Conveners
Parallel sessions: Late universe cosmology
- Arman Shafieloo (Korea Astronomy and Space Science Institute)
Parallel sessions: Mathematical Relativity (including ACGRG/NZ Gravity Student Talks)
- Volker Schlue (University of Melbourne)
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Ming Chung Chu (The Chinese University of Hong Kong (HK))06/07/2026, 15:40Parallel Session Talk
In an earlier work, we performed a statistical analysis of the angular distribution of the cosmological parameters by adding hemispherical masks in different directions to the Planck 2018 CMB temperature and polarization data. We found that the standard ÅCDM parameters Ωbh2, Ωch2, ns, 100θMC, and H0 closely follow a dipole form, with 2-3 σ-level directional variations. The dipole axes all...
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Malcolm Anderson (Universiti Brunei Darussalam)06/07/2026, 16:00Parallel Session Talk
Many of the predictions of theoretical cosmology are generated by perturbing around a background FLRW space-time. This procedure is problematic, because the dependence of observables on the perturbations of the metric tensor varies with the choice of coordinates (or gauge) in the perturbed space-time. Moreover, the gauge choice is rarely uniform, as for example luminosity distances and...
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Dr Pierre Mourier (University of Canterbury)06/07/2026, 16:20Parallel Session Talk
The late-time Universe features nonlinear local deviations from strict homogeneity and isotropy as matter structures develop. These inhomogeneities may have a non-negligible impact on the cosmological expansion at the largest scales. Such "backreaction" effects from the presence of structures, including the growth of spatial curvature over large regions, can partially mimic the dynamical...
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Nitesh Dubey (Indian Institute of Astrophysics, Bengaluru)08/07/2026, 15:40Parallel Session Talk
The final equilibrium stage of stellar evolution may result in either a black hole or a compact object such as a white/black dwarf or neutron star. In general relativity, both stationary black holes and stationary stellar configurations are known to be axisymmetric, and black hole rigidity has been extended to several higher curvature modifications of gravity. In contrast, no comparable result...
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Mr Nihar Ranjan Ghosh08/07/2026, 16:00Parallel Session Talk
The Bondi-van der Burg-Metzner-Sachs (BMS) group, as the asymptotic symmetry group of asymptotically flat spacetimes, plays a central role in connecting infrared structures of gravity with soft theorems and gravitational memory. In this work, we investigate the extent to which BMS supertranslations can relate physically distinct black hole geometries. Focusing on the Schwarzschild and Kerr...
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Travers Bloemsaat08/07/2026, 16:20Parallel Session Talk
The stability of the inner structure of an irrotational charged black hole is a significant issue in relativity, serving as a prototype for the much more complicated problem of internal stability of a rotating charged black hole. Linear results suggest that the inner structure of a charged black hole is unstable under gravitational and electromagnetic perturbations. However, non-linear work on...
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Areeba Merriam (University of Canterbury)08/07/2026, 16:40Parallel Session Talk
Gravitational waves, first predicted by Albert Einstein in 1916, are ripples in spacetime that travel at the speed of light. They were only recently detected directly by observatories like LIGO and are generated when massive objects, such as black holes or neutron stars, collide. They are important because they can provide information that electromagnetic radiation from surrounding matter...
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Chris Stevens (University of Canterbury)08/07/2026, 17:00Parallel Session Talk
We present fully nonlinear numerical simulations of asymptotically flat spacetimes whose computational domain includes both past and future null infinity. Using Friedrich's generalised conformal field equations, we study the scattering of gravitational waves by a Schwarzschild black hole and compute asymptotic quantities, including the Bondi energy and Bondi news, on both null infinities. This...
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