APOD: Swirling Magnetic Field around Our... (2024 Apr 01)

[APOD Robot]

Swirling Magnetic Field around Our Galaxy's Central Black Hole

Explanation: What's happening to the big black hole in the center of our galaxy? It is sucking in matter from a swirling disk -- a disk that is magnetized, it has now been confirmed. Specifically, the black hole's accretion disk has recently been seen to emit polarized light, radiation frequently associated with a magnetized source. Pictured here is a close-up of Sgr A*, our Galaxy's central black hole, taken by radio telescopes around the world participating in the Event Horizon Telescope (EHT) Collaboration. Superposed are illustrative curved lines indicating polarized light likely emitted from swirling magnetized gas that will soon fall into the 4+ million mass central black hole. The central part of this image is likely dark because little light-emitting gas is visible between us and the dark event horizon of the black hole. Continued EHT monitoring of this and M87's central black hole may yield new clues about the gravity of black holes and how infalling matter creates disks and jets.

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[Petr Bradfgrd]

Can anybody tell me the date this APOD was posted?

[Rauf]

Can anybody tell me the date this APOD was posted?

If I'm not mistaken, this is the first time that this APOD has been posted.

[Ann]

Can anybody tell me the date this APOD was posted?

If I'm not mistaken, this is the first time that this APOD has been posted.

The first time this picture was posted here at Starship Asterisk* was in the Found Images thread a few days ago. It has not been an APOD before, because the image was only recently released by the Event Horizon Telescope.

Ann

[Don Birren]

I look forward to reading APOD every April Fools Day. What happened, guys?

[Guest]

Why is it possible to See the „black“ of the black whole , when - in our view - light from the sucked Stars only is around the whole And Not in Front. In my opinion the black whole has completely endlosen with light…

[Ann]

I look forward to reading APOD every April Fools Day. What happened, guys?

Want more "The Moon is made of green cheese" jokes? I've only got that one.

The Moon is made of green cheese. Credit: I don't know.

---

Jason Major of lightsinthedark.com wrote:

Way back in 1546 ye olde English playwright and poet John Heywood wrote:

Ye fetch circumquaques to make me believe,
Or thinke, that the moone is made of greene cheese.
And when ye have made me a lout in all these,
It seemeth ye would make me goe to bed at noone.

The green cheese joke about Mars is old, so we need something fresher (but just as smelly). How about, Astronomers find that Mars is really a dried-out pizza with some disgusting toppings?

Wait, maybe it is Io, innermost large moon of Jupiter, that is the real pizza in the sky?

Mars as a pizza. Credit: Mars Express.

---

Jupiter chowing down on Io? Credit: I don't know.

---

Ann

[Marially]

What happened to the witty APOD images for April Fools Day? I miss those. There wasn't one last year either.

[Guest]

If this is the accretion disk, wouldn't it be parallel to the galaxy and since we are in the galaxy, wouldn't this view be impossible to see? So then in contrast to what they say, this is not a photo. Am I wrong?

[Don Birren]

What happened to the witty APOD images for April Fools Day? I miss those. There wasn't one last year either.

Huh. I didn't realize there wasn't one last year. Pooh. The only constant is change.

[Christian G.]

Fascinating APOD! But to me also frustrating! As yet again we are studying what surrounds a black hole, not what is inside. I would love to pick the brains of astrophysicists on this, I know they don't like to make claims unsupported by evidence but surely they must have opinions or hunches on the state of matter inside a black hole. And knowing that we will NEVER retrieve data from inside a black hole by sending probes in there, we need to hear those hunches and opinions! Knowing that they are only hunches of course.

In the case of a white dwarf, matter is compacted to the point where electrons occupy all available "space" around the nucleus and no extra electron is allowed; then neutron stars run over this "law" and electrons get pushed straight inside the nucleus and you are basically left with a 20 km wide nucleus or pack of neutrons, - and then what happens when that too gets crushed? You get a pack of deconfined quarks? And when those too get crushed, what do you get?

It does not make much sense to say that matter gets squashed out of existence and only leaves behind its gravity emerging from a volumeless point, like the Cheshire cat disappearing and leaving behind only its smile (to use John Wheeler's fun image about black holes).
I read wild speculations on worm holes punching through spacetime from the center of black holes to whatever destination inside our universe or even other universes, but little speculations on the residual matter or "kernel" of a black hole. Again, I get that we likely will never know for sure, but nonetheless, what can be said tentatively?

[Chris Peterson]

If this is the accretion disk, wouldn't it be parallel to the galaxy and since we are in the galaxy, wouldn't this view be impossible to see? So then in contrast to what they say, this is not a photo. Am I wrong?

