Stargazing Event Horizon Telescope Results Released Yesterday (April 10, 2019)

[davenn]

An obvious way to get more baseline for VLBI is to go into outer space, but not many radio-astronomy satellites have been launched, satellites like HALCA and Spektr-R.

well there is a much easier way and it doesn't involve the massive cost of space based scopes and it also gives a massive VLBI
... namely observations 6 months apart on opposite sides of the Earth's orbit, an approx 300 million km baseline D

 

[websterling]

The observations have to be simultaneous for this to work.

 

[PAllen]

The observations have to be simultaneous for this to work.

I assumed the smiley meant @davenn was well aware of this.

 

[davenn]

The observations have to be simultaneous for this to work.

I assumed the smiley meant @davenn was well aware of this.

Actually, they don't, the data can be collected with good timing and then sync'ed once all data is collected
this is just the same for the Earth based radio telescopes that were involved in the M87 observations

NOT ALL of them could see M87 at the same time ... as we don't live on a flat earth, simultaneous obs's are impossibleDave

 

[mfb]

You cannot use that baseline for VLBI in the way the Event Horizon telescope did if you take the data 6 months apart. You need to record the same waveforms at multiple places to do interferometry.

NOT ALL of them could see M87 at the same time

But always more than one when they took data, otherwise recording data would have been pointless.

Independent of the physics: Think about it for a second. Would they have made an image with a <10,000 km baseline if there was a way to get a baseline 30,000 times longer with the same telescopes?

 

[davenn]

You cannot use that baseline for VLBI in the way the Event Horizon telescope did if you take the data 6 months apart. You need to record the same waveforms at multiple places to do interferometry.

But always more than one when they took data, otherwise recording data would have been pointless.

and there you just contradicted yourself
6 hours or 6 months, don't make any difference and there would still be more than one observing at the 6 months apartD

 

[mfb]

and there you just contradicted yourself

No I didn't. Maybe you misread my post?
You need simultaneous observations. 6 hours time difference between telescopes would ruin it in the same way 6 months do. The Event Horizon Telescope only used data where at least two telescopes could observe at the same time - more are better.

 

[Orodruin]

6 hours time difference between telescopes would ruin it in the same way 6 months do.

Depending on the distance between the telescopes ...
The point is that you need to observe the same wave front. That is how you do interferometry.

 

[websterling]

well there is a much easier way and it doesn't involve the massive cost of space based scopes and it also gives a massive VLBI
... namely observations 6 months apart on opposite sides of the Earth's orbit, an approx 300 million km baseline D

If it was this easy, it could have been done in the '70s, maybe even the '60s

 

[davenn]

If it was this easy, it could have been done in the '70s, maybe even the '60s

think about what you wrote
now think about the available technology at that time

so no, it couldn't have been done

 

[Zeke137]

The picture published by the EHT team is the result of months of observations of the black hole in M87, taken by several radio observatories, and then processed for several months afterwards by data-processing experts using supercomputers. The picture is not a photograph in the ordinary sense.

Note the use of radio observatories in collecting the data: no "glass" reflectors were used to collect visible light, but rather many radio telescopes with dishes made of metal to collect signals at millimeter radio wavelengths. Here's one of them, the ALMA array in the Atacama desert in Chile:

As @sysprog has mentioned, playing with brightness or contrast in the published picture will reveal no new data or information.

 

[Itsnotablackhole]

The picture published by the EHT team is the result of months of observations of the black hole in M87, taken by several radio observatories, and then processed for several months afterwards by data-processing experts using supercomputers. The picture is not a photograph in the ordinary sense.

Note the use of radio observatories in collecting the data: no "glass" reflectors were used to collect visible light, but rather many radio telescopes with dishes made of metal to collect signals at millimeter radio wavelengths. Here's one of them, the ALMA array in the Atacama desert in Chile:

View attachment 245385

As @sysprog has mentioned, playing with brightness or contrast in the published picture will reveal no new data or information.

