gravitational phase at 4PN order.

Orateur: François Larrouturou (IAP)

presentation_Larrouturou.pdf

15:00 Tidal effects in the gravitational-wave phase of compact binaries

We compute the gravitational-wave (GW) energy flux up to the next-to-next-to-leading (NNL) order of tidal effects in a spinless compact binary system on quasi-circular orbits. Starting from an effective matter action, we obtain the stress-energy tensor of the system, which we use in a GW generation formalism based on multipolar-post-Minkowskian (MPM) and post-Newtonian (PN) approximations. The tidal contributions to the multipole moments of the system are first obtained, from which we deduce the instantaneous GW energy flux to NNL order (formally 7PN order). We also include the remaining tidal contributions of GW tails to the leading (formally 6.5PN) and NL (7.5PN) orders. Combining it with our previous work on the conservative equations of motion (EoM) and associated energy, we get the GW phase and frequency evolution through the flux-balance equation to the same NNL order. These results extend and complete several preceding results in the literature.

Orateur: Quentin Henry (Institut d'Astrophysique de Paris)

Quentin_Henry_GdR.pdf

15:15 → 15:45 pause café

15:45 → 16:45 Groupe de travail: tests de la relativité générale et théories alternatives

15:45 Tests of general relativity and cosmology with gravitational from binary neutron stars

Since the detection of the binary neutron star merger GW170817, gravitational waves (GWs) are rapidly entering in the field of cosmology. In this talk I will discuss how GWs can be used to probe deviations from General Relativity (GR) on cosmological scales. In particular I will focus on a modified GW friction term and a modified dispersion relation, while at the same time leaving the Hubble constant as a free parameter. Using a statistical method able to combine measurements of GWs as well as their electromagnetic counterpart and hosting galaxy, I will present novel constraints on the Hubble constant and the GW friction and dispersion terms. I will show that it is fundamental to consider jointly the measurements of these 3 parameters in order to avoid a biased measurement of one of the three. Finally I will present the results from GW170817, leading to updated and tighter upper-limits on GR modifications.

Orateur: Dr Simone Mastrogiovanni (Astroparticule et cosmologie, Paris Diderot university)

cosmo_test_GR_2020.pdf

16:00 Testing spacetime birefringence with gravitational waves

The direct detection of gravitational waves in 2015 offered a new probe of the structure of spacetime. The study of the propagation of the gravitational waves from the coalescence of binary systems of black holes detected by LIGO and Virgo already enabled to constrain the dispersive nature of gravitational waves. This talk presents the current work towards probing the birefringent nature of spacetime. The deviation in the propagation of the gravitational wave is derived in the Standard Model Extension framework, where the new corresponding term corresponds to a mass dimension operator of 5 and induces a violation of Lorentz invariance. The deformation is implemented in the gravitational waves templates used by LIGO and Virgo in order to provide a measurement of the components of the deformation tensor with the available detections.

Orateur: Leïla Haegel (Laboratoire APC, Université Paris-Diderot / CNRS)

2020-10-15_gdr_og_tgr_birefringence.pdf

16:15 Black Holes Lessons from Multipole Ratios: A New Window into Black Holes

We compute gravitational mass and angular momentum multipole moments for four-dimensional black holes and fuzzball geometries thereof. For Kerr and for supersymmetric black holes many multipole moments vanish, but we show that an infinite number of ratios of vanishing multipoles are constant. We calculate these ratios for the first time, using two very different methods; the results agree spectacularly for certain black holes. Hence our work establishes that ratios of vanishing multipoles are intrinsic properties of four-dimensional black holes. For the Kerr black hole these ratios pose strong constraints on the parameterization of possible deviations from the Kerr geometry that should be tested by future gravitational wave interferometers.

Orateur: Daniel Mayerson (IPhT, CEA Saclay)

presentation_Mayerson_multipoles.pdf

16:30 Tidal Love Numbers of Microstate Geometries

Black-hole microstate (fuzzball) geometries are the only explicit top-down constructions of structure at the scale of the horizon, which is needed to solve the Information Paradox. We compute for the first time the Tidal Love Numbers of certain microstate geometries, and compare them to those of the corresponding black hole. We also discuss the implications for the physics of the structure at the horizon that may be posed by the bounds on Tidal Love Numbers from EMRI gravitational waves.

Orateurs: Iosif Bena (IPhT, CEA-Saclay), Dr Pierre Heidmann (John Hopkins University)

GDR-2020-Love-numbers-BENA.key

16:45 → 17:00 Discussion de clôture