Constraining the charge of the Galactic centre black hole

authored by: Michal Zajaček, Arman Tursunov, Andreas Eckart, Silke Britzen, Eva Hackmann, Vladimír Karas, Zdeněk Stuchlík, Bozena Czerny, J. Anton Zensus
Abstract: In this contribution, we summarize our results concerning the observational constraints on the electric charge associated with the Galactic centre black hole - Sgr A∗. According to the no-hair theorem, every astrophysical black hole, including supermassive black holes, is characterized by at most three classical, externally observable parameters - mass, spin, and the electric charge. While the mass and the spin have routinely been measured by several methods, the electric charge has usually been neglected, based on the arguments of efficient discharge in astrophysical plasmas. From a theoretical point of view, the black hole can attain charge due to the mass imbalance between protons and electrons in fully ionized plasmas, which yields about ∼ 10⁸ C for Sgr A∗. The second, induction mechanism concerns rotating Kerr black holes embedded in an external magnetic field, which leads to electric field generation due to the twisting of magnetic field lines. This electric field can be associated with the induced Wald charge, for which we calculate the upper limit of ∼ 10¹⁵ C for Sgr A∗. Although the maximum theoretical limit of ∼ 10¹⁵ C is still 12 orders of magnitude smaller than the extremal charge of Sgr A∗, we analyse a few astrophysical consequences of having a black hole with a small charge in the Galactic centre. Two most prominent ones are the effect on the X-ray bremsstrahlung profile and the effect on the position of the innermost stable circular orbit.
External Organisation(s): Max Planck Institute for Radio Astronomy (MPIfR)
University of Cologne
Silesian University in Opava
Czech Academy of Sciences (CAS)
Center of Applied Space Technology and Microgravity (ZARM)
Polish Academy of Sciences (PASIFIC)
Type: Conference article
Journal: Journal of Physics: Conference Series
Volume: 1258
No. of pages: 17
ISSN: 1742-6588
Publication date: 21.10.2019
Publication status: Published
Peer reviewed: Yes
ASJC Scopus subject areas: Physics and Astronomy(all)
Electronic version(s): https://doi.org/10.48550/arXiv.1812.03574 (Access: Open)
https://doi.org/10.1088/1742-6596/1258/1/012031 (Access: Open)

BibTeX

@article{1733e61661944de7a22888d64a3ee89e,
title = "Constraining the charge of the Galactic centre black hole",
abstract = "In this contribution, we summarize our results concerning the observational constraints on the electric charge associated with the Galactic centre black hole - Sgr A∗. According to the no-hair theorem, every astrophysical black hole, including supermassive black holes, is characterized by at most three classical, externally observable parameters - mass, spin, and the electric charge. While the mass and the spin have routinely been measured by several methods, the electric charge has usually been neglected, based on the arguments of efficient discharge in astrophysical plasmas. From a theoretical point of view, the black hole can attain charge due to the mass imbalance between protons and electrons in fully ionized plasmas, which yields about ∼ 108 C for Sgr A∗. The second, induction mechanism concerns rotating Kerr black holes embedded in an external magnetic field, which leads to electric field generation due to the twisting of magnetic field lines. This electric field can be associated with the induced Wald charge, for which we calculate the upper limit of ∼ 1015 C for Sgr A∗. Although the maximum theoretical limit of ∼ 1015 C is still 12 orders of magnitude smaller than the extremal charge of Sgr A∗, we analyse a few astrophysical consequences of having a black hole with a small charge in the Galactic centre. Two most prominent ones are the effect on the X-ray bremsstrahlung profile and the effect on the position of the innermost stable circular orbit.",
author = "Michal Zaja{\v c}ek and Arman Tursunov and Andreas Eckart and Silke Britzen and Eva Hackmann and Vladim{\'i}r Karas and Zden{\v e}k Stuchl{\'i}k and Bozena Czerny and Zensus, {J. Anton}",
note = "Publisher Copyright: {\textcopyright} 2019 IOP Publishing Ltd. All rights reserved.; 1st Sharjah International Conference on Particle Physics, Astrophysics and Cosmology, FISICPAC 2018 ; Conference date: 11-11-2018 Through 13-11-2018",
year = "2019",
month = oct,
day = "21",
doi = "10.48550/arXiv.1812.03574",
language = "English",
volume = "1258",
journal = "Journal of Physics: Conference Series",
issn = "1742-6588",
publisher = "IOP Publishing Ltd.",
number = "1",
}