XXV SIGRAV Conference on General Relativity and Gravitation

Session

Parallel Sessions

Sep 4, 2023, 2:00 PM

Aula Magna, Room A, B, D (SISSA (Miramare campus))

30. Experiments: Status of the GINGER project

Angela Di Virgilio

9/4/23, 2:00 PM

The measurements of the Earth rotation rate variations, certainly important for Earth science, are relevant also for fundamental physics investigation, as they contain general relativity terms, such as de Sitter and Lense Thirring, and they provide unique data to investigate Lorentz violations. Long term continuous operation and very high sensitivity are required, the limit to be reached to...

15. Phenomenology: Detection and measurement prospects at the Einstein Telescope: forecasts with GWFAST

Francesco Iacovelli (University of Geneva)

9/4/23, 2:00 PM

The detection of gravitational waves in 2015, thanks to the LIGO and Virgo interferometers, opened a new window on our Universe. The discoveries during the first three observing runs already had an extraordinary impact on both astrophysics, cosmology, and fundamental physics.

The GW community is now looking at the next long–prepared step: ‘third–generation’ detectors. Thanks to an increase...

8. Theory: Exploring Conserved Charges in General Relativity Using Covariant Phase Space

Gloria Odak (CPT Marseille)

9/4/23, 2:00 PM

Theory

In this talk, we delve into the application of the covariant phase space formalism to the study of conservation laws in General Relativity. Our focus is twofold: firstly, we demonstrate the association of the Carter constant with a genuine conserved Noether charge, utilizing the powerful tool provided by the covariant phase space. Secondly, we explore the dependence of the construction of...

214. Theory: The quantum states of the universe in tomographic form

Cosimo Stornaiolo (INFN-Sezione di Napoli)

9/4/23, 2:15 PM

In this talk I present some new results in the program of formulating Quantum Cosmology in a tomographic representation. In particularI I show new solutions of the Wheeler-De Witt equation recently obtained together with the correspondent tomograms.

22. Experiments: Fundamental Physics with GNSS satellites and the Galileo for Science Project

Feliciana Sapio (IAPS-INAF)

9/4/23, 2:30 PM

Agency (ASI) that aims to provide Fundamental Physics measurements with the Galileo-FOC constellation of the Global Navigation Satellites System (GNSS). The measurements concern both the analysis of satellite orbits and of their atomic-clocks data. A new accurate analysis of the satellites onboard atomic-clocks can lead to the following significant results: i) measuring the gravitational...

17. Phenomenology: Parameter estimation of binary black holes in the endpoint of the up--down instability

Viola De Renzis (University of Milano-Bicocca)

9/4/23, 2:30 PM

Black-hole binary spin precession admits equilibrium solutions corresponding to systems with (anti-) aligned spins. Among these, binaries in the up-down configuration, where the spin of the heavier (lighter) black hole is co- (counter-) aligned with the orbital angular momentum, might be unstable to small perturbations of the spin directions. The occurrence of the up-down instability leads to...

9. Theory: On the classification of Generalized Quasitopological Gravities

Ángel Jesús Murcia Gil (Istituto Nazionale di Fisica Nucleare, Sezione di Padova (Italia))

9/4/23, 2:30 PM

Generalized Quasitopological Gravities (GQTGs) are higher-order extensions of Einstein gravity in D dimensions satisfying a number of interesting properties, such as possessing second-order linearized equations of motion on top of maximally symmetric backgrounds, admitting non-hairy generalizations of the Schwarzschild-Tangherlini black hole which are characterized by a single metric function...

199. Theory: On the canonical equivalence of Jordan and Einstein frames

Gabriele Gionti, S.J. (Specola Vaticana (Vatican Observatory) and LNF-INFN Frascati)

9/4/23, 2:45 PM

A longstanding issue is the equivalence between the Jordan and the Einstein frames. It is believed, but not completely proved, that the cosmological physical observables are the same in the two frames. Our aim is to tackle this problem from the perspective of the Hamiltonian formalism. For this reason, we will perform the Hamiltonian analysis of the Brans-Dicke theory with Gibbons-Hawking-York...

24. Experiments: METRIC: a mission concept for upper atmosphere mapping, gravitational physics and geodesy

Roberto Peron (INAF-IAPS)

9/4/23, 3:00 PM

We describe here a mission concept - called METRIC (Measurement of EnvironmenTal and Relativistic In-orbit preCessions) - for a spacecraft to be placed in a low Earth orbit, with dedicated instrumentation to provide data useful for atmospheric science, fundamental physics and geodesy. The main scientific objectives are: map the atmospheric density by in-situ acceleration measurement and by...

19. Phenomenology: Multitimescale dynamics of eccentric and precessing binary black holes

Giulia Fumagalli (University of Milano-Bicocca)

9/4/23, 3:00 PM

Understanding the dynamics of binary black holes is crucial to extract information from gravitational-wave data. By now, a consistent amount of effort has been put into exploring the phenomenology of black-hole binaries in the Post-Newtonian regime that evolve on quasi-circular orbits and undergo spin precession. We present substantial advances in this area using a multi-timescale approach to...

