Search

We derive the third subleading (N$^3$LO) corrections of the quadratic-in-spin sectors via the EFT of spinning objects in post-Newtonian (PN) gravity. These corrections consist of contributions from $4$ sectors for generic compact binaries, that enter at the fifth PN order. One of these contributions is due to a new tidal interaction, that is unique to the sectors with spin, and complements the first tidal interaction that also enters at this PN order in the simple point-mass sector. The evaluation of Feynman graphs is carried out in a generic dimension via advanced multi-loop methods, and gives rise to dimensional-regularization poles in conjunction with logarithms. At these higher-spin sectors the reduction of generalized Lagrangians entails redefinitions of the position beyond linear order. We provide here the most general Lagrangians and Hamiltonians. We then specify the latter to simplified configurations, and derive the consequent gauge-invariant relations among the binding energy, angular momentum, and frequency. We end with a derivation of all the scattering angles that correspond to an extension of our Hamiltonians to the scattering problem in the simplified aligned-spins configuration, as a guide to scattering-amplitudes studies., 57 pp, 1 figure; 25 ancillary files, including pdf of ~1000 visual graphs

We investigate the shadow, deflection angle, and the greybody bounding of a Schwarzschild-AdS/dS black hole in scale-dependent gravity. We used the EHT data to constrain the parameter $\epsilon$. We have found that within the $1\sigma$ level of uncertainty, $\epsilon M_0$ ranges at $10^{-11} - 10^{-16}$ orders of magnitude for Sgr. A*, and $10^{-11} - 10^{-17}$ for M87*. Using these parameters, we explored how the shadow radius behaves as perceived by a static observer. Using the known parameters for Sgr. A* and M87*, we found different shadow cast behavior near the cosmological horizon even if the same scaling parameters were used. We explored the deflection angle $\hat{\alpha}$ in the weak field limit for both massive and null particles, in addition to the effect of finite distances using the non-asymptotically flat version of the Gauss-Bonnet theorem. We have found that the $\hat{\alpha}$ strongly depends on massive particles. Tests on $\epsilon$'s effect using Sgr. A* is only along points of low impact parameters. For M87*, only the scaled BH in AdS type can be tested at high impact parameters at the expense of very low value for $\hat{\alpha}$. We study the rigorous bound on the greybody factor for scalar field emitted from black holes in the theory and show the bound on the transmission probability. The effects of the scale-dependent gravity on the greybody factors are investigated, and the results indicate that the bound on the greybody factor in this case is less than the bound for the Schwarzschild black hole., Comment: 16 pages, 7 figures

The space-time metric AdS will be determined and based on it the cosmological constant will be calculated as a function of the radius of the space AdS, using this cosmological constant the Einstein equations will be solved in order to find a metric based on from the radial coordinate of the event horizon, then some thermodynamic properties of black holes in spacetime AdS such as temperature, area and entropy will be calculated., Se determinará la métrica del espacio-tiempo AdS y en base a ella se calculará la cosntante cosmológica en función del radio del espacio AdS, usando esta constante cosmológica se resolverán las ecuaciones de Einstein con el objetivo de encontrar una métrica en función de la coordenada radial del horizonte de eventos, luego se calcularán algunas propiedades termodinámicas de los agujeros negros en el espacio-tiempo AdS como temperatura, área y entropía.

Context:TheGW-Universe Toolboxis a software package that simulates observations of the gravitational wave (GW) Universe with different types of GW detectors, including Earth-based and space-borne laser interferometers and pulsar timing arrays. It is accessible as a website, and can also be imported and run locally as a Python package.Methods:We employ the method used by theGW-Universe Toolboxto generate a synthetic catalogue of detection of stellar-mass binary black hole (BBH) mergers. As an example of its scientific application, we study how GW observations of BBHs can be used to constrain the merger rate as a function of redshift and masses. We study advanced LIGO (aLIGO) and theEinsteinTelescope (ET) as two representatives of the second and third generation GW observatories, respectively. We also simulate the observations from a detector that is half as sensitive as the ET at its nominal designed sensitivity, which represents an early phase of the ET. We used two methods to obtain the constraints on the source population properties from the catalogues: the first uses a parameteric differential merger rate model and applies a Bayesian inference on the parameters; the other is non-parameteric and uses weighted Kernel density estimators.Results:Our results show the overwhelming advantages of the third generation detector over those of the second generation for the study of BBH population properties, especially at redshifts higher than ∼2, where the merger rate is believed to peak. With the simulated aLIGO catalogue, the parameteric Bayesian method can still give some constraints on the merger rate density and mass function beyond its detecting horizon, while the non-parametric method loses the constraining ability completely there. The difference is due to the extra information placed by assuming a specific parameterisation of the population model in the Bayesian method. In the non-parameteric method, no assumption of the general shape of the merger rate density and mass function are placed, not even the assumption of its smoothness. These two methods represent the two extreme situations of general population reconstruction. We also find that, despite the numbers of detected events of the half ET can easily be compatible with full ET after a longer observation duration, and the catalogue from the full ET can still give much better constraints on the population properties due to its smaller uncertainties on the physical parameters of the GW events.

Motivated by the results of Anastasiou et al., we consider the convolutional double copy for BRST and anti-BRST covariant formulations of gravitational and gauge theories in more detail. We give a general BRST and anti-BRST invariant formulation of linearised $\mathcal{N}=0$ supergravity using superspace methods and show how this may be obtained from the square of linearised Yang-Mills theories. We demonstrate this relation for the Schwarzschild black hole and the ten-dimensional black string solution as two concrete examples., Comment: 35 pages

In holography, the IR behavior of a quantum system at nonzero density is described by the near horizon geometry of an extremal charged black hole. It is commonly believed that for systems on $S^3$, this near horizon geometry is $AdS_2\times S^3 $. We show that this is not the case: generic static, nonspherical perturbations of $AdS_2\times S^3 $ blow up at the horizon, showing that it is not a stable IR fixed point. We then construct a new near horizon geometry which is invariant under only $SO(3)$ (and not $SO(4)$) symmetry and show that it is stable to $SO(3)$-preserving perturbations (but not in general). We also show that an open set of nonextremal, $SO(3)$-invariant charged black holes develop this new near horizon geometry in the limit $T \to 0$. Our new IR geometry still has $AdS_2$ symmetry, but it is warped over a deformed sphere. We also construct many other near horizon geometries, including some with no rotational symmetries, but expect them all to be unstable IR fixed points., 44 pages, 13 figures

We construct novel black strings that are neither time-translation invariant, nor axisymmetric, nor translationally invariant in the string direction, but nevertheless have a helical Killing vector field. These solutions branch from the superradiant instability of $D=6$ Myers-Perry black strings with equal angular momenta. We coin these solutions as {\it black resonator strings} and we find that they have more entropy than Myers-Perry black strings for the energies and angular momenta where both solutions coexist. We also construct Kaluza-Klein geons, which share the symmetries of black resonator strings, but are horizonless. Unlike in other superradiant systems, Kaluza-Klein geons are not the horizonless limit of black resonator strings and are instead entirely separate solutions., Comment: 35 pages, 8 figures

We investigate the geometry near the horizon of a generic, four-dimensional extremal black hole. When the cosmological constant is negative, we show that (in almost all cases) tidal forces diverge as one crosses the horizon, and this singularity is stronger for larger black holes. In particular, this applies to generic nonspherical black holes, such as those satisfying inhomogeneous boundary conditions. Nevertheless, all scalar curvature invariants remain finite. Moreover, we show that nonextremal black holes have tidal forces that diverge in the extremal limit. Holographically, this singularity is reflected in anomalous scaling of the specific heat with temperature. Similar (albeit weaker) effects are present when the cosmological constant is positive, but not when it vanishes., 41 pages, 7 figures, v3: accepted for publication in JHEP

