Program

8:30

Registration

8:50

Opening welcome

9:00-9:30

Schutz

Levan

García-Bellido

9:30-10:00

10:00-10:30

Husa

Zilhao

Palenzuela

10:30-11:00

11:00-11:30

Casanueva

Pannarale

Glampedakis

11:30-12:00

Oltean

12:00-12:30

Dovale

Davies

Wang

12:30-13:00

García Quirós

Veitch

Ramos Buades

13:00-14:30

14:30-15:00

Sorazu

Di Palma

Nesseris

15:00-15:30

Wachter

15:30-16:00

Mir

Tenorio

Franchini

16:00-16:30

16:30-17:00

Esteban

Menéndez

17:00-17:30

Rivas

Torres-Forné

17:30-18:00

Estellés

Sanchís-Gual

19:30-20:30

B. Schutz ( public lecture )

20:30

Banquet

Name

Title/Abstract

Davies, Gareth

Extending the PyCBC search to a global detector network. The worldwide gravitational-wave interferometer network currently consists of the two LIGO observatories in the United States and the Virgo observatory in Italy. With the start of the third advanced LIGO observing run, O3, the three-detector operation will be the norm, and later on, more detectors will be added with the addition of KAGRA, and then LIGO-India over the next few years. Searches for compact binary coalescence signals coincident between detectors have previously been developed for use in a two-detector network, with data from the third detector (if present) being used in follow-up procedures. The search pipelines must therefore be altered to include the extra information from these additional detectors. We present the work performed to extend the PyCBC offline coincident search to use three detectors, development of a new ranking statistic, and of other general pipeline improvements since O2, and how show how these changes improve our sensitivity to CBC sources.

Di Palma, Irene

A nonlinear analysis of Gravitational Waves from Core-collapse Supernovae Core collapse supernovae, among the most energetic explosions in the modern Universe, have not been detected yet, while gravitational waves have been detected from mergers of binary black holes and binary neutron stars. To enhance the detection efficiency of such category of signals we present a nonlinear method based on convolutional neural network algorithm to extract core collapse supernova signals embedded in Gaussian noise with spectral behaviour of Advanced LIGO and Virgo detectors.
Using this new approach we can classify signal from noise and identify the signal more efficiently than the algorithm currently used by the LIGO-Virgo Collaboration to search for gravitational wave transient signals.

Dovale, Miguel

Interaction of light and mirrors: challenges, tools and solutions. Gravitational-wave detection is perhaps the most demanding application within the field of precision measurement. LIGO, the most sensitive length-sensing device ever built, features two 4 km-long optical resonators whose mirrors serve as test masses for measuring ripples through spacetime. The laser beam inside the resonator measures the distance between the mirrors continuously with an unprecedented precision of better than 10^(-18) meters (more than 10,000 times smaller than a single atom in the surface of the mirror). The optomechanical interaction between the high-power optical field and the imperfect test masses, however, imposes fundamental limits to this measurement: coating thermal noise, radiation pressure effects, and parametric instabilities, are some of the most important technical challenges being faced by the detectors. In this talk I discuss the work and the tools being developed to address these issues, leading the way to a new generation of detectors with ten times better sensitivity.

Esteban Delgado, Juan José

Toward a Space-based Gravitational Wave Observatory. In September 2015, the LIGO observatories detected the first direct observation of gravitational waves, opening the window to a new era for astronomy. On 3 December 2015, the European Space Agency (ESA) launched LISA Pathfinder (LPF), a single satellite technology demonstrator for the space-based gravitational wave observatory LISA. On 22 May 2018, NASA and German Research Centre for Geosciences (GFZ) launched GRACE Follow-on mission (GFO), a twin satellite constellation in formation flying. GFO has successfully proved that technologies for a LISA-like inter-S/C optical links are ready. The LISA project has been accepted by ESA for the L3 mission slot and scheduled to be launched in 2034. In this presentation, we will focus on the instruments onboard LPF and GFO and the way toward LISA.