10. Theory: On the nature of Bondi-Metzner-Sachs transformations

Giampiero Esposito (University Federico II Naples and INFN Naples Section)

9/4/23, 3:00 PM

This work investigates, as a first step, the four branches of BMS
transformations, motivated by the classification into elliptic, parabolic,
hyperbolic and loxodromic proposed a few years ago in the literature. We
first prove that to each normal elliptic transformation of the complex
variable z used in the metric for cuts of null infinity, there is a
corresponding BMS supertranslation. We...

21. Phenomenology: Anisotropic Neutron Stars: Exploring Quasinormal Modes in Full General Relativity

Sushovan Mondal (The Institute of Mathematical Sciences, Chennai, India)

9/4/23, 3:15 PM

The discovery of the Hulse Taylor pulsar gave indirect evidence of gravitational waves, but recent groundbreaking direct detection of gravitational waves by LIGO-VIRGO collaboration opened a new window to look at the celestial entities and cosmos. In this work we focus on exploring the impact of local anisotropic pressure on the quasinormal modes of neutron stars in the framework of general...

11. Theory: Can General Relativity Play a Role in Galactic dynamics?

Matteo Luca Ruggiero (Università degli Studi di Torino and INFN - LNL)

9/4/23, 3:15 PM

There have been some recent claims about the impact of general relativistic corrections on the dynamics of galaxies, with possible implications for their dark matter content. We examine and analyze the proposed models to discuss their reliability and limitations. Then, we focus on the properties of an exact solution of Einstein's equations describing a self-gravitating system, made of dust,...

26. Experiments: Galactic Dark Matter from General Relativity

Federico Re (Milano Bicocca)

9/4/23, 4:00 PM

General relativistic models of disc galaxies can provide non negligible corrections with respect the Newtonian description, for the rotation speeds and their relationship to the required gravitational mass. This result can be counterintuitive, for an object with sub-relativistic speeds such as a galaxy; but General Relativity (GR) does not only provide higher order, post-Newtonian corrections...

25. Phenomenology: Glitch systematics on the observation of massive black-hole binaries with LISA

Alice Spadaro (University of MIlano-Bicocca)

9/4/23, 4:00 PM

Detecting and coherently characterizing thousands of gravitational-wave signals is a core data-analysis challenge for the Laser Interferometer Space Antenna (LISA).Transient artifacts, or “glitches”, with disparate morphologies are expected to be present in the data, potentially affecting the scientific return of the mission. We present the first joint reconstruction of short-lived...

200. Theory: Probing the Big Bang with Quantum Fields

Marc Schneider (SISSA)

9/4/23, 4:00 PM

The singularity theorems of Penrose and Hawking are based on geodesic incompleteness and predict the occurrence of classical singularities under rather general circumstances. In general relativity, these singularities represent absolute boundaries where space-time ends.
Physically, however, this criterion refers to the fate of point like classical test particles. We raise the question: What...

216. Phenomenology: Non-gaussian gravitational wave backgrounds across the GW spectrum

Riccardo Buscicchio (Università di Milano-Bicocca)

9/4/23, 4:15 PM

Stochastic gravitational wave backgrounds (SGWBs) are, to date, yet to be unequivocally observed. At the 𝑛𝐻𝑧 frequencies, tentative evidence for the observation of such signals has been recently reported.

In this talk, I will focus on prospects for the detection of SGWBs of astrophysical origin in the 10−4𝐻𝑧−103𝐻𝑧 frequency range.
I will show how recent progress in statistics and...

12. Theory: Primordial fluctuations from quantum gravity

Francesca Vidotto (Western University, Canada)

9/4/23, 4:15 PM

In modern cosmology there is an agreement that the seeds of structure formations reside in the quantum fluctuation of the geometry in the early universe, but there is no agreement about how these could be derived from a quantum theory of gravity. In this talk I present a proposal based on the covariant formulation of Loop Quantum Gravity. I describe how to define a wavefunction of the universe...

18. Experiments: ISA accelerometer on-board BepiColombo mission during first Mercury swing-bys – Preliminary observations

Francesco Santoli (IAPS-INAF)

9/4/23, 4:30 PM

217. Phenomenology: From regular black holes to horizonless objects: gravitational perturbations and detectability

Vania Vellucci (Sissa)

9/4/23, 4:30 PM

Black holes represents a break down of General Relativity because of the presence of the central singularity where the space-time is no more defined and the theory is no more predictive. There are two possible alternatives to black holes to describe the compact objects that we see in our Universe: regular black holes whose horizon hides a regular core and ultracompact horizonless objects. I...

13. Theory: Scale-invariant inflation

Chiara Cecchini (University of Trento, TIFPA-INFN)

9/4/23, 4:30 PM

Fundamental scale invariance has been proposed as a new theoretical principle beyond renormalizability. Besides its highly predictive power, a scale-invariant formulation of gravity could provide a natural explanation for the long-standing hierarchy problem and interesting applications in cosmology.
We present a globally scale-invariant model of quadratic gravity and study its solutions in a...

29. Phenomenology: AGILE search of gamma-ray electromagnetic counterparts of gravitational waves

Francesco Longo

9/4/23, 4:45 PM

AGILE is an Italian Space Agency (ASI) space mission devoted to gamma-ray observations
in the 30 MeV - 50 GeV energy range, with simultaneous X-ray imaging in the 18-60 keV
band. Launched in April 2007, the AGILE satellite, with more than 16 years of observation
in orbit, is substantially contributing to improve our knowledge of the gamma-ray sky.
Thanks to its very fast ground segment...