We solve the Wheeler-DeWitt equation for the planar AdS-Schwarzschild interior in a minisuperspace approximation involving the volume and spatial anisotropy of the interior. A Gaussian wavepacket is constructed that is peaked on the classical interior solution. Simple observables are computed using this wavepacket, demonstrating the freedom to a choose a relational notion of `clock' in the interior and characterizing the approach to the spacelike singularity. The Wheeler-DeWitt equation may be extended out through the horizon, where it describes the holographic renormalization group flow of the black hole exterior. This amounts to the Hamilton-Jacobi evolution of the metric component $g_{tt}$ from positive interior values to negative exterior values. The interior Gaussian wavepacket is shown to evolve into the Lorentizan partition function of the boundary conformal field theory over a microcanonical energy window., 31 pages. 1 figure. v2 minor improvements. v3 minor improvements

Strong correlations exist between supermassive black holes (SMBHs) and their host galaxies. These correlations suggest a missing component in our current understanding: the role of energy cascade in SMBH-bulge coevolution. In this picture, energy is continuously cascaded from bulge scale $r_b$ down to the BH scale (Schwarzschild radius \(r_s\)). Energy cascade has a scale-independent, but decreasing rate \(\varepsilon_b(t)\approx \sigma_b^3/r_b\)due to the cooling of baryonic component, where \(\sigma_b\)is bulge velocity dispersion. The bulge mass-size (\(M_b\)-\(r_b\)) relation can be expressed as \(M_b \propto \varepsilon_b^{2/3}r_b^{5/3}G^{-1}\), or a bulge density-size relation\(\rho_b \propto \varepsilon_b^{2/3}r_b^{-4/3}G^{-1}\), with \(\varepsilon_b \approx a^{-5/2}\times 10^{-4}m^2/s^3\), as confirmed by the galaxy survey, where \(a\)is the scale factor and \(G\)is the gravitational constant. Intermediate length scales can be defined based on the dominant physics on that scale, i.e. the BH sphere of influence \(r_B\), radiation scale \(r_p\), and dissipation scale \(r_x\). For SMBH with a mass \(M_B\), bolometric luminosity \(L_B\), energy cascade leads to a "cascade" force that must be balanced by the BH radiation force in its early life, i.e. \(L_B/c=M_B \varepsilon_b /\sigma_p\), where \(c\)is light speed and \(\sigma_p\)is the velocity dispersion on scale \(r_p\). Since \(\varepsilon_b\)is much larger in the early universe, BH accretion can be super-Eddington with \(L_B\)exceeds the Eddington limit. By introducing two dimensionless parameters \(\gamma={L_B}/(M_B\varepsilon_b)\)and \(\eta=({GL_B}/{c^5})^{{1}/{4}}\), the distribution and evolution of SMBHs can all be mapped onto the \(\gamma\)-\(\eta\)plane. By setting \(r_s \le r_p\le r_B\), the upper limit of distribution is found to be \(L_B \propto (\varepsilon_b M_B)^{4/5}G^{-1/5}c\). The lower limit is found to be \(L_B \propto (\varepsilon_b M_B)^{4/3}G^{1/3}c^{-5/3}\). Quasars tend to approach the upper limit, while dormant SMBHs (Sgr A* and M31) tend to approach the lower limit. A three stage mathematical model is proposed for SMBH evolution involving co-evolution, transitional, and dormant stages, respectively. Models are finally compared against the BH accretion history from quasar luminosity function from 2dF Redshify Survey, local galaxy and SMBHs data, and high redshift quasars from SDSS DR7 and CFHQS surveys. Condensed slides for all applications "Cascade Theory for Turbulence, Dark Matter, and Supermassive Black Holes" Applicationsof cascade and statistical theory for dark matter and SMBH evolution: Dark matter particle mass ,size, and properties from energy cascade in dark matter flow: 1) arxiv 2) zenodo slides Origin of MOND acceleration &deep-MOND fromacceleration fluctuation &energy cascade: 1) arxiv 2) zenodo slides The baryonic-to-halo mass relation from mass and energy cascade in dark matter flow: 1) arxiv 2) zenodo slides Universal scaling laws and density slope for dark matter halos from rotation curves: 1) arxiv 2) zenodo slides A unified theory for dark matter halo mass function and density profile: 1) arxiv 2) zenodo slides Energy cascade for distribution and evolution of supermassive black holes (SMBHs): 2) zenodo slides The two relevant datasets and accompanying presentation can be found at: Dark matter flow dataset Part I: Halo-based statistics from cosmological N-body simulation Dark matter flow dataset Part II: Correlation-based statistics from cosmological N-body simulation. A comparative study of Dark matter flow & hydrodynamic turbulence and its applications The same dataset also available on Github at: Github: dark_matter_flow_datasetandzenodo at:Dark matter flow dataset from cosmological N-body simulation. Cascade and statistical theory developed by these dataset: Inverse mass cascade in dark matter flow and effects on halo mass functions: 1)arxiv2)zenodo slides Inverse mass cascade and effects on halo deformation, energy, size, and density profiles: 1) arxiv 2) zenodo slides Inverse energy cascade indark matter flow and effects of halo shape: 1) arxiv 2) zenodo slides The mean flow, velocity dispersion, energy transfer and evolution ofdark matter halos: 1) arxiv 2) zenodo slides Two-body collapse model and generalized stable clustering hypothesis for pairwise velocity1) arxiv 2) zenodo slides Energy, momentum, spin parameter in dark matter flow and integral constants of motion: 1) arxiv 2) zenodo slides Maximum entropy distributions of velocity, speed, and energy indark matter flow: 1) arxiv 2) zenodo slides Halo mass functions from maximum entropy distributions in dark matter flow: 1) arxiv 2) zenodo slides The statistical theory of dark matter flow for velocity, density, and potential fields: 1) arxiv 2) zenodo slides High order kinematic and dynamic relations for velocity correlations in dark matter flow: 1) arxiv 2) zenodo slides Evolution ofdensity andvelocity distributions and two-thirds law for pairwise velocity: 1) arxiv 2) zenodo slides

In this paper, we explore the gravitational collapse of matter (dust) under the effect of zero-point length $l_0$. During the gravitational collapse, we have neglected the backreaction effect of the pre-Hawking radiation (in the sense that it is small effect and cannot prevent the formation of apparent horizon), then we recast the internal metric of a collapsing star as a closed FRW universe for any spherically symmetric case and, finally, we obtain the minimal value for the scale factor meaning that the particles never hit the singularity. We argue that the object emerging at the end of the gravitational collapse can be interpreted as Planck stars (black hole core) hidden inside the event horizon of the black hole with radius proportional to $(GMl_0^{2}/c^2)^{1/3}$. Quite interestingly, we found the same result for radius of the Planck star using a free falling observer point of view. In addition, we pointed out a correspondence between the modified Friedmann's equations in loop quantum gravity and the modified Friedmann's equation in string T-duality. In the end, we discuss two possibilities regarding the final stage of the black hole. The first possibility is that we end up with a Planck-size black hole remnants. The second possibility is that the inner core can be unstable and, due to the quantum tunnelling effect, the spacetime can undergo a black hole-to-white hole transition (a bouncing Planck star)., Comment: 9 pages, no figures. Published in Universe https://www.mdpi.com/2218-1997/9/1/41