There is no requirement that a galaxy's central black hole must share its axis of rotation (and therefore plane of any accretion disk) with that of its parent galaxy.

[Astronymus]

Why is it possible to See the „black“ of the black whole , when - in our view - light from the sucked Stars only is around the whole And Not in Front. In my opinion the black whole has completely endlosen with light…

It's an image of the radio band. It's not an actual photo. It like making infrasound audible.

[Ann]

I have nothing to say about the magnetic lines in today's APOD, but there is a video that explains why the black hole images (minus the magnetic lines) look the way they do.

Click to play embedded YouTube video.

I found the video kind of hard to understand, but then, I'm a math idiot. But even to me, it was somewhat clarifying.

Ann

[Chris Peterson]

I have nothing to say about the magnetic lines in today's APOD, but there is a video that explains why the black hole images (minus the magnetic lines) look the way they do.

Minor nit. The lines indicate polarization of electromagnetic radiation. This is most likely a proxy for magnetic fields.

[Bird_Man]

If this is the accretion disk, wouldn't it be parallel to the galaxy and since we are in the galaxy, wouldn't this view be impossible to see? So then in contrast to what they say, this is not a photo. Am I wrong?

The video, that Ann posted, does an excellent job of expelling why we will see the accretion disk from almost any angle we view the black hole. Very interesting.

[johnnydeep]

I have nothing to say about the magnetic lines in today's APOD, but there is a video that explains why the black hole images (minus the magnetic lines) look the way they do.

Minor nit. The lines indicate polarization of electromagnetic radiation. This is most likely a proxy for magnetic fields.

So if the accretion disk can be seen perpendicularly to the line of sight from any angle (as other posts of videos point out), and we're viewing the magnetic field lines in the accretion disk in this APOD image in that same perpendicular/face-on way, what is the overall form of the magnetic field of the BH as a whole? Does it have one? And would it be anything like the torus/doughnut shape of the magnetic field of the Earth or Sun (though granted the Sun's magnetic field lines get completely mangled the closer in to the Sun's surface and center you go!)?

[Chris Peterson]

I have nothing to say about the magnetic lines in today's APOD, but there is a video that explains why the black hole images (minus the magnetic lines) look the way they do.

Minor nit. The lines indicate polarization of electromagnetic radiation. This is most likely a proxy for magnetic fields.

So if the accretion disk can be seen perpendicularly to the line of sight from any angle (as other posts of videos point out), and we're viewing the magnetic field lines in the accretion disk in this APOD image in that same perpendicular/face-on way, what is the overall form of the magnetic field of the BH as a whole? Does it have one? And would it be anything like the torus/doughnut shape of the magnetic field of the Earth or Sun (though granted the Sun's magnetic field lines get completely mangled the closer in to the Sun's surface and center you go!)?

I can't answer as to what the field looks like. But as noted above, the accretion disk looks similar from most observation directions, and we don't really know what the inclination of Sgr A* even is. Best estimate is inclined 60° to the galaxy or 30° to the ecliptic, but there's a range of tens of degrees either way on that estimate.

Also, I think the general view is that black holes don't have magnetic fields (this is related to the no-hair theorem). The magnetic field under examination here is created by magnetized material falling inward. That is, the magnetic field around a black hole is a product of the dynamics of any accretion disk, not the black hole itself.

[johnnydeep]

Minor nit. The lines indicate polarization of electromagnetic radiation. This is most likely a proxy for magnetic fields.

So if the accretion disk can be seen perpendicularly to the line of sight from any angle (as other posts of videos point out), and we're viewing the magnetic field lines in the accretion disk in this APOD image in that same perpendicular/face-on way, what is the overall form of the magnetic field of the BH as a whole? Does it have one? And would it be anything like the torus/doughnut shape of the magnetic field of the Earth or Sun (though granted the Sun's magnetic field lines get completely mangled the closer in to the Sun's surface and center you go!)?

I can't answer as to what the field looks like. But as noted above, the accretion disk looks similar from most observation directions, and we don't really know what the inclination of Sgr A* even is. Best estimate is inclined 60° to the galaxy or 30° to the ecliptic, but there's a range of tens of degrees either way on that estimate.

Also, I think the general view is that black holes don't have magnetic fields (this is related to the no-hair theorem). The magnetic field under examination here is created by magnetized material falling inward. That is, the magnetic field around a black hole is a product of the dynamics of any accretion disk, not the black hole itself.

Ok. What's confusing here then is that assuming this imaging of the magnetic field lines would look the same from any angle - and it looks pretty non randomly flowing here! - then what does that say about the magnetic field as a whole? Too bad we don't have a near by BH to send a probe to to find out.

