THE ELECTRIC CHARGE OF BLACK HOLES: IS IT REALLY ALWAYS NEGLIGIBLE?

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F47813059%3A19240%2F19%3AA0000567" target="_blank" >RIV/47813059:19240/19:A0000567 - isvavai.cz</a>

Výsledek na webu

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DOI - Digital Object Identifier

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Jazyk výsledku

angličtina

Název v původním jazyce

THE ELECTRIC CHARGE OF BLACK HOLES: IS IT REALLY ALWAYS NEGLIGIBLE?

Popis výsledku v původním jazyce

We discuss the problem of the third black-hole parameter- an electric charge. While the mass and the spin of black holes are frequently considered in the majority of publications, the charge is often neglected and implicitly set identically to zero. However, both classical and relativistic processes can lead to a small nonzero charge of black holes. When dealing with neutral particles and photons, zero charge is a good approximation. On the other hand, even a small charge can significantly influence the motion of charged particles, in particular cosmic rays, in the vicinity of black holes. Therefore, we stress that more attention should be paid to the problem of a black-hole charge; and hence it should not be neglected a priori, as is done in most astrophysical studies nowadays. We look at the problem of the black-hole charge mainly from the astrophysical point of view, which is complemented by a few historical as well as philosophical notes when relevant. In particular, we show that a cosmic ray or, more generally, elementary charged particles, passing a non-neutral black hole can experience an electromagnetic force at least sixteen times the gravitational force (calculated for a proton) for the mass of the Galactic Centre black hole and its charge being seventeen orders of magnitude less than the extremal value. Furthermore, a Kerr-Newman rotating black hole with the maximum likely charge of one Coulomb per solar mass can have the position of its innermost stable circular orbit (ISCO) moved by both rotation and charge in ways that can enhance or partly cancel each other, putting the ISCO not far from the gravitational radius or out at more than six gravitational radii. An interpretation of X-ray radiation from near the ISCO of a black hole in X-ray binaries is then no longer unique.

Název v anglickém jazyce

THE ELECTRIC CHARGE OF BLACK HOLES: IS IT REALLY ALWAYS NEGLIGIBLE?

Popis výsledku anglicky

We discuss the problem of the third black-hole parameter- an electric charge. While the mass and the spin of black holes are frequently considered in the majority of publications, the charge is often neglected and implicitly set identically to zero. However, both classical and relativistic processes can lead to a small nonzero charge of black holes. When dealing with neutral particles and photons, zero charge is a good approximation. On the other hand, even a small charge can significantly influence the motion of charged particles, in particular cosmic rays, in the vicinity of black holes. Therefore, we stress that more attention should be paid to the problem of a black-hole charge; and hence it should not be neglected a priori, as is done in most astrophysical studies nowadays. We look at the problem of the black-hole charge mainly from the astrophysical point of view, which is complemented by a few historical as well as philosophical notes when relevant. In particular, we show that a cosmic ray or, more generally, elementary charged particles, passing a non-neutral black hole can experience an electromagnetic force at least sixteen times the gravitational force (calculated for a proton) for the mass of the Galactic Centre black hole and its charge being seventeen orders of magnitude less than the extremal value. Furthermore, a Kerr-Newman rotating black hole with the maximum likely charge of one Coulomb per solar mass can have the position of its innermost stable circular orbit (ISCO) moved by both rotation and charge in ways that can enhance or partly cancel each other, putting the ISCO not far from the gravitational radius or out at more than six gravitational radii. An interpretation of X-ray radiation from near the ISCO of a black hole in X-ray binaries is then no longer unique.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

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OECD FORD obor

10308 - Astronomy (including astrophysics,space science)

Projekt

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Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2019

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Observatory

ISSN

0029-7704

e-ISSN

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Svazek periodika

139

Číslo periodika v rámci svazku

1273

Stát vydavatele periodika

GB - Spojené království Velké Británie a Severního Irska

Počet stran výsledku

6

Strana od-do

231-236

Kód UT WoS článku

000496138800002

EID výsledku v databázi Scopus

2-s2.0-85076975850