Hi, that's a great photo, by the way, thank you for your reply, and sorry i don't mean to seem contentious, you are clearly clever people, I just want to discuss this more slowly, point by point, so we may get to the truth of this, first black hole photo, as I am fascinated, thanks,,,,you said firstly if this was an asteroid it would have moved very quickly in front of the star! ... my answer is, yes if it were moving left or right! But it could be moving towards us, in which case it would not have moved quickly in front of the star. ... All solid objects with an edge, are capable of lensing , I.e. light bends around the objects edge. ... ...By asteroid I mean rock, and we don't know it's size because we don't know it's distance. ... Playing with the max brightness, and adjusting viewing angle will reveal new information on normal digital optical photo's, but the first black hole photo was based on an algorithm of what has been seen, not what hasn't been seen. So I fear ambiguity, I.e. how does the algorithm know what a black hole looks like, maybe from the human imagination, I.e. physics theory simulations, but Einstein said we would not be able to see a black hole ... in 2017 and 2018, dark objects rocks? Asteroids? can be seen heading across m87 near where the first black hole photo is taken. Should these not be considered and or at least ruled out or in? Depending on periphery observations and timelines ?

 

[sysprog]

Hi, that's a great photo, by the way, thank you for your reply, and sorry i don't mean to seem contentious, you are clearly clever people, I just want to discuss this more slowly, point by point, so we may get to the truth of this, first black hole photo, as I am fascinated, thanks,,,,you said firstly if this was an asteroid it would have moved very quickly in front of the star! ... my answer is, yes if it were moving left or right! But it could be moving towards us, in which case it would not have moved quickly in front of the star. ... All solid objects with an edge, are capable of lensing , I.e. light bends around the objects edge. ... ...By asteroid I mean rock, and we don't know it's size because we don't know it's distance. ... Playing with the max brightness, and adjusting viewing angle will reveal new information on normal digital optical photo's, but the first black hole photo was based on an algorithm of what has been seen, not what hasn't been seen. So I fear ambiguity, I.e. how does the algorithm know what a black hole looks like, maybe from the human imagination, I.e. physics theory simulations, but Einstein said we would not be able to see a black hole ... in 2017 and 2018, dark objects rocks? Asteroids? can be seen heading across m87 near where the first black hole photo is taken. Should these not be considered and or at least ruled out or in? Depending on periphery observations and timelines ?

Please re-read what @Zeke137 said. Your wild speculations are completely outside the realm of the possibilities consistent with the first-rate research and reporting associated with the image being discussed. And please also break your ideas into paragraphs and re-examine them before posting them.

 

[Zeke137]

yes if it were moving left or right! But it could be moving towards us, in which case it would not have moved quickly in front of the star

You are ignoring or discounting the dynamics of objects in the solar system. All objects within the solar system are under the influence of the gravitational fields of all the other objects in the system, with the Sun and planets being the major contributors to gravitational influence.

Asteroids follow orbits around the Sun, and the velocities at which they travel are determined by their distance from the Sun, which is different than the Sun-Earth distance. It is not possible dynamically for an asteroid to be "moving toward us", except momentarily. It's a little like walking along a road, and an automobile passes us: it's close by for a short while, and then the automobile continues on its' journey, getting further away from us. The dynamics of the walker and the automobile are different, and they come close to each other for a short while only. If you were to watch asteroids through a telescope, you would notice them moving quite quickly through the star-field. The likelihood of an asteroid occluding any chosen star is very small, and the period of occlusion is also very small.

All solid objects with an edge, are capable of lensing , I.e. light bends around the objects edge

The effect you mention is known as diffraction, not lensing - see e.g. https://en.wikipedia.org/wiki/Diffraction . The sharper the diffracting edge, in terms of the light's frequency, the greater the degree of diffraction. Conversely, a more rounded edge diffracts to a lesser degree. Asteroids, generally quite rounded objects, would not cause any discernible diffraction.

Lensing, in the astrophysical sense of gravitational lensing, is caused by the "warping" of space-time around VERY massive objects, like stars, galaxies, or clusters of galaxies. An asteroid is just not massive enough, by a factor of many billions.

in 2017 and 2018, dark objects rocks? Asteroids? can be seen heading across m87 near where the first black hole photo is taken. Should these not be considered and or at least ruled out or in?

Again, the picture is not a photo! It has not been taken with a camera. It is the product of long-term data acquisition, analysis and processing, and has been produced by a computer. It is not a photo.

And again, the data were acquired by radio observatories, not by optical telescopes. A radio observatory simply does not, and cannot, "see" or observe asteroids, since asteroids do not emit EM radiation or light at radio frequencies. If an asteroid passed by the field of view of a radio observatory, it would be completely invisible to that observatory.