14. Theory: Bianchi-I cosmologies, magnetic fields and singularities

Alexander Kamenshchik (INFN)

9/4/23, 4:45 PM

We study the effects of a spatially homogenous magnetic field in Bianchi-I cosmological models. In particular, we review the case of a pure magnetic field and two models with dust and a massless scalar field (stiff matter), respectively. For all these cases, we analyse the approach to the singularity in some details and comment about the issue of the singularity crossing.

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201. Theory: A Cosmographic distance functional between Celestial Spheres

Francesca Familiari (Università di Pavia, INFN)

9/4/23, 5:00 PM

The standard model of cosmology, known as the ΛCDM model, is based on the Friedmann-Lemaître-Robertson-Walker (FLRW) class of models. It successfully describes the energy composition of the universe, with 68.3% attributed to Dark Energy, 26.8% to Dark Matter, and 4.9% to Ordinary Matter. However, it leaves us with the challenge of understanding the nature of the Dark Universe. The model...

210. Theory: Grand canonical ensemble of a d-dimensional Reissner-Nordström black hole space in a cavity

Tiago Fernandes (GRIT - CENTRA, IST)

9/4/23, 5:15 PM

The grand canonical ensemble of a d-dimensional
Reissner-Nordström black hole space in a cavity is analyzed through
the Euclidean path integral approach. The partition function of the
ensemble is given in terms of the fixed temperature and fixed electric
potential at the boundary of the cavity. One performs the zero loop
approximation, i.e., only the contribution of the solutions which...

50. Experiments: Detecting low-frequency gravitational waves with Pulsar Timing Arrays

Delphine Perrodin (INAF - Osservatorio Astronomico di Cagliari)

9/5/23, 2:00 PM

Pulsars are highly-magnetized, rapidly-rotating neutron stars that emit beams of radio waves from their magnetic poles. Due to the misalignment of the magnetic and rotation axes of the pulsar, our radio telescopes on Earth can detect a pulse for each rotation of the pulsar as in the ‘lighthouse effect’. Monitoring those pulses and their arrival times at radio telescopes is called “pulsar...

49. Phenomenology: Scalar-tensor theories to tackle cosmological tensions

Mario Ballardini (University of Ferrara)

9/5/23, 2:00 PM

We investigate different extended scalar-tensor theories of gravity. Particularly, we study the theory in the Jordan frame with different non-minimal coupling, with a standard and non-standard kinetic term, and the impact of a cubic interaction term. The nonminimally coupled scalar field, regulating the gravitational strength, moves around recombination because of its coupling to pressureless...

51. Theory: Beyond the Casimir Wormholes

Remo Garattini (Università degli Studi di Bergamo)

9/5/23, 2:00 PM

After a brief description of what is a traversable wormhole we describe the connection between traversability and the Casimir effect. With the help of an equation of state we also discuss different form of solutions generated by the Casimir source. Yukawa deformations and the addition of an electromagnetic field to the original energy density are also discussed.

204. Theory: Lessons from gravitational physics and beyond: how can we rethink space, time and causal order?

Silvia De Bianchi (University of Milan)

9/5/23, 2:15 PM

The first part of this contribution highlights the main results of the ERC project PROTEUS with regard to the conceptual difficulties encountered in current quantum gravity approaches. The second part of the talk is devoted to the discussion of more recent work on the foundations of quantum gravity with emphasis on their impact on the philosophical understanding of space, time and causal...

56. Experiments: The European Pulsar Timing Array - the pulsar dataset

Golam Shaifullah (Dipartimento di Fisica ``G. Occhialini", Universit{\'a} degli Studi di Milano-Bicocca, Piazza della Scienza 3, I-20126 Milano, Italy)

9/5/23, 2:30 PM

I will present the second data release of the European Pulsar Timing Array (EPTA), containing high-precision pulsar timing data for 25 millisecond pulsars collected with five of the largest radio telescopes in Europe as well as the Large European Array for Pulsars. This dataset forms the basis for the gravitational wave searches carried out by the EPTA. I will also present results from the...

55. Phenomenology: Observational phenomena on black hole with dark matter dress

Xing-Yu Yang (Korea Institute for Advanced Study)

9/5/23, 2:30 PM

The accretion of dark matter around the black hole could lead to the formation of surrounding halo. Such a dark matter dressed black hole can leave characteristic imprints in the observations including gamma-ray, gravitational lensing and gravitational waves. In this talk, I will talk several observational phenomena on the black hole with dark matter dress.

54. Theory: Fundamental decoherence from quantum spacetime

Vittorio D'Esposito (University of Naples Federico II)

9/5/23, 2:30 PM

Quantum properties of spacetime can affect the evolution of quantum systems. We discuss this in a noncommutative spacetime setting, showing that the standard Liouville-von Neumann equation is replaced by a Lindblad equation. This leads to a decoherence mechanism by which pure states can evolve into mixed states. The decoherence time for the evolution of a free particle is used to show that the...

61. Phenomenology: Non-ideal GRMHD and compact objects

Luca Del Zanna (Università di Firenze)

9/5/23, 2:45 PM

I will present the general formalism for including resistive dissipation and mean-field dynamo amplification of magnetic fields in the set of GRMHD equations, needed to simulate numerically the relativistic plasmas in the environment of compact objects. A selection of applications will be discussed, from the exponential growth and saturation of magnetic fields in thick tori around black holes...

