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Zhiren Wang (Perimeter Institute & University of Waterloo)24/08/2026, 14:00
Scalar ultralight boson clouds around rotating black holes can generate long-lived, non-axisymmetric gravitational perturbations capable of exciting coherent dynamical responses in nearby accretion flows. Focusing on black hole X-ray binaries, we investigate whether this forcing can excite global oscillations of a thin accretion disk and produce observable quasi-periodic variability. Using a...
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Yu-Ming Yang (IHEP)24/08/2026, 14:15
As an alternative theory to cold dark matter (CDM), fuzzy dark matter (FDM) has recently attracted widespread attention. FDM consists of ultra-light bosons with masses around 10^{-22} eV. At typical galactic velocities, their de Broglie wavelength can reach kiloparsec (kpc) scales, thereby exhibiting unique wave-like behavior on galactic scales. This leads to complex evolutionary dynamics and...
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Chen Sun (HIAS-UCAS)24/08/2026, 14:30
Many well-motivated UV theories contain bonsonic light degrees of freedom, which can exhibit various wave-like behaviors at low energy. This leads to many new ideas and novel observables in recent years to probe new physics in astrophysical and laboratory setups alike. In this talk, I will briefly review a few examples in leveraging the wave-like features to test axions and ultralight dark...
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Fengwei Yang (University of Notre Dame)24/08/2026, 14:45
The existence of a superradiant axion cloud around a black hole X-ray binary can heat its accretion disk and be detected in a thermal X-ray spectrum. We consider a derivative coupling between axions and fermions and calculate the emissivity of the inverse bremsstrahlung process, which results in a temperature fluctuation of the disk. The energy injection rate per baryon by axion heating is...
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Chen Yuan (Shanghai University)24/08/2026, 15:00
Gravitational waves open a new window onto black holes and their surrounding environments. Realistic environments such as ultralight bosonic fields and accretion environments can leave observable signatures in gravitational wave signals. This talk explores how such environmental effects can be used to probe fundamental physics and astrophysics. Topics include gravitational waves from...
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Zhi-Qing Zhu (ICTP-AP)24/08/2026, 15:15
We investigate black hole superradiance evolution of the interacting multiple fields. We consider a model of two scalar fields interacting with a cubic coupling, and study the superradiant evolution of the cloud. We demonstrate that superradiance is typically suppressed when the superradiant field couples to another field, even with a very weak coupling strength. This implies that the...
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Ximeng Li (TDLI)24/08/2026, 16:00
Axion fields can form exponentially growing gravitational clouds around compact objects through self-interaction–driven relaxation of ambient axion waves. As the field amplitude approaches the axion decay constant, nonlinear effects become important. We identify two distinct regimes of late-time evolution, determined by the gravitational fine-structure constant and the cloud growth rate: a...
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Dr Hailin Xu (Tsung-Dao Lee Institute)24/08/2026, 16:15
Quadratically coupled ultralight scalar dark matter behaves as a coherent classical field whose interactions with matter can induce a composition-dependent force through the dark matter background. We present a complete calculation of this background-induced force beyond the spherically symmetric approximation. Using a partial-wave treatment of dark-matter scattering, we determine its angular...
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Ziwen Yin (Tsung-Dao Lee Institute & SJTU)24/08/2026, 16:30
The orbital evolution of the Hulse-Taylor binary neutron star system is described with high precision by General Relativity, in which gravity is the only long-range force and gravitational waves provide the dominant energy-loss channel. We use this precision test of relativistic binary dynamics to derive new constraints on axion couplings to stable neutron-star constituents: neutrons,...
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Zhen-Hong Lyu (Institute of Theoretical Physics, Chinese Academy of Sciences)24/08/2026, 16:45
Ultralight bosons around spinning black holes can form macroscopic gravitational atoms through superradiance. We show that attractive self-interactions can turn such systems into periodically varying lenses for gravitational waves. During the long-lived 211–322 quasi-equilibrium, coherent interference between the dominant 211 cloud and the self-interaction-populated 322 level produces an...