So your idea of asteroids or rocks causing features in the picture published by the EHT team are, frankly, completely without merit, and not tenable physically.

 

[sophiecentaur]

Should these not be considered and or at least ruled out or in?

Do you seriously think that stuff like that is not considered? More or less every observation in Astronomy is examined again and again before any conclusions are reached about its cause. Your suggested explanation is so 'alternative' (most polite word I can think of) that it would get considered for no more than a second. The Physics just does not fit.

It has already been pointed out that the motion of all celestial objects is such that no three objects can lie on a straight line (i.e. the same as a beam of light) for longer than an instant.

 

[Drakkith]

All solid objects with an edge, are capable of lensing , I.e. light bends around the objects edge.

No, that is entirely false. Solid, opaque objects do not bend light around themselves. The effect of diffraction isn't even a bending of the wavefront, it's an interference effect.

Playing with the max brightness, and adjusting viewing angle will reveal new information on normal digital optical photo's, but the first black hole photo was based on an algorithm of what has been seen, not what hasn't been seen.

I have no idea what this is supposed to mean.

So I fear ambiguity, I.e. how does the algorithm know what a black hole looks like, maybe from the human imagination, I.e. physics theory simulations,

It 'knows' because we know how radio waves behave and how to generate a real image using them. There is no ambiguity here. And note that a simulation based on physics theories is about as far from 'imagination', i.e. 'made up', as you can get.

but Einstein said we would not be able to see a black hole

We can't see the black hole. But we can see the accretion disk, which is what the image is showing. And it is distorted in just such a way as we would expect the black hole's gravity to do.

 

[sysprog]

... the motion of all celestial objects is such that no three objects can lie on a straight line (i.e. the same as a beam of light) for longer than an instant.

Could that statement be moderated a little? It seems to me to be an overstatement of something that as stated is almost, but not quite, true. I think that in principle it's possible that three emitted particles could lie along the same line for longer than an instant, a microsecond, or a second.

 

[Drakkith]

Could that statement be moderated a little? It seems to me to be an overstatement of something that as stated is almost, but not quite, true. I think that in principle it's possible that three emitted particles could lie along the same line for longer than an instant, a microsecond, or a second.

It's techically true since a line has no width, so three moving objects moving in different directions cannot stay along the same line for more than an instant. But in reality the movement between them could be slow enough for an object to block out a star for more than a second or two. It's just really, really unlikely since the orbits of the vast majority of objects in the solar system don't allow them to line up with Earth in this way. I.E. when the tangent line of Earth's orbit intersects an object, that object will almost certainly have some significant component of its velocity perpendicular to the line.

 

[sysprog]

It's techically true since a line has no width, so three moving objects moving in different directions cannot stay along the same line for more than an instant.

That would still be not only for an instant, but would instead be for as long as the size and speed and paths of concurrent line traversal of the objects allowed for them to remain co-aligned; however, the statement that I was suggesting might be more accurate if modified didn't include any provision that the objects had to be moving in different directions, and no-one has examined all celestial objects to ensure that no 3 objects ever move along the same line for longer than an instant, and even given that a line has only 1 dimension, three moving 3-dimensional objects could as far we know remain aligned along some line forever, or at least for a lot longer than an instant, however long that might be.

 

[pinball1970]

So does this count as the first direct detection of black holes?

I don't think anyone answered this so it is worth replying now the thread has sprang back to life.
I think this is the first direct observation although 'direct' and 'observation' have to be defined.
One can never directly observe a black hole only what comes out of it and how it affects it's neighbours orbits, stars.
The difference with these images (again definitions matter) the region around the event horizon has been illustrated adding colour to the radiation so one can see what is there.
I think that is the first you are referring to.

Edit. The guys can correct this where necessary. There is a great little video of stars moving in weird orbits due to a black hole but I cannot find it.
Edit 2. Found it.
https://www.eso.org/public/videos/eso1825e/First indirect? Conclusive?

 

[Drakkith]

and no-one has examined all celestial objects to ensure that no 3 objects ever move along the same line for longer than an instant, and even given that a line has only 1 dimension, three moving 3-dimensional objects could as far we know remain aligned along some line forever, or at least for a lot longer than an instant, however long that might be.