60. Theory: Carrollian and Galilean limits of deformed symmetries in 3D gravity

Tomasz Trzesniewski (University of Wroclaw)

9/5/23, 2:45 PM

Non-Lorentzian kinematical symmetries, especially the ones corresponding to the Galilei or Carroll relativistic limits (i.e., the speed of light taken to infinity or to zero), are nowadays the subject of vigorous investigations. This also concerns (quantum) deformations of such symmetries, described in the formalism of Lie bialgebras and Hopf algebras. The case of 2+1-dimensional spacetime is...

68. Experiments: The second data release from the European Pulsar Timing Array II. Customised Pulsar Noise Models for Spatially Correlated Gravitational Waves

Aurélien Chalumea

9/5/23, 3:00 PM

The subtle imprints that the gravitational wave background (GWB) induces on pulsar timing data are obscured by many sources of noise that occur on various timescales. These must be carefully modelled and mitigated to increase the sensitivity to the background signal. In this talk, I will present novel techniques and methodologies developed for robustly estimating the noise budget in 25...

67. Phenomenology: Dark Matter in Fractional Gravity I: Astrophysical Tests on Galactic Scales

francesco benetti (SISSA)

9/5/23, 3:00 PM

We explore the possibility that the dark matter (DM) component in galaxies may originate fractional gravity. In such a framework, the standard law of inertia continues to hold, but the gravitational potential associated to a given DM density distribution is determined by a modified Poisson equation including fractional derivatives (i.e., derivatives of non-integer type), that are meant to...

66. Theory: Quantum Euler angles and agency-dependent spacetime

Giuseppe Fabiano (University of Naples "Federico II")

9/5/23, 3:00 PM

Quantum gravity is expected to introduce quantum aspects into the description of reference frames. Here we set the stage for exploring how quantum gravity induced deformations of classical symmetries could modify the transformation laws among reference frames in an effective regime. We invoke the quantum group 𝑆𝑈𝑞(2) as a description of deformed spatial rotations and interpret states of a...

218. Phenomenology: Ultraviolet Sensitivity of Peccei–Quinn Inflation

Davide Dal Cin (Sissa)

9/5/23, 3:15 PM

The radial direction of the Peccei–Quinn field can drive cosmic inflation, given
a non-minimal coupling to gravity. This scenario has been considered to simultaneously
explain inflation, the strong CP problem, and dark matter. We argue that Peccei–Quinn
inflation is extremely sensitive to higher-dimensional operators. Further combining with the
discussion on the axion quality required for...

205. Theory: A quantum-spacetime model with kinematical IR/UV mixing and its phenomenology

Domenico Frattulillo (University of Naples "Federico II")

9/5/23, 3:15 PM

I present a doubly special relativistic model inspired from the k-lightlike non-commutative spacetime framework. A kinematical IR/UV mixing mechanism emerges naturally from the deformed energy-momentum dispersion relation, when considering particles with very small speeds. Thus, this model is suited for studying Planck-scale corrections to atom interferometry experiments.

74. Experiments: Impications of GW searches in the latest data release of the EPTA

Alberto Sesana (Universita` di Milano Bicocca)

9/5/23, 4:00 PM

EPTA has been taking data for 25 years and has now uncovered the first hint of a common signal in the data. I will discuss what are the consequences on this results for the astrophysics of supermassive black hole binary, processes in the early universe and specific models of dark matter.

73. Phenomenology: Testing Planck-scale in-vacuo dispersion with GRB neutrinos

Giacomo Rosati (Institute of Theoretical Physics, Wrocław University)

9/5/23, 4:00 PM

GRB (gamma-ray-burst) neutrinos are excellent probes for testing quantum-gravity-induced in-vacuo dispersion. In this scenario, inspired by quantum gravity research and associated with Lorentz Invariance Violation (LIV), empty quantum spacetime behaves like a dispersive medium affecting the propagation of ultrarelativistic particles, whose speed is affected by energy-dependent Planck-scale...

72. Theory: Axially symmetric stationary gravitational perturbations of Kerr black hole --- Debye vs Weyl\,--\,Lewis\,--\,Papapetrou

David Kofron (Institute of Theoretical Physics, Faculty of Mathematics and Physics, Charles University)

9/5/23, 4:00 PM

The axially symmetric stationary gravitational perturbations of Kerr black hole are analyzed (a) within the framework of the Debye potentials as well as (b) a perturbations of Kerr black hole within the Weyl\,--\,Lewis\,--\,Papapetrou class of metrics. We find the exact explicit calibration transformation which is needed to connect the metric perturbations in this approach. We also provide the...

219. Phenomenology: Anharmonic effects on the squeezing of axions perturbations

Valentina Danieli (SISSA)

9/5/23, 4:15 PM

It is well known in cosmology that the history of the Universe undergoes a period of quasi exponential expansion. The fluctuations of the inflaton field are believed to have a quantum origin, however the CMB sky we observe today is classical. Therefore the questions whether the initial perturbations have a quantum or classical origin and how to discriminate them arise. Actually inflation...

78. Theory: To Kerr or not to Kerr?

Polina Petriakova (INFN)

9/5/23, 4:15 PM

This talk is devoted to an examination of the Newman-Janis algorithm's application to an exact regular static black hole' solution. We observe that the rotating extension obtained with the NJA cannot be described in terms of the same scalar field energy-momentum tensor, with deviations that are somehow 'confined' to a small region. It raises an interesting question about what to trust about...

