On the charge of the Galactic centre black hole

@article{30302,
   author = {Zajaček, Michal and Tursunov, Arman and Eckart, Andreas and Britzen, Silke},
   article_number = {4},
   doi = {http://dx.doi.org/10.1093/mnras/sty2182},
   keywords = {Galaxy: centre; black hole physics; radiation mechanisms: general},
   language = {eng},
   issn = {0035-8711},
   journal = {Monthly Notices of the Royal Astronomical Society},
   title = {On the charge of the Galactic centre black hole},
   url = {https://academic.oup.com/mnras/article-abstract/480/4/4408/5069413?redirectedFrom=fulltext},
   volume = {480},
   year = {2018}
}

TY  - JOUR
ID  - 30302
AU  - Zajaček, Michal - Tursunov, Arman - Eckart, Andreas - Britzen, Silke
PY  - 2018
TI  - On the charge of the Galactic centre black hole
JF  - Monthly Notices of the Royal Astronomical Society
VL  - 480
IS  - 4
SP  - 4408-4423
EP  - 4408-4423
SN  - 00358711
KW  - Galaxy: centre
KW  - black hole physics
KW  - radiation mechanisms: general
UR  - https://academic.oup.com/mnras/article-abstract/480/4/4408/5069413?redirectedFrom=fulltext
L2  - https://academic.oup.com/mnras/article-abstract/480/4/4408/5069413?redirectedFrom=fulltext
N2  - The Galactic centre supermassive black hole (SMBH), in sharp contrast with its complex environment, is characterized by only three classical parameters - mass, spin, and electric charge. Its charge is poorly constrained. It is, however, usually assumed to be zero because of neutralization due to the presence of plasma. We revisit the question of the SMBII charge and put realistic limits on its value, time-scales of charging and discharging, and observable consequences of the potential, small charge associated with the Galactic centre black hole. The electric charge due to classical arguments based on the mass difference between protons and electrons is less than or similar to 10^9 C and is of a transient nature on the viscous time-scale. However, the rotation of a black hole in magnetic field generates electric field due to the twisting of magnetic field lines. This electric field can be associated with induced charge, for which we estimate an upper limit of less than or similar to 10^{15} C. Moreover, this charge is most likely positive due to an expected alignment between the magnetic field and the black hole spin. Even a small charge of this order significantly shifts the position of the innermost stable circular orbit (ISCO) of charged particles. In addition, we propose a novel observational test based on the presence of the bremsstrahlung surface brightness decrease, which is more sensitive for smaller unshielded electric charges than the black hole shadow size. Based on this test, the current upper observational limit on the charge of Sgr A* is less than or similar to 3 x 10^8 C.
ER  - 

ZAJAČEK, Michal, Arman TURSUNOV, Andreas ECKART a Silke BRITZEN. On the charge of the Galactic centre black hole. \textit{Monthly Notices of the Royal Astronomical Society}. 2018, roč.~480, č.~4, s.~4408-4423. ISSN~0035-8711. Dostupné z: https://dx.doi.org/10.1093/mnras/sty2182.