We present a case for significantly enhancing the utility and efficiency of the ngEHT by incorporating an additional 86 GHz observing band. In contrast to 230 or 345 GHz, weather conditions at the ngEHT sites are reliably good enough for 86 GHz to enable year-round observations. Multi-frequency imaging that incorporates 86 GHz observations would sufficiently augment the ($u,v$) coverage at 230 and 345 GHz to permit detection of the M87 jet structure without requiring EHT stations to join the array. The general calibration and sensitivity of the ngEHT would also be enhanced by leveraging frequency phase transfer techniques, whereby simultaneous observations at 86 GHz and higher-frequency bands have the potential to increase the effective coherence times from a few seconds to tens of minutes. When observation at the higher frequencies is not possible, there are opportunities for standalone 86 GHz science, such as studies of black hole jets and spectral lines. Finally, the addition of 86 GHz capabilities to the ngEHT would enable it to integrate into a community of other VLBI facilities $-$ such as the GMVA and ngVLA $-$ that are expected to operate at 86 GHz but not at the higher ngEHT observing frequencies., Comment: 23 pages, 10 figures

We do a systematic search of supergravity solutions that, via the AdS5/CFT4 correspondence, are dual to thermal states in $$ \mathcal{N} $$ N = 4 SYM at finite chemical potential. These solutions dominate the microcanonical ensemble and are required to ultimately reproduce the microscopic entropy of AdS black holes. Using a mix of analytical and numerical methods, we construct and study static charged hairy solitonic and black hole solutions with global AdS5 asymptotics. They are constructed in two distinct consistent truncations of five dimensional gauged supergravity (and can thus be uplifted to asymptotically AdS5×S5 solutions of type IIB supergravity). In the “single charge” truncation which consists of one charged scalar field, hairy black holes exist above a critical charge and merge with the known Behrndt-Cvetič-Sabra (BCS) black holes along a curve determined by the onset of superradiance in the latter family. The lowest mass hairy black hole is a singular zero entropy soliton. In the “two charge” truncation which consists of a two equal charged scalar fields, hairy black holes exist for all charges and merge with the known BCS black holes along their superradiant onset curve. The lowest mass hairy black hole is a smooth supersymmetric zero entropy soliton. Together with the known phases of the truncation with three equal charges, our findings permit a good understanding of the full phase space of SYM thermal states with three arbitrary chemical potentials.

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 for quantum matter cores at the centre of rotating black holes with integrable singularities and no Cauchy horizon., Journal of High Energy Physics, 2023 (5), ISSN:1126-6708, ISSN:1029-8479

We construct a cohomogeneity-1 helical black string in six-dimensional Einstein gravity. The helical solution branches from the onset of the gravitational superradiant instability of the equal-spinning Myers-Perry black string. The isometry group of the helical black string is $\mathbb{R}_T \times U(1)_Z \times SU(2)$, where the first two are helical isometries generated by linear combinations of time translation, shifts along the string, and rotation, each of which is individually broken by the superradiant instability. The helical black string is stationary, non-axisymmetric, and has nonzero horizon velocity despite the absence of momentum in the string direction. The entropy of the helical black string is higher than that of the Myers-Perry black string, but lower than cohomogeneity-2 ``black resonator strings'' (recently found) when the solutions overlap in the microcanonical ensemble. The entropy of the helical black string approaches zero when the horizon velocity along the string reaches its maximum given by the speed of light. Nevertheless, we find no evidence for the existence of regular horizonless solutions in this limit., Comment: 57 pages, 9 figures

Full list of authors: Amaro-Seoane, Pau; Andrews, Jeff; Sedda, Manuel Arca; Askar, Abbas.; Baghi, Quentin; Balasov, Razvan; Bartos, Imre; Bavera, Simone S.; Bellovary, Jillian; Berry, Christopher P. L.; Berti, Emanuele; Bianchi, Stefano; Blecha, Laura; Blondin, Stephane; Bogdanovic, Tamara; Boissier, Samuel; Bonetti, Matteo; Bonoli, Silvia; Bortolas, Elisa; Breivik, Katelyn; Capelo, Pedro R.; Caramete, Laurentiu; Cattorini, Federico; Charisi, Maria; Chaty, Sylvain; Chen, Xian; Chruslinska, Martyna; Chua, Alvin J. K.; Church, Ross; Colpi, Monica; D'Orazio, Daniel; Danielski, Camilla; Davies, Melvyn B.; Dayal, Pratika; De Rosa, Alessandra; Derdzinski, Andrea; Destounis, Kyriakos; Dotti, Massimo; Dutan, Ioana; Dvorkin, Irina; Fabj, Gaia; Foglizzo, Thierry; Ford, Saavik; Fouvry, Jean-Baptiste; Franchini, Alessia; Fragos, Tassos; Fryer, Chris; Gaspari, Massimo; Gerosa, Davide; Graziani, Luca; Groot, Paul; Habouzit, Melanie; Haggard, Daryl; Haiman, Zoltan; Han, Wen-Biao; Istrate, Alina; Johansson, Peter H.; Khan, Fazeel Mahmood; Kimpson, Tomas; Kokkotas, Kostas; Kong, Albert; Korol, Valeriya; Kremer, Kyle; Kupfer, Thomas; Lamberts, Astrid; Larson, Shane; Lau, Mike; Liu, Dongliang; Lloyd-Ronning, Nicole; Lodato, Giuseppe; Lupi, Alessandro; Ma, Chung-Pei; Maccarone, Tomas; Mandel, Ilya; Mangiagli, Alberto; Mapelli, Michela; Mathis, Stephane; Mayer, Lucio; McGee, Sean; McKernan, Berry; Miller, M. Coleman; Mota, David F.; Mumpower, Matthew; Nasim, Syeda S.; Nelemans, Gijs; Noble, Scott; Pacucci, Fabio; Panessa, Francesca; Paschalidis, Vasileios; Pfister, Hugo; Porquet, Delphine; Quenby, John; Ricarte, Angelo; Roepke, Friedrich K.; Regan, John; Rosswog, Stephan; Ruiter, Ashley; Ruiz, Milton; Runnoe, Jessie; Schneider, Raffaella; Schnittman, Jeremy; Secunda, Amy; Sesana, Alberto; Seto, Naoki; Shao, Lijing; Shapiro, Stuart; Sopuerta, Carlos; Stone, Nicholas C.; Suvorov, Arthur; Tamanini, Nicola; Tamfal, Tomas; Tauris, Thomas; Temmink, Karel; Tomsick, John; Toonen, Silvia; Torres-Orjuela, Alejandro; Toscani, Martina; Tsokaros, Antonios; Unal, Caner; Vazquez-Aceves, Veronica; Valiante, Rosa; van Putten, Maurice; van Roestel, Jan; Vignali, Christian; Volonteri, Marta; Wu, Kinwah; Younsi, Ziri; Yu, Shenghua; Zane, Silvia; Zwick, Lorenz; Antonini, Fabio; Baibhav, Vishal; Barausse, Enrico; Bonilla Rivera, Alexander; Branchesi, Marica; Branduardi-Raymont, Graziella; Burdge, Kevin; Chakraborty, Srija; Cuadra, Jorge; Dage, Kristen; Davis, Benjamin; de Mink, Selma E.; Decarli, Roberto; Doneva, Daniela; Escoffier, Stephanie; Gandhi, Poshak; Haardt, Francesco; Lousto, Carlos O.; Nissanke, Samaya; Nordhaus, Jason; O'Shaughnessy, Richard; Portegies Zwart, Simon; Pound, Adam; Schussler, Fabian; Sergijenko, Olga; Spallicci, Alessandro; Vernieri, Daniele; Vigna-Gomez, Alejandro.-- This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/., The Laser Interferometer Space Antenna (LISA) will be a transformative experiment for gravitational wave astronomy, and, as such, it will offer unique opportunities to address many key astrophysical questions in a completely novel way. The synergy with ground-based and space-born instruments in the electromagnetic domain, by enabling multi-messenger observations, will add further to the discovery potential of LISA. The next decade is crucial to prepare the astrophysical community for LISA’s first observations. This review outlines the extensive landscape of astrophysical theory, numerical simulations, and astronomical observations that are instrumental for modeling and interpreting the upcoming LISA datastream. To this aim, the current knowledge in three main source classes for LISA is reviewed; ultra-compact stellar-mass binaries, massive black hole binaries, and extreme or interme-diate mass ratio inspirals. The relevant astrophysical processes and the established modeling techniques are summarized. Likewise, open issues and gaps in our understanding of these sources are highlighted, along with an indication of how LISA could help making progress in the different areas. New research avenues that LISA itself, or its joint exploitation with upcoming studies in the electromagnetic domain, will enable, are also illustrated. Improvements in modeling and analysis approaches, such as the combination of numerical simulations and modern data science techniques, are discussed. This review is intended to be a starting point for using LISA as a new discovery tool for understanding our Universe. © The Author(s) 2023, corrected publication 2023., P. Dayal acknowledges support from the European Research council (ERC-717001) and from the Netherlands Research Council NWO (016.VIDI.189.162). P.H. Johansson acknowledges the support from the European Research Council (ERC-818930). S. Toonen acknowledges support from the Netherlands Research Council NWO (VENI 639.041.645 Grants) C. Unal is supported by European Structural and Investment Funds and the Czech Ministry of Education, Youth and Sports (Project CoGraDS - CZ.02.1.01/0.0/0.0/15_003/0000437). S. Chaty acknowledges the LabEx UnivEarthS for the funding of Interface project I10 “From binary evolution towards merging of compact objects”. A. De Rosa acknowledges financial contribution from the agreement ASI-INAF n.2017-14-H.O E. Berti is supported by NSF Grants No. PHY-1912550 and AST-2006538, NASA ATP Grants No. 17-ATP17-0225 and 19-ATP19-0051, NSF-XSEDE Grant No. PHY-090003, and NSF Grant PHY-20043. D. Gerosa is supported by European Union’s H2020 ERC Starting Grant No. 945155–GWmining, Leverhulme Trust Grant No. RPG-2019-350 and Royal Society Grant No. RGS-R2-202004. T. Bogdanovic acknowledges support by the NASA award No. 80NSSC19K0319 and by the NSF award AST-1908042. D. Porquet acknowledges funding support from CNES. C. Danielski acknowledges financial support from the State Agency for Research of the Spanish MCIU through the “Center of Excellence Severo Ochoa” award to the Instituto de Astrofísica de Andalucía (SEV-2017-0709) B.L. Davis acknowledges support from Tamkeen under the NYU Abu Dhabi Research Institute Grant CAP3. F. Pacucci acknowledges support from a Clay Fellowship by the SAO and from the Black Hole Initiative, which is funded by grants from the John Templeton Foundation and the Gordon and Betty Moore Foundation. A.J. Ruiter acknowledges support from the Australian Research Council Future Fellowship Grant FT170100243. V. Paschalidis is supported by NSF Grant PHY-1912619 and NASA Grant 80NSSC20K1542 to the University of Arizona, and NSF-XSEDE Grant TG-PHY190020. D. Haggard acknowledges support from the NSERC Discovery Grant and Canada Research Chairs programs, and the Bob Wares Science Innovation Prospectors Fund. M. Toscani acknowledges European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie Grant Agreement No. 823823 (RISE DUSTBUSTERS project) and COST Action CA16104 - Gravitational waves, black holes and fundamental physics, supported by COST (European Cooperation in Science and Technology). M. Chruslinska, A. Istrate and G. Nelemans acknowledge support from Netherlands Research Council NWO. T. Fragos and S. Bavera acknowledge support from a Swiss National Science Foundation Professorship Grant (project numbers PP00P2_176868 and PP00P2_211006)., With funding from the Spanish government through the "Severo Ochoa Centre of Excellence" accreditation (CEX2021-001131-S).