80. Experiments: The growing population of the relativistic pulsar binaries

Andrea Possenti (INAF-Osservatorio Astronomico di Cagliari)

9/5/23, 4:30 PM

The presentation introduces the growing family of the relativistic binary pulsars, highlighting some of the most recent intriguing outcomes resulting from the observations of these systems. In particular the focus will be on the last news from the investigation of the double-pulsar binary PSR J0737-3039. Finally, the perspectives from continuing the monitoring of these systems with present and...

79. Phenomenology: A new Paradigm for the Dark Matter Phenomenon

Paolo Salucci (SISSA)

9/5/23, 4:30 PM

The phenomenon of the Dark matter baffles the researchers: the underlying dark particle has escaped so far the detection and its astrophysical role appears complex and entangled with that of the standard luminous particles. We propose that, in order to act efficiently, alongside with abandoning the current scenario, we need also to shift the Paradigm from which it emerged.

206. Theory: On the dynamics of perturbed Black Holes

Michele Lenzi (Institute of Space Sciences (ICE-CSIC, IEEC), Barcelona)

9/5/23, 4:30 PM

Perturbation theory of vacuum spherically symmetric spacetimes is a crucial tool for understanding the dynamics of black hole (BH) perturbations as well as BH scattering phenomena. Since the pioneering work of Regge and Wheeler it is known that the equations for the perturbations can be decoupled in terms of (gauge-invariant) master functions that satisfy 1 + 1 wave equations. However, while...

85. Phenomenology: Enlightening Cold Dark Matter's darkest side via a non-minimal coupling

Giovanni Gandolfi (SISSA)

9/5/23, 4:45 PM

The cold dark matter (CDM) paradigm has proven to be relatively successful on cosmological scales, but struggles in fully describing the observed phenomenology on (sub)galactic scales. In this picture, two long-standing issues are the well-known cusp-core controversy and the existence of several tight scaling laws between dark and baryonic quantities, whose explanation is not trivial in the...

207. Theory: Regular Black Holes in Lorentz-violating Gravity

Jacopo Mazza (SISSA, Trieste)

9/5/23, 4:45 PM

There is growing evidence that Hořava gravity may be a viable quantum theory of gravity. It is thus legitimate to expect that gravitational collapse in the full, non-projectable version of the theory should result in geometries that are free of spacetime singularities. Previous analyses have shown that such geometries must belong to one of the following classes: simply connected regular black...

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91. Phenomenology: Spectrogram correlated stacking: A time-frequency domain analysis of the Stochastic Gravitational Wave Background

Ramit Dey (Western University, perimeter institute)

9/5/23, 5:00 PM

The stochastic gravitational wave background (SGWB) originates from numerous faint gravitational wave (GW) signals arising from coalescing compact binary objects. Based on the currently estimated merger rate, where the binary merger events are Poisson-distributed at any instance, the SGWB signal is expected to originate from non-overlapping GW signals. Current efforts to detect this signal...

208. Theory: Black-hole evolution in the presence of scalar fields

Marco De Cesare

9/5/23, 5:00 PM

I will present recent analytical results on the evolution of the trapping horizon of a spherically symmetric black hole, as due to the backreaction of scalar radiation on the geometry in the low-frequency approximation. A simple closed-form expression can be derived for the expansion rate of the horizon in terms of initial data for the scalar field on past null infinity. This is obtained by...

220. Phenomenology: Primordial Black Holes during the QCD phase-transition

Dr Ilia Musco (INFN, La SAPIENZA University of Rome)

9/5/23, 5:15 PM

Primordial black holes (PBHs) could have been formed in the very early Universe from large amplitude perturbations of the metric. Their formation is naturally enhanced during the quark-hadron phase transition, because of the softening of the equation of state: at a scale between 1 and 3 solar masses, the threshold is reduced of about 10% with a corresponding abundance of PBHs significantly...

209. Theory: Unveiling Novel Scalarized Black Hole Solutions in Modified Theories

Zakaria Belkhadria (Université de Genève / Universita di Cagliari/ INFN theory)

9/5/23, 5:15 PM

This presentation delves into the study of 'hairy' black holes within the framework of Einstein scalar Maxwell gravity and Einstein scalar Gauss-Bonnet theories, with a focus on revealing new scalarized black hole solutions. We revisit established scalarization phenomena and venture into new solution territories, particularly highlighting the blend of linear and non-linear scalarization in...

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202. Theory: Quantum field corrections to the equation of state of freely streaming matter in the FLRW space-time

Francesco Becattini

9/5/23, 5:30 PM

We calculate the energy density and pressure of a scalar field after its decoupling from a thermal bath in the spatially flat Friedman-Lemaı̂tre-Robertson-Walker space-time, within the framework of quantum statistical mechanics. By using the density operator determined by the condition of local thermodynamic equilibrium, we calculate the mean value of the stress-energy tensor of a real scalar...

52. Experiments: The Astrometric Gravitational Arena: principles and applications

Mariateresa Crosta

9/7/23, 2:00 PM

This talk aims to present the potential of gravitational astrometry as a tool for peering into the fabric of spacetime exclusively using stellar astrometry. Once prescribed a suitable set of geometries and observers, a multiscale investigation consistent with general relativistic-compliant astrometry allows testing general relativistic scenarios for our Galaxy as well as tiny angular...

