# Polar plot for the event horizon of a Kerr BH

1. Apr 25, 2017

### Sumarna

I have made graph of event horizon of Kerr black hole by giving simple command of polar plot. The problem is that the point where the event horizon and static limit meets should be along y-axis but instead its on x-axis. I have tried everything but not getting it right.

What mistake I am making? Am i giving wrong command? I do not want it in 3D.

M = 1;
a = .7;
p1 = PolarPlot[-M + Sqrt[M^2 - a^2 (Cos[\[Theta]])^2], {\[Theta], 0,
2 \[Pi]}];
p2 = PolarPlot[-M - Sqrt[M^2 - a^2 (Cos[\[Theta]])^2], {\[Theta], 0,
2 \[Pi]}];
p3 = PolarPlot[-M - Sqrt[M^2 - a^2], {\[Theta], 0, 2 \[Pi]}];
p4 = PolarPlot[-M + Sqrt[M^2 - a^2], {\[Theta], 0, 2 \[Pi]}];
Show[p1, p2, p3, p4]

2. Apr 30, 2017

### PF_Help_Bot

Thanks for the thread! This is an automated courtesy bump. Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post? The more details the better.

3. Jun 20, 2017

### Yukterez

Just use the Sine instead of the Cosine: