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Astronomers reveal first image of the black hole at the heart of our galaxy

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Re: Astronomers reveal first image of the black hole at the heart of our galaxy

#161

Post by JonShartwell »

malfist wrote: post #36
fasteddie31003 wrote: post #29

I am very skeptical of the Event Horizon Telescope (EHT) images because they are not following a scientific method that results in a true representative image of their target. In my opinion astronomy is jumping the shark with these images by making this a big PR stunt. I've looked at their methods for their earlier images and they seem to be hunting for a circle that looks like a black hole in their data. The EHT's f…

Why do you think you know more about astronomy than a team of scientists publishing peer reviewed information?

It’s absolutely in the spirit of science to question an experiment’s methods and results. If you disagree with the criticism then present some evidence. An appeal to authority is pretty unconvincing considering scientists have been confidently wrong about quite a lot in the past.

Re: Astronomers reveal first image of the black hole at the heart of our galaxy

#162

Post by jepler »

ramigb wrote: post #148

Can the smart people in here confirm if we are getting sucked into this someday or not?

On the timescale from now until the sun goes nova, confident "no".

Roughly speaking, the sun orbits the galactic center at a velocity of 220km/s. To fall into, or to be sucked into, the central black hole would require the loss of all this velocity, which means applying acceleration to the sun opposite the direction of its orbit. Lots of acceleration. That has to come from somewhere.

I suppose there's some extremely tiny amount of drag that occurs due to the sun moving in the interstellar medium, but aside from that there's not a lot that applies acceleration to the sun opposite the direction of its orbit. Really the only other thing that comes to mind are the gravitational waves that are radiated by co-rotating objects. This is the effect that causes close by black holes to eventually come close enough that they merge. But in objects traveling at slower speeds in larger orbits, this effect is also negligible on the scale of billions of years. (These are the gravitational waves observed by LIGO). https://en.wikipedia.org/wiki/Two-body_problem_in_general_re...

Re: Astronomers reveal first image of the black hole at the heart of our galaxy

#164

Post by dekhn »

hammock wrote: post #155
fsh wrote: post #125

Earlier quoted context omitted.

The resolution of these telescopes is limited by diffraction, not by the number of pixels on the sensors. The achievable angular resolution is roughly the wavelength divided by the aperture diameter [1]. JWST works in the few µm wavelength range and has a 6.5 m aperture, such that the angular resolution is ~0.1 arcsec. The EHT works with 1.3 mm wavelength and has an effective aperture of roughly the earth diameter (~…

Should have clarified. Does a black hole have fuzzy edges or sharp edges?

this is sort of getting into the definition of black holes and event horizons. I don't think they really have solid surfaces, I would expect all imaging here to show fuzzy samples.

Re: Astronomers reveal first image of the black hole at the heart of our galaxy

#165

Post by wnevets »

wthomp wrote: post #91

For those wondering if we could get sharper images with JWST, here’s the previously imaged black hole (same angular size as our own) compared to a single pixel from Hubble’s wide field camera 3: https://twitter.com/alex_parker/status/1116070667068170240?s... JWST will have smaller “pixels” but is in the same ballpark.

That really puts the significance of this new image into perspective.

Re: Astronomers reveal first image of the black hole at the heart of our galaxy

#166

Post by dekhn »

raattgift wrote: post #64
kloch wrote: post #10

One of the findings they announced at the press conference is that the spin of the black hole is not aligned with the galactic plane but is tilted "towards us" so that it is viewed face on. How unexpected is that?

For a small-mass central black hole (CBH), the spin-spin coupling of the CBH and the bulk matter of a relatively small and sparse galaxy is so small that it the orientation of the spin axis is almost unconstrained. That from Earth we look down on the CBH's north pole (right-hand-rule: the bright features appear to circulate counter-clockwise, and there is decent evidence in them that the black hole's spin is in the s…

when you say spin-spin coupling, do you mean exchange of momentum between the spin of the black hole and the spin of the galaxy that contains it? I normally think of spin-spin in terms of atomic/subatomic particles (https://en.wikipedia.org/wiki/J-coupling)

Re: Astronomers reveal first image of the black hole at the heart of our galaxy

#167

Post by DiogenesKynikos »

fasteddie31003 wrote: post #141
malfist wrote: post #137

Earlier quoted context omitted.

You realize peer review isn't just something you do and they automatically publish you, right? Peer review makes sure your science is sound. But I'm sure you're more of an expert than anybody serving in a peer review board.

Peer review has let plenty of bad science through. Don't burn me at the stake because I speak heresy against the holy theologians of astronomy.

Bad papers do get through, but anything as high-profile as the first image of the supermassive black hole at the center of the Milky Way will get intense scrutiny.

Re: Astronomers reveal first image of the black hole at the heart of our galaxy

#168

Post by coryfklein »

I'm sorry, I am really confused. Didn't we get "the first picture of the black hole at the center of our galaxy" like 2-3 years ago? I definitely remember seeing a nearly identical photo, and lots of press coverage about a particularly young woman who was closely involved in the project. What that something different?

Re: Astronomers reveal first image of the black hole at the heart of our galaxy

#169

Post by GoblinSlayer »

markus_zhang wrote: post #19
adgjlsfhk1 wrote: post #17

Earlier quoted context omitted.

GR and quantum field theory don't work together, so at least one of them is wrong, and it would be good to figure out which and how.

Thanks. Can you please point me to some popular science article that explains why the two do not agree with each other?

tl;dr they don't conflict with each other, they conflict with a third assumption that particles have zero size. GR suggests they would be black holes, and those have mathematical difficulties. String theory is an attempt to model particles of finite size and thus eliminate black holes.

Re: Astronomers reveal first image of the black hole at the heart of our galaxy

#170

Post by DiogenesKynikos »

Sporktacular wrote: post #99
kloch wrote: post #97

Earlier quoted context omitted.

They collected data on both back in 2017. It took until now to develop the image processing techniques to account for the rapid changes in the accretion disk around Sag.A*.

Ah, so they didn't release an image of it back then? Or was it just a less precise image? Thought I saw one but can't find it now among all these newly release images. Thanks BTW

They only released the image of M87 back then.
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