53. Phenomenology: Neural Posterior Estimation with guaranteed exact coverage: the ringdown of GW150914

Marco Crisostomi (SISSA)

9/7/23, 2:00 PM

I will present the analysis of the ringdown phase of the first detected black-hole merger, GW150914, using a simulation-based inference pipeline based on masked autoregressive flows. We obtain approximate marginal posterior distributions for the ringdown parameters, namely the mass, spin, and the amplitude and phases of the dominant mode and its first overtone. Thanks to the locally amortized...

48. Theory: Bouncing and emergent cosmology from Dark Energy with an unstable de Sitter vacuum

Marco Bruni (University of Portsmouth)

9/7/23, 2:00 PM

Dark energy (DE) typically violates the same energy conditions that imply cosmological singularities, hence a DE that dominates at high energy can produce a singularity-free cosmology. If the DE conservation equation admits a high-energy fixed point, this represents an unstable de Sitter vacuum: for flat and open FLRW models this de Sitter state represents the past attractors for what then is...

57. Theory: On the wormhole-warp drive correspondence

Kirill Zatrimaylov (Università degli Studi di Bergamo)

9/7/23, 2:15 PM

As was shown by Ellis in gr-qc/0411096, one can establish a correspondence between the Schwarzschild metric and a particular Natario warp drive metric, making it possible for a warp drive spaceship to cross the black hole horizon. We generalize this result to Morris-Thorne wormholes and demonstrate that wormholes without horizons can be mapped to a different "quasi-Natario" class of metrics...

58. Experiments: Progress on the Astrometric Gravitational Wave Antennas

Mario G. Lattanzi

9/7/23, 2:30 PM

The operational tenets of an antenna for measuring strength and pin-point direction of Gravitational Waves, based on (sub)micro-arcsecond astrometric monitoring of resolved optical pairs, are reviewed before addressing the technologies (including computational) being considered and developed under different initiatives for its realization.

Along with the space option, by far the most...

59. Phenomenology: Testing black hole eikonal correspondence

Che-Yu Chen (iTHEMS, RIKEN)

9/7/23, 2:30 PM

Adopting geometric-optics approximations in black hole spacetimes enables the construction of a mapping between black hole images and eikonal black hole quasinormal modes (QNMs). More explicitly, the real part and imaginary part of the QNM frequencies correspond to the ring size and the detailed ring structure of the image, respectively. This correspondence may be violated when going beyond...

63. Theory: Casimir wormholes with a scalar field

Athanasios Tzikas (University of Bergamo)

9/7/23, 2:30 PM

We investigate possible manifolds characterizing traversable wormholes under the existence of a scalar field that is minimally coupled to gravity and has a kinetic and a potential energy. The feature of traversability requires the violation of the null energy condition followed by the existence of an exotic matter providing a negative energy density to the system. For this reason, we use a...

65. Phenomenology: Hunting for two rings in black hole images

Raúl Carballo-Rubio (CP3-Origins, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark)

9/7/23, 2:45 PM

New physics beyond general relativity can modify image features of black holes and increase the separation between photon rings. For horizonless objects, new physics can generate a set of inner photon rings. Both cases motivate the exploration of synthetic images consisting of two rings. The talk will be focused on assessing the detectability of these features using closure quantities, with...

69. Theory: Geometry of the black-to-white hole transition

Farshid Soltani (Western University)

9/7/23, 2:45 PM

The Oppenheimer-Snyder model is the prototypical example of black hole formation by gravitational collapse. It predicts that a black hole horizon is formed once a star collapses to within its own Schwarzschild radius. After that, the collapsing matter reaches Planckian densities in a short proper time. What happens next is outside the reach of general relativity, as it involves the quantum...

70. Experiments: LISA Pathfinder and LISA test-mass charging

Catia Grimani

9/7/23, 3:00 PM

71. Phenomenology: Testing GR with large catalogs: the cosmic variance of hierarchical stacking

Costantino Pacilio (Università degli Studi di Milano Bicocca)

9/7/23, 3:00 PM

Testing the strong gravity regime of general relativity is a primary goal of gravitational wave detectors. While it is expected that corrections to GR are small and unlikely to be identified with individual events, third generation GW detectors will allow to detect tens-of-thousands of events per year. Therefore, they will pave the way to precision tests by carefully stacking all the detected...

211. Theory: Quantum integrable black holes

Andrea Giusti (ETH Zurich)

9/7/23, 3:00 PM

We consider black holes generically sourced by quantum matter described by regular wavefunctions. This allows for integrable effective energy densities and the removal of Cauchy horizons in spherically symmetric configurations. Moreover, we identify the ultrarigid rotation of the Kerr spacetime as causing the existence of an inner horizon in rotating systems, and describe general properties...

221. Phenomenology: Measuring deviations from the Kerr geometry with black hole ringdown

Kallol Dey (Indian Institute of Science Education and Research, Thiruvananthapuram)

9/7/23, 3:15 PM

Black holes in General Relativity are famously characterized by two "hairs" only, the mass and the spin of the Kerr spacetime. Theories extending General Relativity, however, allow in principle for additional black hole charges, which will generally modify the multipole structure of the Kerr solution. Here, we show that gravitational wave observations of the post-merger ringdown signal from...