Estellés Estrella, Héctor

A time domain phenomenological model for gravitational waves from binary black hole coalescence. Accurate and fast models for gravitational wave signals are required for confident extraction of physical information about the sources of gravitational wave observations, with more stringent requirements needed as the sensitivity of gravitational wave observatories becomes better. Phenomenological waveform models in the frequency domain have become a standard tool of gravitational wave data analysis, providing a number of valuable features: fast and closed-form implementations that provide insight about waveform phenomenology, modularity to treat independently different aspects of the morphology of CBC signals: spins effects, higher order modes, precession, or eccentricity. However, the frequency domain nature of current phenomenological models can obscure and mix effects that otherwise could be cleaner in time domain, e.g. they make it difficult to cleanly separate the merger and ringdown, which complicates applications to tests of general relativity. Here we present a highly accurate and computationally efficient phenomenological model in the time domain for the dominant mode of spin-aligned systems and the details of its construction and validation. By working in the time domain, the model allows for a cleaner separation of merger and ringdown part of the waveform, and gives rise to new parameterisations of deviations from general relativity, and we discuss how these features benefit tests of general relativity. In addition we discuss how this new approach will benefit the construction of phenomenological models for precessing or eccentric signals, and subdominant spherical harmonics.

Franchini, Nicola

Spontaneous scalarization in Horndeski gravity. Spontaneous scalarization is a mechanism that endows relativistic stars and black holes with a nontrivial con guration only when their spacetime curvature exceeds some threshold. The standard way to trigger spontaneous scalarization is via a tachyonic instability at the linear level, which is eventually quenched due to the effect of non-linear terms. I will identify all of the terms in the Horndeski action that contribute to the (effective) mass term in the linearized equations and, hence, can cause or contribute to the tachyonic instability that triggers scalarization..

García-Bellido, Juan

Gravitational Wave signatures of Primordial Black Holes as Dark Matter. More than twenty-two years ago, we predicted that massive primordial black holes (PBH) would form via the gravitational collapse of radiation and matter associated with high peaks in the spectrum of curvature fluctuations, and that they could constitute all of the dark matter today. In 2015, we predicted the clustering and broad mass distribution of PBH, which peaks at several Msun, and whose high-mass tails could be responsible for the seeds of all galaxies. Since then, LIGO has detected gravitational waves from at least twenty merger events of very massive black hole binaries. We propose that they are PBH, and predict that within a few years a less than one solar mass PBH will be detected by AdvLIGO-VIRGO, and that in 10 years, an array of GW detectors (i.e. LIGO, VIRGO, KAGRA, INDIGO, etc.) could be used to determine the mass and spin distribution of PBH dark matter with 10% accuracy. Thus, gravitational wave astronomy could be responsible for a new paradigm shift in the understanding of the nature of dark matter and structure formation.

García Quirós, Cecilio

PhenomXHM - a modular, accurate and computationally efficient waveform model including subdominant spherical harmonics and mode mixing effects. We present PhenomXHM, a model for subdominant spherical harmonics of coalescing binary black hole systems, which is calibrated to non-precessing numerical relativity simulations and extreme mass ratio waveforms. The model is based on the new PhenomX model, which is calibrated to the dominant quadrupole mode for non-precessing systems, and supersedes the PhenomD and PhenomP models, which have become standard tools in gravitational wave data analysis. PhenomXHM currently includes four harmonics in addition to the dominant quadrupole mode, mode mixing effects for the l=3, |m|=2 spherical harmonic, and accelerated evaluation trough a variant of multi-banding. We discuss the accuracy of the model and its impact on parameter estimation for current and some planned gravitational wave detectors.

Glampedakis, Kostas

Photon trapping orbits as a diagnostic of non-Kerr spacetimes. In this talk we explore how photon trapping orbits are modified when one moves away from the spherical orbits of Kerr black holes to non-Kerr spacetimes. We discuss the implications for the gravitational wave/electromagnetic signature of non-Kerr compact objects.

Husa, Sascha

The phenomenological waveform program at UIB. The talk will introduce the phenomenological waveform program to model gravitational waves from compact binary coalescence at UIB, and discuss how this is embedded in a systematic exploration of the parameter space of black hole binaries with numerical simulations. I will discuss the modelling methods and input data sets that we use, and planned work for the future. Further talks concerned with details of modelling eccentricity and subdominant spherical harmonics will be submitted separately. I will also discuss the state of our efforts to run parameter estimation analyses on Spanish RES resources.