This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/)., In the past few years, the Event Horizon Telescope (EHT) has provided the first-ever event horizon-scale images of the supermassive black holes (BHs) M87∗ and Sagittarius A∗ (Sgr A∗ ). The next-generation EHT project is an extension of the EHT array that promises larger angular resolution and higher sensitivity to the dim, extended flux around the central ring-like structure, possibly connecting the accretion flow and the jet. The ngEHT Analysis Challenges aim to understand the science extractability from synthetic images and movies to inform the ngEHT array design and analysis algorithm development. In this work, we compare the accretion flow structure and dynamics in numerical fluid simulations that specifically target M87∗ and Sgr A∗, and were used to construct the source models in the challenge set. We consider (1) a steady-state axisymmetric radiatively inefficient accretion flow model with a time-dependent shearing hotspot, (2) two time-dependent single fluid general relativistic magnetohydrodynamic (GRMHD) simulations from the H-AMR code, (3) a two-temperature GRMHD simulation from the BHAC code, and (4) a two-temperature radiative GRMHD simulation from the KORAL code. We find that the different models exhibit remarkably similar temporal and spatial properties, except for the electron temperature, since radiative losses substantially cool down electrons near the BH and the jet sheath, signaling the importance of radiative cooling even for slowly accreting BHs such as M87∗. We restrict ourselves to standard torus accretion flows, and leave larger explorations of alternate accretion models to future work. © 2023 by the authors. Licensee MDPI, Basel, Switzerland., We thank the National Science Foundation (AST-1716536, AST-1935980 and AST-2034306) and the Gordon and Betty Moore Foundation (GBMF-10423) for financially supporting this work. This work was supported in part by the Black Hole Initiative, which is funded by grants from the John Templeton Foundation (JTF-61497) and the Gordon and Betty Moore Foundation (GBMF-8273) to Harvard University. K.C. is also supported in part by the Black Hole PIRE program (NSF grant OISE-1743747). R.E. acknowledges the support by the Institute for Theory and Computation at the Center for Astrophysics as well as grant numbers 21-atp21-0077, NSF AST-1816420, and HST-GO-16173.001-A for very generous supports. H.M. received financial support for this research from the International Max Planck Research School (IMPRS) for Astronomy and Astrophysics at the Universities of Bonn and Cologne. This research is supported by the DFG research grant “Jet physics on horizon scales and beyond” (Grant No. FR 4069/2-1), the ERC synergy grant “BlackHoleCam: Imaging the Event Horizon of Black Holes” (Grant No. 610058), and ERC advanced grant “JETSET: Launching, propagation and emission of relativistic jets from binary mergers and across mass scales” (Grant No. 884631). J.K. acknowledges funding by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany´s Excellence Strategy—EXC 2094—390783311. Y.M. is supported by the National Natural Science Foundation of China (No. 12273022) and the Shanghai pilot program of international scientists for basic research (No. 22JC1410600)., With funding from the Spanish government through the "Severo Ochoa Centre of Excellence" accreditation (CEX2021-001131-S).

We construct the holographic duals to a large $N$, strongly coupled $\mathcal{N}=4$ super Yang-Mills conformal field theory defined on a four-dimensional de Sitter-Schwarzschild background. There are two distinct five-dimensional bulk solutions. One, named the black tunnel, is static and possesses two disconnected horizons. The other, the black hammock, contains only one horizon in the bulk. The hammock horizon is not a Killing horizon, and hence possesses interesting properties, such as non-vanishing expansion and shear, as well as allowing classical flow along it. The DeTurck method was used in order to attain the black tunnel solutions, whilst the black hammocks were found in Bondi-Sachs gauge., Comment: 45 pages, 13 figures

The main objective of this paper is to understand the entropy of the mass/energy objects (Signals Information SI) wave functions. As the wave functions are complex, we computed a complex entropy that is equivalent to the Shannon one to calculate the deformation due to the space and time summation or the interferences or what we have demonstrated to be the Gravity effect. The imaginary part of this complex entropy has been shown to describe the spacetime curvature. In this paper we will prove that the real part of this entropy is the thermodynamical entropy effect one defined by the Hawking Radiation.