212. Theory: Constructing accelerating NUT black holes

José Barrientos (Universidad de Tarapacá)

9/7/23, 3:15 PM

We employ Ehlers transformations, Lie point symmetries of the Einstein field equations, to efficiently endorse accelerating metrics with a nontrivial NUT charge. Under this context, we begin by re-deriving the known C-metric NUT spacetime described by Chng, Mann, and Stelea in a straightforward manner, and in the new form of the solution introduced by Podolský and Vrátný. Next, we construct...

82. Experiments: Large area space interferometry to measure Solar and galactic gravitomagnetism

Massimo Bassan

9/7/23, 4:00 PM

77. Phenomenology: Constraining modifications of black hole perturbation potentials near the light ring with quasinormal modes

Sebastian Völkel (Max Planck Institute for Gravitational Physics (Albert Einstein Institute))

9/7/23, 4:00 PM

In modified theories of gravity, the potentials appearing in the Schrödinger-like equations that describe perturbations of non-rotating black holes are also modified. In this talk, we ask how such modifications can be constrained with future, high-precision measurements of quasi-normal modes. We use a perturbative framework that allows one to map modifications of the effective potential, in...

75. Theory: Vacuum entanglement in near extremal black holes

Salvatore Ribisi (Centre de Physique Théorique - Marseille)

9/7/23, 4:00 PM

The notion of particles is ambiguous in curved spacetimes. This often makes it difficult to explicitly picture the process of Hawking radiation in terms of pair creation of particles (one going to infinity as Hawking radiation and the other falling into the singularity).
I will show how such a difficulty can be circumvented in the case of near extremal black holes in 4d for scale invariant...

83. Phenomenology: Spacetime-Symmetry Breaking and the Generation of Gravitational Waves

Nils Nilsson (SYRTE, l'Observatoire de Paris)

9/7/23, 4:15 PM

Recently, the search for departures from the symmetries of General Relativity has received significant attention in the literature. In this talk, I outline the techniques for probing the nature of spacetime symmetries using the generation stage of gravitational waves. By using a generic effective-field theory, I show our solution scheme of the modified Einstein equations and I write down the...

213. Theory: Hawking Radiation without Lorentz Invariance

Francesco Del Porro (SISSA)

9/7/23, 4:15 PM

It's a well-known fact that Lorentz Violating (LV) theories of gravity, such as Horava-Lifshitz gravity, highlight possibility of a renormalizable, non-Lorentz-invariant UV completion of General Relativity (GR).
On the phenomenological side, the breaking of Local Lorentz Invariance gives a different notion of causality, for which the LV-Black Hole solutions assume a different internal...

230. LAG- Liquid Actuated Gravity - Snooping Inverse Square Law at  cm distance

Massimo Bassan (University of Roma Tor Vergata, Roma, Italy)

9/7/23, 4:30 PM

89. Phenomenology: Test of the Second Postulate of Relativity from Gravitational Wave Observations

Sreejith Nair (Indian Institute of Technology(IIT) Gandhinagar)

9/7/23, 4:30 PM

The second postulate of special relativity states that the speed of light in vacuum is independent of the emitter's motion. The test of this postulate so far remains unexplored for gravitational radiation. We analyzed data from the LIGO-Virgo detectors to test this postulate within the ambit of emission models, where the speed of gravitational waves emitted by a source moving with a velocity 𝑣...

238. Theory: Noncommutative Correction to Black Hole Entropy

Filip Požar

9/7/23, 4:30 PM

Noncommutative geometry is an established potential candidate for including quantum phenomena in gravitation. We outline the formalism of Hopf algebras and its connection to the algebra of infinitesimal diffeomorphisms. Using a Drinfeld twist we deform spacetime symmetries, algebra of vector fields and differential forms leading to a formulation of noncommutative Einstein equations. We study a...

95. Phenomenology: Orthogonality and transitions between black-hole quasibound states

enrico cannizzaro (La Sapienza University of Rome)

9/7/23, 4:45 PM

It is well known that the response of a black hole (BH) to an external perturbation consists in a series of damped sinusoids, dictated by complex frequencies called quasi-normal modes (QNMs). Massive fields also admit a different family of solutions called quasi-bound states (QBSs). Both families of modes dissipate energy at the BH horizon, and QNMs also radiate at infinity. This dissipation...

87. Theory: Renormalization and untarity in an higher derivative scalar theory

Diego Buccio (SISSA, INFN)

9/7/23, 4:45 PM

Higher derivative theories could give a resolution to the problem of renormalizablity of quantum gravity as a quantum field theory. I will describe a simple shift symmetric scalar field model with a higher derivative kinetic term and discuss its main properties concerning unitarity and RG flow. The running of the parameters is found both by calculating the two-point and 4-point amplitudes in...

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9/7/23, 5:00 PM

222. Phenomenology: Nonlinear photon-plasma interaction and the black-hole superradiant instability

Fabrizio Corelli ("Sapienza" University of Rome)

9/7/23, 5:00 PM

Superradiant scattering provides a interesting way of extracting energy from a rotating black hole by means of amplification of low-frequency electromagnetic (EM) radiation. If plasma in the accretion disk prevents the outgoing radiation from escaping to infinity, this process can happen repeatedly, triggering an instability that can lead to the appearance of bursts.
However, investigating...

