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GR: Fachverband Gravitation und Relativitätstheorie

GR 18: Poster

GR 18.1: Poster

Thursday, March 14, 2024, 17:15–18:45, HBR 14: Foyer

Questionable predictions by EHT image of Sgr A*; observational evidence for Sgr A* being no BH; de Laval nozzle and its application to astrophysical jets. — •Jürgen Brandes — Karlsbad, Germany

I. The famous EHT image of Sgr A* predicts BH features in contradiction with observation: a* = 0.9375 against a* ≤ 0.15; spin direction face-on against edge-on; accretion light variability arising with accretion disks against variability of accretion wind. And there is a theoretical shortcut by Broderick et al.: The missing UV bump agrees with degenerate supermassive objects being no BH [1], [2].
II. Furthermore, [3] proves: If Sgr A* is a BH then its spin must be a* = 0.90. But [1] proves that the spin of Sgr A* ≤ 0.15. The purely logical conclusion: Sgr A* cannot be a BH (contrary to [3], its spin would be too low). These observations of Fragione, Loeb, Daly et al. together are an obvious experimental confirmation for Sgr A* not being a BH [1], [3].
III. Jets of supermassive objects being no BH are quite natural explained by astronomical application of a de Laval nozzle [4]. Since this does not work for BHs it should lead to observable differences between BHs and no BH stellar objects.

[1] Talk-DPG-2023 www.grt-li.de.

[2] J. Brandes, J. Czerniawski, L. Neidhart: Special and general relativity... VRI: 2023

[3] R. A. Daly et al., MNRAS 2024, 428 - 436

[4] P. Subramanian, Fluid Dynamics for Astrophysics, 2021, lec. 31