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Yanjie Zeng (Peking University)24/08/2026, 17:00
The Event Horizon Telescope (EHT) has significantly advanced our ability to study black holes, achieving unprecedented spatial resolution and revealing horizon-scale structures. Notably, these observations feature a distinctive dark shadow—primarily arising from faint jet emissions—surrounded by a bright photon ring. Anticipated upgrades of the EHT promise substantial improvements in dynamic...
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Yuxin Liu24/08/2026, 17:15
Neutron stars are known to constrain asymmetric dark matter because accumulated particles can trigger collapse. I will show that these constraints extend much further: even when dark matter is produced with equal particle and antiparticle abundances, the capture process inside a neutron star can become intrinsically asymmetric if the two species scatter off nucleons with slightly different...
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Bo-Xuan Ge25/08/2026, 14:00
Numerical-relativity data are not generic arrays to be enhanced, but
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discretized geometric fields constrained by the Einstein equations. We
introduce AI(\times)NR-Pathfinder, a constraint-aware learning framework
that applies small, stencil-consistent correction operators to
(3+1) numerical-relativity slices while preserving the algebraic
structure of the conformal variables. The... -
Alejandra Gonzalez (University of the Balearic Islands)25/08/2026, 14:15
We present 52 new numerical-relativity (NR) simulations of black-hole-neutron-star merger (BHNS) mergers and employ the data to inform a multipolar effective-one-body model for complete waveforms from arbitrary mergers. Our simulations target quasicircular mergers and the parameter space region characterized by significant tidal disruption of the star. Convergent gravitational waveforms are...
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Kunyang Li (Center for Computational Astrophysics, Flatiron Institute)25/08/2026, 14:30
Low-frequency gravitational-wave surveys need not just how often massive black holes (MBHs) merge, but the parameters carried to coalescence: masses, mass ratio, spins, eccentricity, and the delay since galaxy assembly. These depend on dynamical regimes that cosmological galaxy simulations cannot resolve. We extend RAMCOAL, a subgrid model in the RAMSES hydrodynamical code, to follow MBH...
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专 宁25/08/2026, 14:45
We present a numerical-relativity study of comparable-mass boson star-black hole (BS-BH) head-on collisions, focusing on both initial-data construction and gravitational-wave (GW) phenomenology. We show that plain superposition can strongly perturb the BS core, leading to large constraint violations and unphysical radial oscillations. To remedy this problem, we introduce a one-body...
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Jian-dong Zhang (Sun Yat-sen Univeristy)25/08/2026, 15:00
The major challenge for the fast generation of such waveforms is the generation of the Teukolsky amplitudes for generic (eccentric and inclined) Kerr orbits. The requirement forthe modeling of ∼ 10^5 harmonic modes across a four-dimensional parameter space makes traditional approaches, including direct computation or dense interpolation, computationally prohibitive. To overcome this issue, we...
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Yuhe Zeng (Tsung-Dao Lee Institute, Shanghai Jiao Tong University)25/08/2026, 15:15
A small body orbiting around an accreting massive object and periodically crossing its accretion disk is a
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common configuration in astrophysics. In this work, we study the secular evolution of extreme mass-ratio
inspirals (EMRIs), where a stellar-mass object (SMO)—such as a star or a stellar-mass black hole (sBH)—
collides with the accretion disk surrounding a central supermassive black... -
Haitian Wang (Dalian University of Technology)25/08/2026, 16:00
Gravitational-wave observations offer a powerful way to probe compact binary coalescences and test strong-field gravity. In this talk, I will present a preliminary study on gravitational-wave data analysis using the F-statistic, focusing on its applications to black-hole ringdown and full inspiral–merger–ringdown analyses. By analytically maximizing over amplitude-related parameters, the...
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Uddeepta Deka (Shanghai Astronomical Observatory - Chinese Academy of Sciences)25/08/2026, 16:15
Gravitational-wave (GW) microlensing occurs when an intervening compact object diffracts the GW in the wave-optics regime, imprinting characteristic frequency-dependent modulations on the observed signal. Current searches for microlensing signatures in the detected GW events assume an isolated point mass lens (PML) model. However, this assumption is overly simplistic. Astrophysical microlenses...
