See query.
So many radio astronomy images are false colored from their gathered spectra, naturally enough, to simulate visible light frequencies.
In this will-be-forever iconic image, what are we looking at stuck to (?) or circling (?–no idea which planes are known) the event horizon?
Data from eight arrays of radio telescopes collected data. [ . . . ] and four imaging teams previously tested their algorithms on other astrophysical objects, making sure that their techniques would produce an accurate visual representation of the radio data.
Generally frequency substitution algorithms trying to simulate visual processes for sub millimeter microwave radiation as it would look to an “eye” able to see it. The dark area is larger than our solar system.
Tris.
check out todays XKCD xkcd: M87 Black Hole Size Comparison
Good description here:
Try these for a nice set of explanations.
https://www.youtube.com/watch?v=zUyH3XhpLToWhat I don’t quite get is why the centre is dark. Black holes are basically spherical, aren’t they? In which case shouldn’t the glowing gas be all around it, including “in front” of the dark bit, from our perspective?
Good explanation here: The first image of the event horizon of a black hole, via the Event Horizon Telescope | SYFY WIRE
Brian
I presume we’re seeing the black hole as it looked 55 million years ago. Would it look different now after all this time? Much bigger? Smaller? Could it have gone completely? Do black holes ever die?
Black holes slowly “evaporate”. They release energy, called Hawking radiation (named for Stephen Hawking, who theorized its existence in the 1970s).
For a large black hole, the time required for it to evaporate completely would be significantly longer than the current age of the universe.
It will be very, very slightly bigger (but nothing that we could notice) from in-falling matter increasing its mass. The ring may be brighter or dimmer or about the same–it depends on how much material there is feeding it at any given time. It will “go away completely”–in about 10 billion billion billion billion billion billion billion billion billion times the current age of the universe. (That number isn’t being facetious–according to theory a supermassive black hole will take around 1x10[sup]100[/sup] years to evaporate.)
So, regardless of where the viewer is in space, the picture would look the same?
Depending on where the observer is, in relation to the accretion disk, certain parts will be brighter.
The overall form of the image would be the same? A ring of varying brightness around a central void?
Watch the first video in the post by Francis Vaughan. About 1:30 in there is a simulation of how it would look in various orientations. But for the most part the theory is that it will look like a ring with one edge being brighter than the other.
First of all, while the black whole is spherical, the glowing material isn’t. It’s gathered in the accretion disc, and thus mostly … disc shaped.
But even if it was a sphere, the middle would be a lot less bright than the edges. Maybe enough so that the middle wouldn’t stand out against the background of being in the center of a galaxy.
Imagine looking at a glowing shell around a black sphere. The edges will have much more glowing gas in your line of sight than the middle. Adding to that is the bending of light by the black whole, which will not be sending any light towards us from the middle.
Taking the hole’s mass to be 6.5 billion solar masses, I find a lifespan of either 5.910^95 years, 1.0010^96 years, or 3.2*10^96 years, depending on a few unknown details of neutrino physics (I think the largest of those three is the most likely to be correct).
As a nit-picky aside (though aldiboronti hasn’t said anything wrong and asked great questions), for all intents and purposes what the black hole looks like “now” for us is when its light reaches earth.
Thanks to the cosmic speed limit, referring to what it would look like “now” if we traveled there to see it close up means traveling through space-time, so “now” no longer has the same meaning. And of course traveling close to c brings in all the relativistic effects, so in addition to taking 55 million plus years to get there to see what it looks “for reals”, not only won’t you be seeing what it looks like now, the black hole and earth will have aged well beyond that anyways.
Instantaneously traveling there is a great thought experiment (and helpful for explaining why, for example, far-distant galaxies look younger or addressing aldiboronti interesting questions), but it kinda involves magical thinking to actually do that which is why I get all pendantic-y when someone says we’re not seeing some celestial object as it is “now” (again, aldiboronti didn’t do that).
I believe the question as equal meaning if say we took a time machine trip back 55 million years on earth and asked what the black hole looked like from earth then. Certainly no one would say the results are what the black hole looked like “now”.
Wow, I droned on way too long. Corrections and thoughts appreciated!
Does nobody else find it fascinating that the first picture of a black hole is one that is facing almost directly towards Earth? Or would that be expected?
Going to make a guess, that as a BH will have an orientation, that they sought one that would have a high probability of “facing” us in this manner.
That “ring” is going to be more like a torus vs what we’d see with Jupiter and it’s rings?
They are also working on “our own” Milky Way black hole, Sagittarius A*, which we presumably see edge on, being in the disc of the galaxy and all.