Periodic Reporting for period 1 - NewFunFiCO (Fundamental Fields and Compact Objects: new opportunities)
Berichtszeitraum: 2023-01-01 bis 2024-12-31
The celebrated detection of gravitational waves (GWs), the first observation of horizon scale structure of a black hole (BH) together with the developments in the field of numerical relativity, are allowing access to extreme (strong and dynamical) gravity configurations, both observationally and theoretically, making our time a golden epoch for studying extreme gravitational systems. In parallel, families of exotic but theoretically sound models of BHs and horizonless compact objects in the presence of new fundamental fields, or alternative theories of gravity have been constructed, to a large extent numerically.
This project creates a multi-connected team with different and complementary scientific expertises - on BHs, neutron stars and exotic compact objects -, their phenomenology - GWs, lensing and astrophysical environments - and the techniques necessary to extract the latter from the former for comparison with observations, including constructing and evolving solutions of non-standard compact objects with numerical methods, building GW libraries, lensing images and performing data/Bayesian analysis and parameter estimation.
This project creates a multi-connected team with different and complementary scientific expertises - on BHs, neutron stars and exotic compact objects -, their phenomenology - GWs, lensing and astrophysical environments - and the techniques necessary to extract the latter from the former for comparison with observations, including constructing and evolving solutions of non-standard compact objects with numerical methods, building GW libraries, lensing images and performing data/Bayesian analysis and parameter estimation.
Scientifically, in the first period of the action over 40 scientific papers were written including some impactful results. A full list of publications can be found here
https://ui.adsabs.harvard.edu/search/fq=%7B!type%3Daqp%20v%3D%24fq_database%7D&fq_database=(database%3Aastronomy%20OR%20database%3Aphysics)&p_=0&q=%20full%3A%22NewFunFiCO-101086251%22%20&sort=date%20desc%2C%20bibcode%20desc(öffnet in neuem Fenster)
Within the project, several international meetings were promoted. Within the first reporting period these include:
NewFunFiCO Kick-off Meeting
19th January 2023
The meeting was virtual, but it promised very interesting real work and synergies to come in the next four years!
Workshop on Fundamental Fields and Compact Objects: New Opportunities
4th - 6th October 2023
The aim of this 3-day workshop is to foster discussion and stimulate collaboration between researchers working on black holes and other astrophysical compact objects. It will also provide young researchers with a comprehensive introduction to the state of the art of the various central fields of research.
Amazonian Workshop on Gravity and analogue models
17th - 21st June 2024
The Amazonian Workshop on Gravity and Analogue Models is an introductory to mid-level meeting intended to be regularly held by the Graduate Program in Physics at the Pará University. Under the NewFunFiCO project it allowed the the interaction and transfer of knowledge amongst various nodes of the consortium.
VI Amazonian Symposium on Physics
18th - 22nd November 2024
The VI Amazonian Symposium on Physics is targeted for young researchers and graduate students in Physics, as well as for last-year undergraduate students, wishing to learn about Gravitation, from some of the world’s leading experts. Under the NewFunFiCO project it allowed the the interaction and transfer of knowledge amongst various nodes of the consortium.
https://ui.adsabs.harvard.edu/search/fq=%7B!type%3Daqp%20v%3D%24fq_database%7D&fq_database=(database%3Aastronomy%20OR%20database%3Aphysics)&p_=0&q=%20full%3A%22NewFunFiCO-101086251%22%20&sort=date%20desc%2C%20bibcode%20desc(öffnet in neuem Fenster)
Within the project, several international meetings were promoted. Within the first reporting period these include:
NewFunFiCO Kick-off Meeting
19th January 2023
The meeting was virtual, but it promised very interesting real work and synergies to come in the next four years!
Workshop on Fundamental Fields and Compact Objects: New Opportunities
4th - 6th October 2023
The aim of this 3-day workshop is to foster discussion and stimulate collaboration between researchers working on black holes and other astrophysical compact objects. It will also provide young researchers with a comprehensive introduction to the state of the art of the various central fields of research.