Supermassive black holes (SMBHs), residing in the nuclei of most galaxies, are capable of imparting extreme amounts of energy to their surroundings. Observations indicate the presence of collimated, relativistic jets as well as powerful, multiphase winds emanating from these active galactic nuclei (AGN). Whilst the clearest observational signatures of AGN jet feedback are found in galaxy clusters, there is growing evidence that these jets are, in fact, largely ubiquitous. Indeed, AGN jets have now been detected in a wide variety of galaxy contexts including dwarfs, Seyferts and ellipticals. Looking towards the future, observational facilities such as JWST, SKA and Athena will greatly expand our understanding of AGN physics by facilitating investigations of SMBH jet feedback at earlier times, lower luminosities and with higher spatial and spectral resolution. Additionally, the LISA mission will expand the field of multimessenger astronomy to the low-frequency range, detecting gravitational waves from the coalescence of SMBHs all the way back to cosmic dawn. Exploring the coupled evolution of AGN and their host galaxies is a highly non-linear, multiscale, problem and, thus, lends itself to exploration via numerical simulation techniques. For numerical simulations to provide firm theoretical predictions for, as well as accurately interpret the wealth of data from these next-generation facilities, however, it is vital that physically motivated models of AGN feedback are applied in realistic galaxy formation scenarios. In this thesis I present a novel numerical scheme to model SMBH spin-driven jet feedback in galaxy formation simulations. I then apply this model, first to simulations of isolated Seyfert galaxies and then to simulations of the major merger of gas-rich galaxies at cosmic noon, exploring how AGN jet feedback affects the properties and evolution of the host galaxies and the SMBHs themselves. In Chapter 1, I provide an overview of the relevant scientific concepts and historical events that set the scene for the work which is presented in the subsequent chapters. In Chapter 2, I introduce my model for black hole accretion through a (warped) α-disc and feedback in the form of a Blandford-Znajek jet and describe its numerical implementation. In the remainder of Chapter 2, I perform benchmarking of the model and explore the effects of AGN jet feedback on the central regions of a typical radio-loud Seyfert galaxy. Chapter 3 follows on directly from Chapter 2 and significantly expands the simulation suite presented therein. Using these simulations, I explore how varying the initial black hole spin magnitude and direction, the density of the medium into which the jet propagates and the rate at which gas is funnelled towards the black hole affect the evolution and properties of the jet-driven outflows. Then, in Chapter 4, I apply my spin-driven AGN jet model to black holes at the centres of gas-rich galaxies undergoing a major merger at z ≈ 2. With these simulations, I explore how the AGN jets affect the stellar component, the gaseous haloes of the galaxies and the dynamics of the merger. Additionally, I examine how the AGN jets self-regulate when subject to the extreme environments present in such mergers. Finally, in Chapter 5, I bring together the main conclusions from these three studies, before discussing some future prospects for work in this field., STFC studentship 2114057

Motivated by the quantum process of black hole evaporation and its implications for symmetries, we consider a qubit system with a random dynamics as a toy model of black hole. We compute its symmetry-resolved entropies and discuss its implications. We first consider the case where charges are conserved and compute the symmetry-resolved entropies. We derive a symmetry-resolved analogue of the Page curve. We then consider the case where symmetry is explicitly broken and charges are no longer conserved. It serves as a toy model for global symmetry breaking in black hole evaporation. Despite the simple framework, the symmetry-resolved entropies capture various interesting features during the analogous process of black hole evaporation in our qubit model., 7 pages, 4 figures

In this paper, we describe an extremely efficient method for computing the renormalized stress-energy tensor of a quantum scalar field in spherically-symmetric black hole spacetimes. The method applies to a scalar field with arbitrary field parameters. We demonstrate the utility of the method by computing the renormalized stress-energy tensor for a scalar field in the Schwarzschild black hole spacetime, applying our results to discuss the null energy condition and the semi-classical backreaction., 8 pages, 4 figures. Paper has been extended with further discussion and results added. Published in Physical Review D

A short time ago, I published an article about deceleration of the universe. It was especially based on entropy, and it explains how does matter work, produce free energy by using its own creation motion without external energy; also is about instant communication and jumping interstellar by imitating starting condition of matter called as big-bang as a side effect on itself that the same with faster than light expansion as creation motion and outer space motion are accepted together. In this work, it was performed some analysis of the some specific subjects such as deceleration, uncertainty, particle formation, black hole, gravitation, energy, mass and light speed for identical simulation computations of the entire universe as the most sensitive as possible being related that article. There are some informations about escaping from black holes, event horizon lengths, viscosity of free space, re-derivation of Planck constants and infrastructure of some basic laws of existence mathematically as matter is directly dependent of geometric rules. Also, some elements were given for the readers to solve some required constants as the most sensitive manner. As the constants are not enough in the name of engineering, also finally I found a working algorithm which reduces process number of the power series to process number of the quadratic equations like calculating a root of an integer as an irrational number by solving equation; so also it can be used to calculate trigonometric values in the best manner for simulations of the entire universe besides physical constants as irrational values. Also there are new informations about the pioneer anomaly, gamma ray burst and non-observational universe.

Class material, including final presentations, for the 2018/2019 Science Research Mentoring Program (SRMP), held at the Harvard-Smithsonian Center for Astrophysics

Active Galactic Nuclei (AGN) are growing supermassive black holes found at the centers of massive galaxies. My research involves gathering data by simulating the light emitted by AGN, and then plotting the simulated light in the form of light curves.

The mission here is to see if we can find bound states for tachyons in some gravitational environment. That could provide an explanation for the phenomena called Dark Matter. Starting with the standard Schwarzschild metric in General Relativity, which is for a static and spherically symmetric source, it appears unlikely that such localized orbits exist. In this work the usual assumption of isotropic pressure is replaced by a model that has different pressures in the radial and angular directions. This should be relevant to the study of neutrinos, especially if they are tachyons, in cosmological models. We do find an arrangement that allows bound orbits for tachyons in a galaxy. This is a qualitative breakthrough. Then we go on to estimate the numbers involved and find that we do have a fair quantitative fit to the experimental data on the Galaxy Rotation Curve. Additionally we are led to look in the neighborhood of a Black Hole and there we find novel orbits for tachyons., Comment: 21 pages

A foundational theorem due to Buchdahl states that, within General Relativity (GR), the maximum compactness $\mathcal{C}\equiv GM/(Rc^2)$ of a static, spherically symmetric, perfect fluid object of mass $M$ and radius $R$ is $\mathcal{C}=4/9$. As a corollary, there exists a compactness gap between perfect fluid stars and black holes (where $\mathcal{C}=1/2$). Here we generalize Buchdahl's result by introducing the most general equation of state for elastic matter with constant longitudinal wave speeds and apply it to compute the maximum compactness of regular, self-gravitating objects in GR. We show that: (i) the maximum compactness grows monotonically with the longitudinal wave speed; (ii) elastic matter can exceed Buchdahl's bound and reach the black hole compactness $\mathcal{C}=1/2$ continuously; (iii) however, imposing subluminal wave propagation lowers the maximum compactness bound to $\mathcal{C}\approx0.462$, which we conjecture to be the maximum compactness of \emph{any} static elastic object satisfying causality; (iv) imposing also radial stability further decreases the maximum compactness to $\mathcal{C}\approx 0.389$. Therefore, although anisotropies are often invoked as a mechanism for supporting horizonless ultracompact objects, we argue that the black hole compactness cannot be reached with physically reasonable matter within GR and that true black hole mimickers require either exotic matter or beyond-GR effects., Comment: v2: 4 pages, 4 figures; Version submitted to PRD: Major revision extending the class of elastic materials to describe rigid materials beyond spherical-symmetry. Bounds on the compactness modified accordingly but discussion qualitatively similar to the previous version