Levan, Andrew

Near term prospects for gravitational wave — electromagnetic observations. The detection of GW170817 in both gravitational waves and across the electromagnetic spectrum offers a remarkable insight into the promise of multi messenger astrophysics. In this talk I will review what we have learned from GW170817, and discuss what we still need to understand from observations in the LIGO/VIRGO O3 run and once LIGO/VIRGO reaches design sensitivity. This will include the prospects for understanding heavy element enrichment, short duration gamma-ray bursts and measuring the Hubble constant. I will particularly focus on the additional information that EM observations can bring, and on what new observations might be pursued that were not available for GW170817.

Menéndez, Alexis

A convoluted neural network implementation for the search for compact binary signals at Virgo. The detection of Gravitational Waves by LIGO and Virgo in the last few years represented the beginning of a new era in the understanding of the universe. The new observation periods foreseen in 2019, 2021 and 2024, with gradually increasing sensitivities, promise to bring new breakthroughs. In this contribution, we explore the feasibility of a deep-learning implementation for the search for gravitational waves from compact binaries at Virgo. Supervised techniques based on convoluted neural networks, acting on processed images, are employed in order to extract previously injected signal templates in the O2 data. A variety of signal parameters are considered and the results are expressed in terms of an extended reach for binary detection, as well as an improved signal-to-noise ratio as a function of the binary mass and luminosity distance..

Mir, Lluisa-María

Instrumented baffles for Virgo. The IFAE group is developing instrumented baffles around test masses for Virgo in time for the new upgrade of the interferometer in 2023. The construction of baffles instrumented with photon sensors allows for a better understanding of the stray light distribution in the interferometer, offering a new tool for: a much more efficient pre-alignment and fine-tune of the parameters of the interferometer after shutdowns and during operations; the detection and suppression of developing high modes in the interferometer; and the possibility of dynamically feeding back the observed light distributions in the baffles into the description of the mirrors surface. In this contribution, the overview of the project and the technological challenges are presented.

Nesseris, Savas

Gravitational wave energy emission and detection rates of Primordial Black Hole hyperbolic encounters. We describe in detail gravitational wave bursts from Primordial Black Hole (PBH) hyperbolic encounters. The bursts are one-time events, with the bulk of the released energy happening during the closest approach, which can be emitted in frequencies that could be within the range of both LIGO (10-1000Hz) and LISA (10−6−1 Hz). Furthermore, we correct the results for the power spectrum of hyperbolic encounters found in the literature and present new exact and approximate expressions for the peak frequency of the emission. Note that these GW bursts from hyperbolic encounters between PBH are complementary to the GW emission from the bounded orbits of BHB mergers detected by LIGO, and help breaking degeneracies in the determination of the PBH mass, spin and spatial distributions.

Oltean, Marius

On the equations of motion for extreme-mass-ratio inspirals. The gravitational waves emitted by binary systems with extreme mass ratios carry unique astrophysical information expected to be probed by the next generation of space-based gravitational wave detectors such as LISA. The detection of these binaries relies crucially on an accurate modeling of the gravitational self-force - that is, the backreaction of the orbiting body's gravitational field upon its own motion - which is what drives the gravitational wave emission from such systems. We present a novel derivation of their equations of motion, based on conservation laws and formulated independently of the perturbative gauge. In particular, these are obtained with the use of a quasilocal (rather than matter) stress-energy-momentum tensor so as to capture gravitational effects, including the self-force. Our approach offers a fresh geometrical picture from which to understand the self-force fundamentally, and potentially a useful new avenue for computing it practically.

Palenzuela, Carlos

Gravitational waves from binary Exotic Compact Objects. Gravitational wave astronomy might allow us to detect the coalescence of low-brightness astrophysical compact objects which are extremely difficult to be observed with current electromagnetic telescopes. Besides classical sources like black holes and neutron stars, other candidates include Exotic Compact Objects (ECOs), which could exist in theory but have never yet been observed in Nature. Here we consider different possibilities, including Boson Stars (astrophysical compact objects made with a complex scalar field) and Dark Stars (made of dark matter such that they only interact with other stars through gravity). We study numerically the dynamics and the gravitational waves produced during the coalescence of these binaries. These results are compared with the coalescence of classical compact objects, like Black Holes and Neutron Stars. Our analysis indicates that Boson Stars and Dark Stars belong to a new kind of compact objects whose merger produces a gravitational signature clearly distinguishable from classical astrophysical objects.