Amazonian Workshop on Gravity and analogue models
17th - 21st June 2024
The Amazonian Workshop on Gravity and Analogue Models is an introductory to mid-level meeting intended to be regularly held by the Graduate Program in Physics at the Pará University. Under the NewFunFiCO project it allowed the the interaction and transfer of knowledge amongst various nodes of the consortium.
VI Amazonian Symposium on Physics
18th - 22nd November 2024
The VI Amazonian Symposium on Physics is targeted for young researchers and graduate students in Physics, as well as for last-year undergraduate students, wishing to learn about Gravitation, from some of the world’s leading experts. Under the NewFunFiCO project it allowed the the interaction and transfer of knowledge amongst various nodes of the consortium.
Some examples of works beyond the state of the art are:
Bondi-Hoyle-Lyttleton accretion onto a rotating black hole with ultralight scalar hair
A. Cruz-Osorio, L. Rezzolla, F. D. Lora-Clavijo, J. A. Font, C. Herdeiro, E. Radu
JCAP 08 (2023) 057
e-Print: arXiv:2301.06564[gr-gq]
In this work, we present a numerical study of relativistic Bondi-Hoyle-Lyttleton (BHL) accretion onto an asymptotically flat black hole with synchronized hair. The hair is sourced by an ultralight, complex scalar field, minimally coupled to Einstein's gravity. Our simulations consider a supersonic flow parametrized by the asymptotic values of the fluid quantities and a sample of hairy black holes with different masses, angular momenta, and amount of scalar hair. For all models, steady-state BHL accretion solutions are attained that are characterized by the presence of a shock-cone and a stagnation point downstream. For the models of the sample with the largest component of scalar field, the shock-cone envelops fully the black hole, transitioning into a bow-shock, and the stagnation points move further away downstream. Analytical expressions for the mass accretion rates are obtained after fitting the numerical results, which can be used to analyze black-hole formation scenarios in the presence of ultralight scalar fields. The formation of a shock-cone leads to regions where sound waves can be trapped and resonant oscillations excited. We measure the frequencies of such quasi-periodic oscillations and point out a possible association with quasi-periodic oscillations in the X-ray light curve of Sgr A* and microquasars.
Two spinning black holes balanced by their synchronized scalar hair
Carlos Herdeiro, Eugen Radu
Phys. Rev. Lett. 131 (2023) 121401
e-Print: arXiv:2305.15467 [gr-gq]
General relativity minimally coupled to a massive, free, complex scalar field, is shown to allow asymptotically flat solutions, nonsingular on and outside the event horizon, describing two spinning black holes (2sBHs) in equilibrium, with coaxial, aligned angular momenta. The 2sBHs configurations bifurcate from solutions describing dipolar spinning boson stars. The BHs emerge at equilibrium points diagnosed by a test particle analysis and illustrated by a Newtonian analog. The individual BH “charges” are mass and angular momentum only. Equilibrium is due to the scalar environment, acting as a (compact) dipolar field, providing a lift against their mutual attraction, making the 2sBHs (h)airborne. We explore the 2sBHs domain of solutions and its main features.
Precessing binary black holes as engines of electromagnetic helicity
N. Sanchis-Gual, A. del Rio
Phys. Rev. D 108 (2023) 044052
e-Print: arXiv:2303.15534[gr-gq]
We show that binary black hole mergers with precessing evolution can potentially excite photons from the quantum vacuum in such a way that total helicity is not preserved in the process. Helicity violation is allowed by quantum fluctuations that spoil the electric-magnetic duality symmetry of the classical Maxwell theory without charges. We show here that precessing binary black hole systems in astrophysics generate a flux of circularly polarized gravitational waves which, in turn, provides the required helical background that triggers this quantum effect. Solving the fully nonlinear Einstein’s equations with numerical relativity we explore the parameter space of binary systems and extract the detailed dependence of the quantum effect with the spins of the two black holes. We also introduce a set of diagrammatic techniques that allows us to predict when a binary black hole merger can or cannot emit circularly polarized gravitational radiation, based on mirror-symmetry considerations. This framework allows to understand and to interpret correctly the numerical results, and to predict the outcomes in potentially interesting astrophysical systems.
