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12 votes
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Why is the ring in this simulation of Sgr A* off center?

The photon ring around a non-spinning Schwarzschild black hole is perfectly circular and centered on the black hole. The photon ring around a spinning Kerr black hole is almost circular (except for ...
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6 votes

Why is the ring in this simulation of Sgr A* off center?

The folder with the video this image comes from has a google docs document with captions and credits. The caption for this video reads "A video demonstrating the effect of inclination on the ...
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5 votes

Why doesn't the black hole in the center of the Milky Way glow similarly to the famous M87 image?

News were released today and a new image has been published which has similarities to the M87 image in the question. https://eventhorizontelescope.org/blog/astronomers-reveal-first-image-black-hole-...
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6 votes

Difference between NSBH and BHNS mergers

Both articles are referring to the detection of gravitational wave sources where one component is of low enough mass to be considered a likely neutron star, whereas the other is more massive, and too ...
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7 votes
Accepted

Black hole magnification factor

I'd suggest you take a look at Narayan and Bartelmann (1996). They run through all the math to answer exactly this question. I'll add here the punchline from their paper for posterity. Shown below is ...
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10 votes

Is a black hole really a neutron star with a gravitational time dilation factor of 1.0

I'm not sure what you mean by gravitational length contraction, and the time dilation formula you are using is only approximately correct for weak gravitational fields. Observed neutron stars are ...
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5 votes

Using Einsteinpy to plot the precession of a star orbiting a black hole?

This is an interesting development, thanks for bringing it to our (my) attention. Unfortunately, the documentation is lagging the code. The package is using natural, geometrised units, where $G=c=1$ ...
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2 votes

Why are pseudo-Newtonian potentials used in studies of accretion processes around black holes?

What is $V_\mathrm{eff}$? The effective potential from S&T isn't the gravitational potential, $V$, that appears in places like $\vec{F}_g = -m \nabla V$. That effective potential comes from a ...
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17 votes
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Doubt regarding size and shape of black hole images published by the Event Horizon Telescope (EHT)

The detail you seek is contained in Johansson (2014). The photon ring around a black hole is not the event horizon. It is the projection of unstable photon orbits that are able to loop around the ...
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