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Black Hole Hunters

nytimes.com

30 pointsdavesque9 comments

Is it not possible to look at the accretion disk with a telescope and then make the calculations for the Event Horizon radius (Schwartzchild radius), etc of the black hole? Or do some black holes not have accretion disks?

Our best bet is viewing the one at the center of the milky way and so far we haven't seen it. They are caused by infalling matter and currently not much is falling in. So at least for now it's easier to look at the jets coming out of more distant black holes.

Not in the optical if that's what you mean, and not in most of the rest of the spectrum, there's a lot of dust between us and Sgr A*.

But looking at the accretion disk is exactly what the EHT is doing, just in microwaves since those can be seen clearly trough the dust.

Very exciting to see the EHT taking data again!

Too bad it sounds like they didn't get a great run, but hopefully they got enough baselines to combine with the old data and get a picture! :DDD

Imaging the event horizon of a black hole would be a watershed moment. I really want to see this happen.

But you can only image millimeters before it, right? It still wouldn't show what happens at the event horizon, would it? Or am I wrong? (Armchair physicist as best, so correct me where I'm wrong, please.)

Sure, but we've not seen an acretion disk so far, only the resulting jets. But by definition we can only see up to the event horizon, not the horizon itself or beyond.

You can't see the edge of the event horizon either - time is stopped at such a place. And slightly farther away events happen so slowly they are invisible at human time scales.

Even far from a black hole it would be almost impossible see anything. All the light would be red shifted to invisibility (because of the intense gravitational field), and the brightness would be very low because it's happening so slowly.

I suspect that some of the very red, very dim, galaxies that are assumed to be very distant because they are hubble-red-shifted so much, are actually super-massive objects.

It's probably true that you wouldn't be imaging the event horizon itself for various reasons. I just mean it would be amazing to peer into the vicinity of a suspected black hole and see, as theory would predict, a black spot along with an accretion disc.

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