Pannarale, Francesco

Gravitational Waves from Coalescing Neutron Star Binaries.

Ramos Buades, Antoni

Towards modelling eccentric black-hole binaries. Population synthesis studies show that globular clusters and galactic nuclei may host a population of moderate and high eccentric black-hole binaries emitting gravitational waves in the frequency band of ground-based detectors. The production of gravitational waveform models describing such systems requires calibration to numerical relativity simulations. In this talk, we present a catalog of numerical eccentricity simulations and hybrid waveforms connecting these simulations to post-Newtonian results. We discuss our workflow to generate these data, from prescribing a desired initial eccentricity, carrying out the simulations with an acceptable accuracy for waveform modelling with two available codes, BAM and EinsteinToolkit, to constructing the hybrid waveforms. We discuss open challenges in the post-Newtonian prescription and in numerical simulations, as relevant for the waveform modelling for spinning highly eccentric binaries. Finally, we also show some studies about parameter biases of injected highly eccentric signals in detector gaussian noise when estimating the parameters using quasi-circular models.

Rivas, Francisco

Data and diagnostics dubsystem on board the LISA Pathfinder and LISA missions. LISA and LISA Pathfinder (LPF) are two different but very related ESA missions. LPF launched in 2015 with the objective of testing new technologies which will be needed for the future GW observatory in space: LISA. Since it was a great success, LISA was approved with a preliminary launch date around 2034. It will be a GW observatory in space consisting in 3 spacecrafts separated by 2.5M km which will form a triangle constellation and be able to detect GWs passing by. In this talk we will talk about the different results we obtained analysing the LPF data, and the developments and designs we are actually working on towards LISA. We will also describe all the effects LPF test masses are experimenting due to the temperature and magnetic fields, and how these effects affect its noise level. Finally, we will show these results are actually helping us in the development our group is performing in the LISA Diagnostics Subsystem.

Sanchis-Gual, Nicolas

Gravitational waves from Proca star binaries. Proca stars, aka vector boson stars, are self-gravitating Bose-Einstein condensates obtained as numerical stationary solutions of the Einstein-(complex)-Proca system. These solitonic objects can achieve a compactness comparable to that of black holes, thus yielding an example of a black hole mimicker, which, moreover, can be both stable and form dynamically from generic initial data by the mechanism of gravitational cooling. In this work we further explore the dynamical properties of these solitonic objects by performing both head-on collisions and orbital mergers of equal mass Proca stars, using fully non-linear numerical evolutions. We plan to build a gravitational-wave catalog of Proca star binaries.

Schutz, Bernard

Plenary talk: Cosmology with coalescing binary detections.

Public talk: How Gravitational waves made human evolution possible. The detection by LIGO and Virgo in 2017 of gravitational waves from the very distant merger of two neutron stars has opened up an amazing story, of how Einstein’s gravitational waves actually provided essential ingredients for the evolution of life on Earth. The story begins with a similar merger and explosion that happened rather nearby, just before the Sun formed, and which created all the heavy elements found on Earth, including uranium-238 and thorium-232. The heat generated by the continuing decay of these two isotopes deep inside Earth has been crucial for evolution and is the reason that the most intelligent animals have evolved on land and not in the seas. Without Einstein’s gravitational waves, caused those two long-ago neutron stars to spiral together and collide, we humans would not have evolved on this planet.

Sorazu, Borja

Current status and future of ground-based GW detector networks, from A+ and AdV+ to 3rd generation.