Astronomers use a wide range of telescopes to study the universe, tuning into different parts of the electromagnetic spectrum to explore diverse astrophysical phenomena. Our eyes are sensitive to light that has a wavelength of approximately 500 nanometres. This is the region in which traditional, so-called ‘optical’ astronomy is carried out with facilities such as the Southern African Large Telescope in Sutherland. The choice of wavelength and telescope depends on the physical properties of the astronomical source of interest, e.g. hot gas at billion-degree temperatures is best studied at shorter wavelengths like X-rays. The recently launched James Webb Space Telescope will revolutionise our view of the infrared universe with a sensitivity significantly surpassing that of the Hubble Space Telescope. Another critical aspect of a telescope is the sharpness with which it can make out small details in a distant object. In this Commentary, we discuss a global network of radio telescopes known as the Event Horizon Telescope (EHT), observing light with a wavelength of 1 millimetre (mm), synthesising a much larger, earth-sized virtual telescope to achieve the sharpest detail attainable in astronomy. The primary objective of the EHT is to make images of supermassive black holes, behemoths that lie at the centres of galaxies and possess masses that range from about a million to ten billion times the mass of our own Sun.

This Volume is a continuation of the first volume of the 8T.TheGrand Unified Theory of Physics.V2.6Inserts: (Pages 233-234) Certainties Elimination - Breakthrough pg-234.Similar tothe first volume, the second volume is written by the solely by Manor Ohad. The second volume contains three parts. Firstpart - Reflections on the open questions of the 8T. Second Part - Reflections on Quantumphenomena using Number theory.Thirdpart - Reflections on the 8T framework and the Beauty of the finallaws of Nature. The authorincluded a collection ofadditional proofs to the most famous problem in number theory. The counting begins with the second proof as the first already presented in the first volume, Page 96-99 in "Classics". The Purpose of This volume is to Eliminate Certainties.&nbsp

We study the waveforms of time signals produced by scalar perturbations in static hairy black holes, in which the perturbations can be governed by a double-peak effective potential. The inner potential peak would give rise to echoes, which provide a powerful tool to test the Kerr hypothesis. The waveforms are constructed in the time and frequency domains, and we find that the late-time waveforms are determined by the long-lived and sub-long-lived quasinormal modes, which are trapped in the potential valley and near the smaller peak, respectively. When the distance between the peaks is significantly larger than the width of the peaks, a train of decaying echo pulses is produced by the superposition of the long-lived and sub-long-lived modes. In certain cases, the echoes can vanish and then reappear. When the peaks are close enough, one detects far fewer echo signals and a following sinusoid tail, which is controlled by the long-lived or sub-long-lived mode and hence decays very slowly., Comment: 22 pages, 6 figures, 2 tables and references add

For a static and spherically symmetric black hole, a photon sphere is composed of circular null geodesics of fixed radius, and plays an important role in observing the black hole. Recently, in an Einstein-Maxwell-scalar model with a non-minimal coupling between the scalar and electromagnetic fields, a class of hairy black holes has been found to possess two unstable and one stable circular null geodesics on the equatorial plane, corresponding to three photon spheres outside the event horizon. In this paper, we study quasinormal modes of the scalar field, which are associated with these circular null geodesics, in the hairy black hole spacetime. In the eikonal regime with $l\gg1$, the real part of the quasinormal modes is determined by the angular velocity of the corresponding circular geodesics. The imaginary part of the quasinormal modes associated with the unstable circular null geodesics encodes the information about the Lyapunov exponent of the corresponding circular geodesics. Interestingly, we find long-lived and sub-long-lived modes, which are associated with the stable and one of the unstable circular null geodesics, respectively. Due to tunneling through potential barriers, the damping times of the long-lived and sub-long-lived modes can be exponentially and logarithmically large in terms of $l$, respectively., Comment: 25 pages, 4 figures, 1 table, references added

I was able to observe electromagnetic waves due to a peculiar occurrence that occurred while I exerted extreme eye strain. I replicated the approach using JavaScript, and later discovered that error-level analysis settings made it considerably faster and simpler to extract the spectrum of light that is ordinarily invisible. This method is known as photoelectromagnetic imagery, or PEMi. In terms of forensics, never will you be able to photoshop anything again unless you are an extreme master that can trick the direction light waves roam.

It is well known that the Euclidean black hole action has a boundary term at the horizon proportional to the area. I show that if the horizon is replaced by a stretched horizon with appropriate boundary conditions, a new boundary term appears, described by a Schwarzian action similar to the recently discovered boundary actions in "nearly anti-de Sitter" gravity., 8 pages; v2: 9 pages, extended explanation of boundary conditions, other minor changes, to appear in a special issue of Gen. Rel. Grav. in memory of Prof. Thanu Padmanabhan ("Paddy")

In recent works by Wu and Wang a class of explicit symplectic integrators in curved spacetimes was presented. Different splitting forms or appropriate choices of time-transformed Hamiltonians are determined based on specific Hamiltonian problems. As its application, we constructed a suitable explicit symplectic integrator for surveying the dynamics of test particles in a magnetized Reissner–Nordström spacetime. In addition to computational efficiency, the scheme exhibits good stability and high precision for long-term integration. From the global phase-space structure of Poincaré sections, the extent of chaos can be strengthened when energy E, magnetic parameter B, or the charge q become larger. On the contrary, the occurrence of chaoticity is weakened with an increase of electric parameter Q and angular momentum L. The conclusion can also be supported by fast Lyapunov indicators.

The ability of bumblebee gravity models to explain dark energy, which is the phenomenon responsible for the universe’s observed accelerated expansion, is one of their most significant applications. An effect that causes faster expansion can be linked to how much the Lorentz symmetry of our universe is violated. Moreover, since we do not know what generates dark energy, the bumblebee gravity theory seems highly plausible. By utilizing the physical changes happening around a rotating bumblebee black hole (RBBH), we aim to obtain more specific details about the bumblebee black hole’s spacetime and our universe. However, as researched in the literature, slow-spinning RBBH (SRBBH) spacetime, which has a higher accuracy, will be considered instead of general RBBH. To this end, we first employ the Rindler–Ishak method (RIM), which enables us to study how light is bent in the vicinity of a gravitational lens. We evaluate the deflection angle of null geodesics in the equatorial plane of the SRBBH spacetime. Then, we use astrophysical data to see the effect of the Lorentz symmetry breaking (LSB) parameter on the bending angle of light for numerous astrophysical stars and black holes. We also acquire the analytical greybody factors (GFs) and quasinormal modes (QNMs) of the SRBBH. Finally, we visualize and discuss the results obtained in the conclusion section.

We investigate the dynamics of test particles endowed with both electric charge and a magnetic dipole moment around a Schwarzschild black hole (BH) immersed in an externally asymptotically uniform magnetic field. We further analyse the effective potential and specific angular momentum and energy of the particles. Furthermore, we show that the upper limit for magnetic interaction parameter β increases with increasing cyclotron frequency ωB, while the radius of the innermost stable circular orbit (ISCO) for charged test particles decreases for the upper value of β=βupper. Furthermore, we show that the energy efficiency released from the BH increases up to about 90% due to the presence of the magnetic dipole moment of the test particle. We explore a degeneracy between the spin parameter of rotating Kerr BH and the magnetic parameter for the values of the ISCO radius and energy efficiency. We study in detail the centre of mass energy for collisions of charged and magnetized particles in the environment surrounding the Schwarzchild BH. Finally, as an astrophysical application, we explore the magnetized parameter and cyclotron frequency numerically for a rotating magnetized neutron star. Interestingly, we show that the corresponding values of the above-mentioned parameters for the magnetar PSR J1745-2900 that orbits around the supermassive black hole (SMBH) that exists at the centre of the Milky Way galaxy are ωB≃5 and β≃0.67, respectively, for the magnetic field is about 10 G.