93. Theory: Mapping the landscape of gravity theories

Serena Giardino (Max Planck Institute for Gravitational Physics & Heidelberg University)

9/7/23, 5:00 PM

Both Einstein's equations and the field equations of a modified theory of gravity can be derived as equations of state from purely thermodynamical considerations, leading to the identification of GR with an equilibrium state of gravity and modified gravity with a non-equilibrium one. This breakthrough made the relationship between gravity and thermodynamics even more intriguing. I will present...

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9/7/23, 5:15 PM

198. Theory: Self gravity affects quantum states

David Edward Bruschi (Institute for Quantum Computing Analytics (PGI-12), Forschungszentrum Jülich)

9/7/23, 5:15 PM

We study how self gravitation of quantum systems affects the quantum coherence present in their state. Spatial superpositions of static, large, heavy systems tend to rapidly lose coherence, whereas light or massless particles are unaffected. Furthermore, large and heavy objects also rapidly localize into a single classical position. The ratio of the characteristic size of the system and its...

215. Theory: Aspects of kinetic screening - UV completion and the two-body problem

Mateja Boskovic (SISSA)

9/7/23, 5:30 PM

New light scalar degrees of freedom may alleviate the dark matter and dark energy problems, but if coupled to matter, they generally mediate a fifth force. In order for this fifth force to be consistent with existing constraints, it must be suppressed close to matter sources, e.g. through a non-linear screening mechanism. The focus of this talk will be shift-symmetric scalar-tensor theories...

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16. Experiments: Anomalies and open issues of the MICROSCOPE Space Testof the Weak Equivalence Principle

Anna Nobili (Università di Pisa, Dipartimento di Fisica (retired))

MICROSCOPE’s final results report no violation of the Weak Equivalence Principle (Universalityof Free Fall) for Pt and Ti test masses quantified by an E ̈otv ̈os parameter η∼10−15, an improvementby about two orders of magnitude over the best ground tests. The measurement is limited byrandom noise with 1ν√ frequency dependence attributed to thermal noise from internal dampingoccurring in the...

234. Experiments: Status of the GINGER project

Angela Di Virgilio

The measurements of the Earth rotation rate variations, certainly important for Earth science, are relevant also for fundamental physics investigation, as they contain general relativity terms, such as de Sitter and Lense Thirring, and they provide unique data to investigate Lorentz violations. Long term continuous operation and very high sensitivity are required, the limit to be reached to...

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27. Phenomenology: Characterizing Burst with Linear Memory Events with LIGO-Virgo-KAGRA and Pulsar Timing Array Observatories

Subhajit Dandapat (Tata Institute of Fundamental Research, Mumbai)

Close hyperbolic encounters of black holes (BHs) generate certain Burst With Memory (BWM) events in the frequency windows of the operational, planned, and proposed gravitational wave (GW) observatories. We provide details of our HyperbolicTD & GW_hyp packages that should allow both LIGO-Virgo-KAGRA (LVK) and Pulsar Timing Array (PTA) consortia to search for such BWM events in their respective...

23. Phenomenology: Computation of stochastic background from extreme mass ratio inspiral populations for LISA

Federico Pozzoli

Extreme mass ratio inspirals (EMRIs) are among the primary targets for the Laser Interferometer Space Antenna (LISA). The extreme mass ratios of these systems result in relatively weak GW signals, that can be individually resolved only for cosmologically nearby sources (up to 𝑧≈2). The incoherent piling up of the signal emitted by unresolved EMRIs generate a confusion noise, that can be...

223. Phenomenology: Information paradox and table-top experiments

Mojtaba Shahbazi (Tarbiat Modares University)

Black holes can be simulated by water in a tank or in general in analogue gravity models known as dumb holes. If one simulates the Hawking radiation in these models finds that the loss of information is equal to the loss of the momentum of the fluid over the dumb hole horizon. However, due to the steadiness of the horizon one expects that there is a missing momentum over the horizon. By...

81. Theory: Entanglement harvesting from conformal vacuums between two Unruh-DeWitt detectors moving along null paths

Subhajit Barman (Indian Institute of Technology Madras)

It is well-known that the (1+1) dimensional Schwarzschild and spatially flat FLRW spacetimes are conformally flat. This work examines entanglement harvesting from the conformal field vacuums in these spacetimes between two Unruh-DeWitt detectors, moving along outgoing null trajectories. In (1+1) dimensional Schwarzschild spacetime, we considered the Boulware and Unruh vacua for our...

235. Theory: Noncommutative Correction to Black Hole Entropy

Filip Požar

Noncommutative geometry is an established potential candidate for including quantum phenomena in gravitation. We outline the formalism of Hopf algebras and its connection to the algebra of infinitesimal diffeomorphisms. Using a Drinfeld twist we deform spacetime symmetries, algebra of vector fields and differential forms leading to a formulation of noncommutative Einstein equations. We study a...

237. Theory: Probing the Big Bang with Quantum Fields

Marc Schneider (SISSA)

The singularity theorems of Penrose and Hawking are based on geodesic incompleteness and predict the occurrence of classical singularities under rather general circumstances. In general relativity, these singularities represent absolute boundaries where space-time ends.
Physically, however, this criterion refers to the fate of point like classical test particles. We raise the question: What...