Tenorio Márquez, Rodrigo

Noise-robust strategies for continuous gravitational wave searches. Improvements on the SkyHough all-sky search Rapidly-spinning non-axisymmetric neutron stars may emit continuous quasi-monochromatic gravitational waves, which can be detected by ground-based interferometers like the current Advanced LIGO and Advance Virgo detectors. The SkyHough pipeline [1,2] was developed as a noise-robust data analysis procedure to detect such signals, yielding reliable results under the presence of detector artifacts [3]. We present a novel Robust Statistic which benefits from samplings in the parameter space to mitigate the effect of persistent spectral disturbances on the data. It uses the power-mixing Tau statistic introduced by [4], raising the significance of continuous signals above non-coherent background noise. As a second step, we implement an artificial neural network-based algorithm to deliver continuous wave candidates as clusters of points in the parameter space. This results in a significant increase in sensitivity for the SkyHough pipeline, with no further computational costs after performing the initial setup. [1] The Hough transform search for continuous gravitational waves, B. Krishnan et al., Phys. Rev. D 70, 082001 (2004) [2] Hough search with improved sensitivity, B. Krishnan and A. M. Sintes, LIGO-T07012400Z DCC (2007) [3] Comparison of methods for the detection of gravitational waves from unknown neutron stars, S. Walsh et al., Phys. Rev. D 94, 124010 (2016) [4] Optimal strategies for sinusoidal signal detection, B. Allen, M. A. Papa, B. F. Schutz, Phys. Rev. D 66, 102003 (2002)

Torres-Forné, Alejandro

Universal relations of core-collapse supernova with gravitational waves. We will present the derivation, based in numerical simulations, of the universal relations that relate the frequencies of the most common oscillation modes of the proto-neutron star observed i.e. g-modes, p-modes and the f-mode, with the properties of the system, such as the surface gravity of the proto-neutron star or the mean density in the region enclosed by the shock. We show that the relations do not depend on the equation of state or progenitor star and hence are universal, and, therefore, these relations can be used to build methods to infer proto-neutron star properties from gravitational-wave observations alone.

Veitch, John

Digging compact binary populations out of the noise. The recent detections of coalescing binaries have begun to reveal the how the population of sources are distributed in terms of their masses, spins, and throughout space. The characterisation of these populations has so far been performed using only those sources which have a high probability of being of astrophysical origin, effectively imposing a detection threshold, then using them to estimate population parameters in a hierarchical model. This procedure throws away information contained in sub-threshold triggers which individually have only a low probability of being real signals but together yield information about the population. We present a novel technique which obviates the need for a detection threshold when estimating population parameters, through the use of a mixture model containing both astrophysical and noise transients. This technique allows for uncertainty in the parameters of events actually considered, and is therefore suitable for use with parameter estimates from recent observing runs. Using this model we obtain unbiased estimates of the population parameters even when the data we consider are polluted by a large fraction of noise events. This allows a threshold to be chosen to achieve a desired computational cost rather than to eliminate false alarms.

Wang Qingwen

Echoes from Quantum Black Holes. Exotic compact objects (ECOs) produce the same initial event detected by LIGO-Virgo collabo-ration as classical black holes (BHs), but various quantum gravity models feature different following”echoes”. In particular, we investigate the echoes from the fluctuation-dissipation theorem [1, 2], which changes the dispersion relationship near the (would-be) horizon and results a Boltzmann re-flective boundary. We derive correspondent quasi-normal modes (QNMs) analytically. Further, wemodel the analytical and numerical echoes in the real time, which are consistent with each other.Last, we show that the superradiance is highly suppressed in the theorem.

Watcher, Jeremy

Changes to cosmic string spectra due to gravitational self-interactions. Gravitational self-interactions of cosmic string loops lead to changes in their physical structure, which in turn modifies the gravitational wave spectra we expect these loops to produce. We discuss the analytical predictions of these changes, show examples of modified spectra, and discuss the impact gravitational self-interaction will have on detectability in future experiments.

Zilhao, Miguel

The Physics of Black Hole Binaries: geodesic properties, quasinormal modes and interaction with fundamental fields. Black holes are the simplest macroscopic objects and provide unique tests of General Relativity. They can be compared to the Hydrogen atom in quantum mechanics, and in this same fashion one can think of black hole binaries as the simplest "gravitational molecules". We here report on our ongoing study of the physics of such systems, and present results concerning geodesic and quasinormal mode properties of these spacetimes as well as their interaction with fundamental fields.