This investigation aims to explore certain variables which are considered responsible for generating pressure anisotropy in dynamical spherically symmetric stellar systems against the background of the stringy-inspired Gauss–Bonnet modification of general relativity. We explore the hydrostatic equilibrium of self-gravitating systems by taking into account the modified form of Tolman–Oppenheimer–Volkoff for the quadratic-f(G) gravitational model. In this respect, we formulate a differential equation in terms of the Weyl curvature scalar, also described as an evolution equation, which is essential for understanding the evolution of the stellar structure. Finally, we conclude that the existence of some fluid variables such as shear, heat flux and the irregular behavior of energy density in the presence of an extra degree f(G)-terms in the fluid flow that are the elements that cause anisotropy in the initially isotropic stellar structure. The comparison of the presented results with those of the classical model shows that they are physically relevant and compatible.

This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/., Analogue gravity systems offer many insights into gravitational phenomena, both at the classical and at the semiclassical level. The existence of an underlying Minkowskian structure (or Galilean in the non-relativistic limit) in the laboratory has been argued to directly forbid the simulation of geometries with Closed Timelike Curves (CTCs) within analogue systems. We will show that this is not strictly the case. In principle, it is possible to simulate spacetimes with CTCs whenever this does not entail the presence of a chronological horizon separating regions with CTCs from regions that do not have CTCs. We find an Analogue-gravity Chronology protection mechanism very similar in spirit to Hawking’s Chronology Protection hypothesis. We identify the universal behaviour of analogue systems near the formation of such horizons and discuss the further implications that this analysis has from an emergent gravity perspective. Furthermore, we build explicit geometries containing CTCs, for instance spacetimes constructed from two warp-drive configurations, that might be useful for future analysis, both from a theoretical and an experimental point of view. © The Author(s) 2022., Financial support was provided by the Spanish Government through the projects PID2020-118159GB-C43 and PID2020-118159GB-C44, and by the Junta de Andalucía through the project FQM219. C.B. and G.G.M. acknowledge financial support from the State Agency for Research of the Spanish MCIU through the “Center of Excellence Severo Ochoa” award to the Instituto de Astrofísica de Andalucía (SEV-2017-0709). GGM is funded by the Spanish Government fellowship FPU20/01684.

We study collisions of boosted rotating black holes in $D=6$ and 7 spacetime dimensions with a non-zero impact parameter. We find that there exists an open set of initial conditions such that the intermediate state of the collision is a black hole with a dumbbell-like horizon which is unstable to a local Gregory-Laflamme-type instability. We are able to provide convincing numerical evidence that the evolution of such an instability leads to a pinch off of the horizon in finite asymptotic time thus forming a naked singularity, as in similar unstable black holes. Since the black holes in the initial state are stable, this is the first genuinely generic evidence for the violation of the Weak Cosmic Censorship Conjecture in higher dimensional asymptotically flat spacetimes., 16 pages + appendices, 12 figures; v2: added computation of curvature scalar; text reformatting

A population of primordial black holes formed in the early Universe could contribute to at least a fraction of the black-hole merger events detectable by current and future gravitational-wave interferometers. With the ever-increasing number of detections, an important open problem is how to discriminate whether a given event is of primordial or astrophysical origin. We systematically present a comprehensive and interconnected list of discriminators that would allow us to rule out, or potentially claim, the primordial origin of a binary by measuring different parameters, including redshift, masses, spins, eccentricity, and tidal deformability. We estimate how accurately future detectors (such as the Einstein Telescope and LISA) could measure these quantities, and we quantify the constraining power of each discriminator for current interferometers. We apply this strategy to the GWTC-3 catalog of compact binary mergers. We show that current measurement uncertainties do not allow us to draw solid conclusions on the primordial origin of individual events, but this may become possible with next-generation ground-based detectors., Comment: 24 pages, 14 figures. v2: matching published version

NGC 253 is a nearby starburst galaxy in the Sculptor group located at a distance of ∼3.5 Mpc that has been suggested by some authors as a potential site for cosmic ray acceleration up to ultrahigh energies. Its nuclear region is heavily obscured by gas and dust, which prevents establishing whether or not the galaxy harbours a supermassive black hole coexisting with the starburst. Some sources have been proposed in the literature as candidates for an active nucleus. In this work, we aim at determining the implications that the presence of a supermassive black hole at the nucleus of NGC 253 might have on cosmic ray acceleration. With this aim, we model the accretion flow on to the putative active nucleus, and we evaluate the feasibility of particle acceleration by the black hole dynamo mechanism. As a by-product, we explore the potential contribution from non-thermal particles in the accretion flow to the high-energy emission of the galaxy. We found that in the three most plausible nucleus candidates, the emission of the accretion flow would inhibit the black hole dynamo mechanism. To rule out completely the influence that a putative nucleus in NGC 253 might have in cosmic ray acceleration, a better clarification concerning the true nature of the nucleus is needed., Instituto Argentino de Radioastronomía

The mass measurement of supermassive black holes (SMBHs) is a very complex task. Between several methods for SMBH mass measurements, some of them use the spectral lines, which indicate the motion of the emitting/absorbing material around an SMBH. Mostly, there is an assumption of virialization of line emitting gas in the region which is close to the central SMBH. In this paper we will give an overview of methods for the SMBH mass measurements using broad emission spectral lines observed in Type 1 AGNs. First we give the basic idea to use the parameters of broad lines to SMBH mass measurements. After that we give an overview of broad lines from X-ray (Fe kα) to the IR (Pashen and Brecket lines) which have been used for SMBH mass estimates. Additionally, we describe and discuss a new method for SMBH mass measurements using the polarization in the broad lines emitted from Type 1 AGNs.

