The most general asymptotically flat, stationary solution of the Einstein–Maxwell equations in general relativity that describes the spacetime geometry in the region surrounding an electrically charged, rotating mass. It generalises the Kerr metric by taking into account the field energy of an electromagnetic field, in addition to describing rotation.
Questions tagged [kerr-newman-metric]
37 questions
17
votes
2 answers
If a Kerr-Newman black hole is like a charged, spinning, heavy magnet, what kind of magnet is it like?
I was reading up on De Sitter spaces, which states that the gravitational effects from a black hole is indistinguishable from any other spherically symmetric mass distribution. This makes a lot of sense to me.
I'm now super curious, can we just…
Alan Rominger
- 21,318
7
votes
2 answers
Escape velocity from a rotating black hole
Under Newton, the escape velocity is
$$v_{esc} = \rm c \ \sqrt{r_s/r}$$
where $\rm r_s=2 \ GM/c^2$. In the nonrotating relativistic case (the Schwarzschild case) the radial escape velocity is the same:
$$v^{\parallel}_{esc} = \rm c \…
Yukterez
- 14,655
7
votes
1 answer
Charged versus rotating black holes as different kinds of wormholes
I've heard that a maximally extended charged black hole can be a traversable wormhole to the same universe whereas a maximally extended uncharged rotating black hole can only be a wormhole to different exteriors that are merely isometric regions of…
Timaeus
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5
votes
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How to find the Hawking temperature for this metric?
I am reading this paper about "Hawking radiation of Kerr-Newman-de Sitter black hole", where the authors find Hawking temperature of this metric
The authors state that hawking temperature is given by
The problem is I am not sure how gives . I…
WhyME
- 265
4
votes
0 answers
Would a rotating charged black hole have a magnetic field? (Unrelated to the accretion disc)
In this question, the general consensus is that a charged black hole does have an associated electric field, due to the charges that have at some point gone inside (since their retarded potentials existed before the black hole did).
Now, if the…
agaminon
- 4,386
4
votes
1 answer
Visualizing vector fields lines in Kerr Newman
I want to visualise an test EM field in Kerr spacetime (I want to plot the integral field lines). The field is a test field in the sense, that it doesn't change the background (metric).
Could anyone point me to some more technical literature or some…
Nitaa a
- 290
4
votes
1 answer
Area of Kerr-Newman event horizon
I want to calculate the area of event horizon for a Kerr-Newman black hole by using boyer's coordinates.
I searched a lot from web, but I could not find any information about calculating event horizon radius for kerr newman. Can anyone help me to…
Ali Oz
- 63
4
votes
2 answers
Equation of motion for a charged particle
To compute the equations of motion of a neutral testparticle in the graviational field, one needs the metric tensor $g_{\mu \nu}$ and $g^{\mu \nu}$ to compute the Christoffel-symbols
$${\Gamma^{\rm i}_{\rm j k} = \sum _{\rm s=1}^4 \…
Yukterez
- 14,655
4
votes
1 answer
Correlation between gravitational and electromagnetic radiation from collision of Kerr-Newman black holes
When black holes collide, they produce a gravitational wave, as has been recently established by LIGO.
When a charge is accelerated, it creates an electromagnetic wave.
Does an accelerated massive charge, such as a Reissner-Nordstrom black hole,…
A. Ok
- 683
4
votes
2 answers
Explain Kerr-Newmann Black Hole Spins in SI Units
I'm trying to run some calculations on Kerr-Newman black holes, but I'm having two major difficulties. First, most equations I've been able to find are only for Kerr black holes. Second, essentially all equations are in one of several incompatible…
geometrian
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3
votes
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What is Kerr doing here?
On pages 19-20 of Kerr's conference about how he discovered his metric, he basically performs several coordinate transformations until reaching:
$$ds^2 = dx^2 + dy^2 + dz^2 - dt^2 + \dfrac{2mr^3}{r^4 + a^2z^2}[dt + \dfrac{z}{r}dz \\ + \dfrac{r}{r^2…
Antoniou
- 870
3
votes
2 answers
Are metrics of general relativity tested?
We tested general relativity with effects as gravitational lensing and existence of black holes (Schwarzschild metric). But there are other metrics, e.g. Kerr-Newman metric for a point mass with charge and angular momentum.
Have we tested such…
JavaGamesJAR
- 955
3
votes
1 answer
Metric diameter of a ring singularity
In the Kerr metric the ring singularity is located at the coordinate radius $r=0$, which corresponds to a ring with the cartesian radius $R=a$.
So the center of the ring singularity in cartesian coordinates is at $r=-a, \ \theta=\pi/2$.
But the…
Yukterez
- 14,655
2
votes
1 answer
Surface gravity for a rotating charged black hole
I have that the surface gravity (at the outer event horizon) for a Kerr-Newman black hole is
$$
K_+ = \frac{r_+-r_-}{2(r_+^2+(J/M)^2)} = \frac{\sqrt{M^2-Q^2-J^2/M^2}}{2M^2-Q^2+2M\sqrt{M^2-Q^2-J^2/M^2}}
$$
where $r_\pm$ are the outer and inner event…
Charles
- 766
2
votes
1 answer
Carter Constant with a Cosmological Constant
The Carter constant for the Kerr Newman metric
$$ \rm C = p_{\theta}^{2} + \cos^{2}\theta \ \Bigg[ a^2 \ (m^2 - E^2) + \left(\frac{L_z}{\sin\theta} \right)^{2} \Bigg] $$
with (in $[+---]$ signature)
$${{\rm E = -p_t}=g_{\rm tt} \ {\rm…
Yukterez
- 14,655