Bondi-Hoyle-Lyttleton accretion onto a rotating black hole with ultralight scalar hair
A. Cruz-Osorio, L. Rezzolla, F. D. Lora-Clavijo, J. A. Font, C. Herdeiro, E. Radu
JCAP 08 (2023) 057
e-Print: arXiv:2301.06564[gr-gq]
In this work, we present a numerical study of relativistic Bondi-Hoyle-Lyttleton (BHL) accretion onto an asymptotically flat black hole with synchronized hair. The hair is sourced by an ultralight, complex scalar field, minimally coupled to Einstein's gravity. Our simulations consider a supersonic flow parametrized by the asymptotic values of the fluid quantities and a sample of hairy black holes with different masses, angular momenta, and amount of scalar hair. For all models, steady-state BHL accretion solutions are attained that are characterized by the presence of a shock-cone and a stagnation point downstream. For the models of the sample with the largest component of scalar field, the shock-cone envelops fully the black hole, transitioning into a bow-shock, and the stagnation points move further away downstream. Analytical expressions for the mass accretion rates are obtained after fitting the numerical results, which can be used to analyze black-hole formation scenarios in the presence of ultralight scalar fields. The formation of a shock-cone leads to regions where sound waves can be trapped and resonant oscillations excited. We measure the frequencies of such quasi-periodic oscillations and point out a possible association with quasi-periodic oscillations in the X-ray light curve of Sgr A* and microquasars.
Two spinning black holes balanced by their synchronized scalar hair
Carlos Herdeiro, Eugen Radu
Phys. Rev. Lett. 131 (2023) 121401
e-Print: arXiv:2305.15467 [gr-gq]
General relativity minimally coupled to a massive, free, complex scalar field, is shown to allow asymptotically flat solutions, nonsingular on and outside the event horizon, describing two spinning black holes (2sBHs) in equilibrium, with coaxial, aligned angular momenta. The 2sBHs configurations bifurcate from solutions describing dipolar spinning boson stars. The BHs emerge at equilibrium points diagnosed by a test particle analysis and illustrated by a Newtonian analog. The individual BH “charges” are mass and angular momentum only. Equilibrium is due to the scalar environment, acting as a (compact) dipolar field, providing a lift against their mutual attraction, making the 2sBHs (h)airborne. We explore the 2sBHs domain of solutions and its main features.
Precessing binary black holes as engines of electromagnetic helicity
N. Sanchis-Gual, A. del Rio
Phys. Rev. D 108 (2023) 044052
e-Print: arXiv:2303.15534[gr-gq]
We show that binary black hole mergers with precessing evolution can potentially excite photons from the quantum vacuum in such a way that total helicity is not preserved in the process. Helicity violation is allowed by quantum fluctuations that spoil the electric-magnetic duality symmetry of the classical Maxwell theory without charges. We show here that precessing binary black hole systems in astrophysics generate a flux of circularly polarized gravitational waves which, in turn, provides the required helical background that triggers this quantum effect. Solving the fully nonlinear Einstein’s equations with numerical relativity we explore the parameter space of binary systems and extract the detailed dependence of the quantum effect with the spins of the two black holes. We also introduce a set of diagrammatic techniques that allows us to predict when a binary black hole merger can or cannot emit circularly polarized gravitational radiation, based on mirror-symmetry considerations. This framework allows to understand and to interpret correctly the numerical results, and to predict the outcomes in potentially interesting astrophysical systems.