[darksky2500@gmail.com]

I'm trying to find info on the angular size of this view of SagA*. E.g., what is the field of view of the image??

The linked site says 10 microarcseconds (which sounds reasonable) but that's an old reference to previous imaging, not this new image with polarization info.

https://www.jpl.nasa.gov/edu/news/2022/ ... lack-hole/

[Chris Peterson]

So if the accretion disk can be seen perpendicularly to the line of sight from any angle (as other posts of videos point out), and we're viewing the magnetic field lines in the accretion disk in this APOD image in that same perpendicular/face-on way, what is the overall form of the magnetic field of the BH as a whole? Does it have one? And would it be anything like the torus/doughnut shape of the magnetic field of the Earth or Sun (though granted the Sun's magnetic field lines get completely mangled the closer in to the Sun's surface and center you go!)?

I can't answer as to what the field looks like. But as noted above, the accretion disk looks similar from most observation directions, and we don't really know what the inclination of Sgr A* even is. Best estimate is inclined 60° to the galaxy or 30° to the ecliptic, but there's a range of tens of degrees either way on that estimate.

Also, I think the general view is that black holes don't have magnetic fields (this is related to the no-hair theorem). The magnetic field under examination here is created by magnetized material falling inward. That is, the magnetic field around a black hole is a product of the dynamics of any accretion disk, not the black hole itself.

Ok. What's confusing here then is that assuming this imaging of the magnetic field lines would look the same from any angle - and it looks pretty non randomly flowing here! - then what does that say about the magnetic field as a whole? Too bad we don't have a near by BH to send a probe to to find out.

To be clear, the geometry of the accretion disk and of the magnetic field changes with orientation. It's just a product of the extreme curvature of space around the black hole that the appearance doesn't change much.

[johnnydeep]

I can't answer as to what the field looks like. But as noted above, the accretion disk looks similar from most observation directions, and we don't really know what the inclination of Sgr A* even is. Best estimate is inclined 60° to the galaxy or 30° to the ecliptic, but there's a range of tens of degrees either way on that estimate.

Also, I think the general view is that black holes don't have magnetic fields (this is related to the no-hair theorem). The magnetic field under examination here is created by magnetized material falling inward. That is, the magnetic field around a black hole is a product of the dynamics of any accretion disk, not the black hole itself.

Ok. What's confusing here then is that assuming this imaging of the magnetic field lines would look the same from any angle - and it looks pretty non randomly flowing here! - then what does that say about the magnetic field as a whole? Too bad we don't have a near by BH to send a probe to to find out.

To be clear, the geometry of the accretion disk and of the magnetic field changes with orientation. It's just a product of the extreme curvature of space around the black hole that the appearance doesn't change much.

So the accretion disk "looks" the same from any POV, yet the geometry of it (and presumably the matching magnetic field that we see here) would look different?

[Chris Peterson]

Ok. What's confusing here then is that assuming this imaging of the magnetic field lines would look the same from any angle - and it looks pretty non randomly flowing here! - then what does that say about the magnetic field as a whole? Too bad we don't have a near by BH to send a probe to to find out.

To be clear, the geometry of the accretion disk and of the magnetic field changes with orientation. It's just a product of the extreme curvature of space around the black hole that the appearance doesn't change much.

So the accretion disk "looks" the same from any POV, yet the geometry of it (and presumably the matching magnetic field that we see here) would look different?

Are different, despite the appearance after all the directions light travels have been distorted. That's my understanding.

[johnnydeep]

To be clear, the geometry of the accretion disk and of the magnetic field changes with orientation. It's just a product of the extreme curvature of space around the black hole that the appearance doesn't change much.

So the accretion disk "looks" the same from any POV, yet the geometry of it (and presumably the matching magnetic field that we see here) would look different?

Are different, despite the appearance after all the directions light travels have been distorted. That's my understanding.

Ok. My brain doesn't see it yet. Oh, and what of the nice symmetrical depiction of the magnetic field lines we see here: would it also look the same from any POV? (I may have missed that finer point above.)

[Chris Peterson]

So the accretion disk "looks" the same from any POV, yet the geometry of it (and presumably the matching magnetic field that we see here) would look different?

Are different, despite the appearance after all the directions light travels have been distorted. That's my understanding.

Ok. My brain doesn't see it yet. Oh, and what of the nice symmetrical depiction of the magnetic field lines we see here: would it also look the same from any POV? (I may have missed that finer point above.)

Well, since what we're actually seeing is a pattern of polarization in the same EM radiation that is being shown here as the disk, I would assume that the spacetime distortion that "lenses" the accretion disk so it looks similar from different angles applies to it as well. But this is far from my area of expertise!