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Hanyu Cheng25/08/2026, 16:30
Pulsar timing arrays are becoming sensitive to individual supermassive black hole binaries above the nanohertz gravitational-wave background. I will present a harmonic-space framework that consistently incorporates irregular pulsar sampling, non-uniform noise, source confusion, and pulsar terms. By marginalizing over unknown pulsar phases, we obtain a parameter-dependent covariance and derive...
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迈 乔 (International Centre for Theoretical Physics Asia-Pacific, University of Chinese Academy of Sciences)25/08/2026, 16:45
The stochastic gravitational-wave backgrounds are expected to arise from the superposition of many individually unresolved sources throughout cosmic history, carrying information about compact-binary populations, gravity beyond general relativity, and possible processes in the early Universe. In this talk, I will present recent progress in the LIGO-Virgo-KAGRA search for an isotropic...
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Mr Shitong Guo (Nankai University)25/08/2026, 17:00
Gravitational-wave ringdowns encode the characteristic oscillation spectrum of the compact remnant and provide a direct probe of strong-field gravity. Yet conventional analyses usually infer remnant properties with theory-specific waveform templates, entangling the information extracted from the data with the assumed model. Ringdown inference is also often treated in isolation, leaving aside...
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Charchit Kumar Sethi (International Center for Theoretical Physics, Asia Pacific (ICTP-AP)/ University Chinese Academy of Sciences (UCAS,中国科学院大学))25/08/2026, 17:15
Primordial black holes (PBHs) are compelling dark matter (DM) candidates; however, current observational constraints indicate that they can not account for the entirety of the DM abundance. This motivates scenarios in which additional DM components coexist with PBHs and form dense structures, often referred to as ``dark dresses,'' around them. Such environments induce dynamical friction,...
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Avi Vajpeyi (University of Auckland)25/08/2026, 17:30
Accurate and scalable noise modelling will be essential for extracting weak gravitational-wave signals and signatures of new physics from LISA data. Realistic time-delay interferometry channels may contain frequency-dependent correlations, while the detector noise may also evolve over the mission.
I will present a Bayesian framework for estimating the full spectral density matrix of...
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Takuya Takahashi (The University of Tokyo)27/08/2026, 14:00
Extreme mass ratio inspirals (EMRIs) are among the key targets for future gravitational wave observations. While the study of EMRIs in vacuum has been extensively developed over the past decades, environmental effects arising from matter surrounding black holes have also attracted significant attention in recent years. A proper understanding of such effects may open up the possibility of...
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Qi-Xuan Xu (Instituto Superior Técnico)27/08/2026, 14:15
Through black hole superradiance, ultralight bosonic fields may form macroscopic clouds around rotating black holes. Extreme-mass-ratio inspirals (EMRIs), among the primary targets of future space-based gravitational-wave detectors, provide a unique opportunity to probe such environments. We extend the relativistic perturbative framework for EMRIs within scalar clouds from circular, equatorial...
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江川 于 (北京大学)27/08/2026, 14:30
The dense environment of our Galactic Center (GC) offers a unique laboratory for probing ultralight dark matter (ULDM). We explore the prospect of detecting a scalar ULDM field through its effects on the orbital dynamics of S-stars around the supermassive black hole in the GC, Sgr A$^*$. We consider both linear and quadratic couplings between the real scalar field $\phi$ and Standard Model...
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Ao Guo (International Centre for Theoretical Physics Asia-Pacific, University of Chinese Academy of Sciences, 100190 Beijing, China)27/08/2026, 14:45
Ultralight bosons, such as axion-like particles, are promising candidates for physics beyond the Standard Model. Rotating black holes can amplify these fields through superradiance, forming macroscopic bosonic clouds known as gravitational atoms. In this work, we investigate the evolution of ultralight boson clouds in binary black hole systems, considering their full evolutionary history from...
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Yuhao Guo27/08/2026, 15:00
Detection of gravitational waves enables probes of environmental effects around compact binaries. Ultralight bosons, well motivated in particle physics and capable of forming core-like dark matter structures, induce environmental dynamics that differ qualitatively from
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those produced by stars or particle dark matter. For comparable-mass binaries, such bosons can form gravitationally bound...
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