Speaker
Description
In 2005 we predicted that based on VLBI observations it would be possible reconstruct a small dark spot (shadow) at the Galactic Center. Using current available estimates for distance and mass of the black hole we evaluated the shadow diameter as 50 μas.
Later, the Event Horizon Telescope Collaboration observations and its data analysis have confirmed our predictions. Really, in 2019 the Event Horizon Telescope (EHT) team presented the first image reconstruction around the shadow for the supermassive black hole in M87. In 2021 the EHT Collaboration constrained parameters (“charges”) of spherical symmetrical metrics of black holes from an allowed interval for shadow radius. Earlier, we obtained analytical expressions for the shadow radius as a function of charge (including a tidal one) in the case of Reissner–Nordström metric. Based on results of the shadow size evaluation for M87 done by the EHT collaboration we constrained a tidal charge. Similarly we constrained a tidal charge for the black hole at the Galactic Center based on shadow reconstruction done by EHT in 2022. We discuss opportunities to use shadows to test alternative theories of gravity and alternative models for galactic centers. We use also observational data for trajectories of bright stars near the Galactic Center to test gravity theories and theoretical models for the Galactic Center. In particular we found graviton mass bounds.
Details
Dr. Alexander F. Zakharov (Joint Institute for Nuclear Research, Dubna, Russia)
https://www.jinr.ru/main-en/
| Internet talk | Yes |
|---|---|
| Is this an abstract from experimental collaboration? | No |
| Name of experiment and experimental site | N/A |
| Is the speaker for that presentation defined? | Yes |