LIGO Scientific Collaboration and Virgo Collaboration: et al., We report the observation of a compact binary coalescence involving a 22.2–24.3 M⊙ black hole and a compact object with a mass of 2.50–2.67 M⊙ (all measurements quoted at the 90% credible level). The gravitational-wave signal, GW190814, was observed during LIGO's and Virgo's third observing run on 2019 August 14 at 21:10:39 UTC and has a signal-to-noise ratio of 25 in the three-detector network. The source was localized to 18.5 deg2 at a distance of ${241}_{-45}^{+41}$ Mpc; no electromagnetic counterpart has been confirmed to date. The source has the most unequal mass ratio yet measured with gravitational waves, ${0.112}_{-0.009}^{+0.008}$, and its secondary component is either the lightest black hole or the heaviest neutron star ever discovered in a double compact-object system. The dimensionless spin of the primary black hole is tightly constrained to ≤0.07. Tests of general relativity reveal no measurable deviations from the theory, and its prediction of higher-multipole emission is confirmed at high confidence. We estimate a merger rate density of 1–23 Gpc−3 yr−1 for the new class of binary coalescence sources that GW190814 represents. Astrophysical models predict that binaries with mass ratios similar to this event can form through several channels, but are unlikely to have formed in globular clusters. However, the combination of mass ratio, component masses, and the inferred merger rate for this event challenges all current models of the formation and mass distribution of compact-object binaries., The authors gratefully acknowledge the support of the United States National Science Foundation (NSF) for the construction and operation of the LIGO Laboratory and Advanced LIGO as well as the Science and Technology Facilities Council (STFC) of the United Kingdom, the Max-Planck-Society (MPS), and the State of Niedersachsen/Germany for support of the construction of Advanced LIGO and construction and operation of the GEO600 detector. Additional support for Advanced LIGO was provided by the Australian Research Council. The authors gratefully acknowledge the Italian Istituto Nazionale di Fisica Nucleare (INFN), the French Centre National de la Recherche Scientifique (CNRS) and the Netherlands Organization for Scientific Research, for the construction and operation of the Virgo detector and the creation and support of the EGO consortium. The authors also gratefully acknowledge research support from these agencies as well as by the Council of Scientific and Industrial Research of India, the Department of Science and Technology, India, the Science & Engineering Research Board (SERB), India, the Ministry of Human Resource Development, India, the Spanish Agencia Estatal de Investigación, the Vicepresidencia i Conselleria d’Innovació, Recerca i Turisme and the Conselleria d’Educació i Universitat del Govern de les Illes Balears, the Conselleria d’Innovació, Universitats, Ciencia i Societat Digital de la Generalitat Valenciana and the CERCA Programme Generalitat de Catalunya, Spain, the National Science Centre of Poland, the Swiss National Science Foundation (SNSF), the Russian Foundation for Basic Research, the Russian Science Foundation, the European Commission, the European Regional Development Funds (ERDF), the Royal Society, the Scottish Funding Council, the Scottish Universities Physics Alliance, the Hungarian Scientific Research Fund (OTKA), the French Lyon Institute of Origins (LIO), the Belgian Fonds de la Recherche Scientifique (FRS-FNRS), Actions de Recherche Concertees (ARC) and Fonds Wetenschappelijk Onderzoek–Vlaanderen (FWO), Belgium, the Paris Île-de-France Region, the National Research, Development and Innovation Office Hungary (NKFIH), the National Research Foundation of Korea, Industry Canada and the Province of Ontario through the Ministry of Economic Development and Innovation, the Natural Science and Engineering Research Council Canada, the Canadian Institute for Advanced Research, the Brazilian Ministry of Science, Technology, Innovations, and Communications, the International Center for Theoretical Physics South American Institute for Fundamental Research (ICTPSAIFR), the Research Grants Council of Hong Kong, the National Natural Science Foundation of China (NSFC), the Leverhulme Trust, the Research Corporation, the Ministry of Science and Technology (MOST), Taiwan and the Kavli Foundation. The authorsgratefully acknowledge the support of the NSF, STFC, INFN and CNRS for provision of computational resources.

A characteristic value formulation of the Weyl double copy leads to an asymptotic formulation. We find that the Weyl double copy holds asymptotically in cases where the full solution is algebraically general, using rotating STU supergravity black holes as an example. The asymptotic formulation provides clues regarding the relation between asymptotic symmetries that follows from the double copy. Using the C-metric as an example, we show that a previous interpretation of this gravity solution as a superrotation has a single copy analogue relating the appropriate Li\'enard-Wiechert potential to a large gauge transformation., Comment: 52 pages (27 for main body), one figure. v2 updated references

We introduce an ensemble of artificial intelligence models for gravitational wave detection that we trained in the Summit supercomputer using 32 nodes, equivalent to 192 NVIDIA V100 GPUs, within 2 hours. Once fully trained, we optimized these models for accelerated inference using NVIDIA TensorRT. We deployed our inference-optimized AI ensemble in the ThetaGPU supercomputer at Argonne Leadership Computer Facility to conduct distributed inference. Using the entire ThetaGPU supercomputer, consisting of 20 nodes each of which has 8 NVIDIA A100 Tensor Core GPUs and 2 AMD Rome CPUs, our NVIDIA TensorRT-optimized AI ensemble processed an entire month of advanced LIGO data (including Hanford and Livingston data streams) within 50 seconds. Our inference-optimized AI ensemble retains the same sensitivity of traditional AI models, namely, it identifies all known binary black hole mergers previously identified in this advanced LIGO dataset and reports no misclassifications, while also providing a 3X inference speedup compared to traditional artificial intelligence models. We used time slides to quantify the performance of our AI ensemble to process up to 5 years worth of advanced LIGO data. In this synthetically enhanced dataset, our AI ensemble reports an average of one misclassification for every month of searched advanced LIGO data. We also present the receiver operating characteristic curve of our AI ensemble using this 5 year long advanced LIGO dataset. This approach provides the required tools to conduct accelerated, AI-driven gravitational wave detection at scale., 19 pages, 8 figures; v2. Accepted to Frontiers in Artificial Intelligence, Special Issue: Efficient AI in Particle Physics and Astrophysics

We study the evolution of the Gregory-Laflamme instability for black strings in global AdS spacetime, and investigate the CFT dual of the formation of a bulk naked singularity. Using an effective theory in the large D limit, we uncover a rich variety of dynamical behaviour, depending on the thickness of the string and on initial perturbations. These include: large inflows of horizon generators from the asymptotic boundary (a `black tsunami'); a pinch-off of the horizon that likely reveals a naked singularity; and competition between these two behaviours, such as a nakedly singular pinch-off that subsequently gets covered by a black tsunami. The holographic dual describes different patterns of heat flow due to the Hawking radiation of two black holes placed at the antipodes of a spherical universe. We also present a model that describes, in any D, the burst in the holographic stress-energy tensor when the signal from a bulk self-similar naked singularity reaches the boundary. The model shows that the shear components of the boundary stress diverge in finite time, while the energy density and pressures from the burst vanish., 30 pages, 7 figures. v2: minor typos fixed. Matches published version

Recently, the reflected entropy is proposed in holographic approach to describe the entanglement of a bipartite quantum system in a mixed state, which is identified as the area of the reflected minimal surface inside the entanglement wedge. In this paper, we study the reflected entropy in the doubly holographic setup, which contains the degrees of freedom of quantum matter in the bulk. In this context, we propose a notion of quantum entanglement wedge cross-section, which may describe the reflected entropy with higher-order quantum corrections. We numerically compute the reflected entropy in pure AdS background and black hole background in four dimensions, respectively. In general, the reflected entropy contains the contribution from the geometry on the brane and the contribution from the CFT. We compute their proportion for different Newton constants and find that their behaviors are in agreement with the results based on the semi-classical gravity and the correlation of CFT coupled to the bath CFT., Comment: 25 pages, 9 figures, minor correction, published version

We present a construction of the most general BPS black holes of STU supergravity (${\cal N}=2$ supersymmetric $D=4$ supergravity coupled to three vector super-multiplets) with arbitrary asymptotic values of the scalar fields. These solutions are obtained by acting with a subset of of the global symmetry generators on STU BPS black holes with zero values of the asymptotic scalars, both in the U-duality and the heterotic frame. The solutions are parameterized by fourteen parameters: four electric and four magnetic charges, and the asymptotic values of the six scalar fields. We also present BPS black hole solutions of a consistently truncated STU supergravity, which are parameterized by two electric and two magnetic charges and two scalar fields. These latter solutions are significantly simplified, and are very suitable for further explicit studies. We also explore a conformal inversion symmetry of the Couch-Torrence type, which maps any member of the fourteen-parameter family of BPS black holes to another member of the family. Furthermore, these solutions are expected to be valuable in the studies of various swampland conjectures in the moduli space of string compactifications., V2. Updated reference. Minor changes to the concluding remarks and outlook section

We investigate the second law of black hole mechanics in gravitational theories with higher derivative terms in the action. Wall has described a method for defining an entropy that satisfies the second law to linear order in perturbations around a stationary black hole. We show that this can be extended to define an entropy that satisfies the second law to quadratic order in perturbations, provided that one treats the higher derivative terms in the sense of effective field theory. We also address some outstanding issues with Wall's method, in particular, its gauge invariance and its relation to the Iyer-Wald entropy., Comment: 57 pages + Appendix; v2: typos corrected, references added; v3: argument of section 4 simplified, typos corrected