The problem is that all objects are moving around in orbits, which don't allow for such a situation to occur. Even three objects initially moving along the same line would immediately deviate from that line as soon as gravity started acting on them. (Assuming we mean that the line passes through the center of each object, not just that the line passes through the object at any location)

 

[Janus]

That would still be not only for an instant, but would instead be for as long as the size and speed and paths of concurrent line traversal of the objects allowed for them to remain co-aligned; however, the statement that I was suggesting might be more accurate if modified didn't include any provision that the objects had to be moving in different directions, and no-one has examined all celestial objects to ensure that no 3 objects ever move along the same line for longer than an instant, and even given that a line has only 1 dimension, three moving 3-dimensional objects could as far we know remain aligned along some line forever, or at least for a lot longer than an instant, however long that might be.

The problem is that all objects paths are determined by the effects of gravity and the laws of motion.
So for example, the Earth orbits the Sun in a (nearly) circular path. M87, the galaxy the telescopes were pointed at in in Virgo, so it pretty much is close to the orbital plane of the Earth. It is a distant galaxy, so the sight lines are for all practical purposes parallel, as represented by the white lines in this diagram.

This shows sight lines for a 6 month period. white lines are sightlines to M87 An asteroid in between us an m87 would be orbiting further out ( and with a longer orbital period). And while it could just be possible for it to align with the sight lines joining Earth and m87 at three points during that 6 mo period if it were at the exact right distance from the Sun, the rest of the time, it would not be, as shown by the red lines. The type of trajectory the asteroid can follow is limited by the laws of physics and there just isn't any such trajectory that would keep it perfectly in line between Earth and M87 for more than brief moments.

 

[DaveC426913]

Does anyone have any number on the total duration of exposure for this (radio) image?
Objects this distant are so faint they require long exposures just to get enough data.

Were this to be an alignment phenomena, such as an occultation by a dark body (one that would have to be a truly massive to create an Einsteinian Ring at all) it would have to stay aligned for the entire duration of all exposures.

And the brightness profile would be unique. As it passed into and out of alignment, we should see a partial ring before and after.

Also, we'd never see it again.

[ EDIT ] Oh. Duh. Six months duration.

 

[sysprog]

The problem is that all objects are moving around in orbits, which don't allow for such a situation to occur. Even three objects initially moving along the same line would immediately deviate from that line as soon as gravity started acting on them. (Assuming we mean that the line passes through the center of each object, not just that the line passes through the object at any location)

The statement to which I was taking mincing exception did not include your curative parenthetical restriction.

The problem is that all objects paths are determined by the effects of gravity and the laws of motion.
So for example, the Earth orbits the Sun in a (nearly) circular path. M87, the galaxy the telescopes were pointed at in in Virgo, so it pretty much is close to the orbital plane of the Earth. It is a distant galaxy, so the sight lines are for all practical purposes parallel, as represented by the white lines in this diagram.
View attachment 245404
This shows sight lines for a 6 month period. white lines are sightlines to M87 An asteroid in between us an m87 would be orbiting further out ( and with a longer orbital period). And while it could just be possible for it to align with the sight lines joining Earth and m87 at three points during that 6 mo period if it were at the exact right distance from the Sun, the rest of the time, it would not be, as shown by the red lines. The type of trajectory the asteroid can follow is limited by the laws of physics and there just isn't any such trajectory that would keep it perfectly in line between Earth and M87 for more than brief moments.

Thanks for that excellent illustration and explanation; please understand that I wasn't for a moment trying to argue that any possibility of occultation had anything to do with the M87 image. I opined that @sophiecentaur's statement that "... the motion of all celestial objects is such that no three objects can lie on a straight line (i.e. the same as a beam of light) for longer than an instant" was an overstatement of something that is almost, but not quite true. Sand falling in an hourglass can produce 3 moving grains lying along a straight line for longer than an instant.

 

[Borg]

And Why are there no objects, stars planets, space debris being sucked into the black hole? And accelerating towards the black hole?

Things have to get pretty close to get sucked in but we can see them orbiting.

This time-lapse video from the NACO instrument on ESO's Very Large Telescope in Chile shows stars orbiting the supermassive black hole that lies at the heart of the Milky Way over a period of nearly 20 years.

 

[Drakkith]

"NO" I don't think all of these things are considered. I think people make mistakes. I think that people see what they want to see,,,, they look for the result they want to see,,,,, and do not look for the truth, with an open mind.

Then you're living in a make-believe world where science and engineering don't produce useful results and technologies, and one where people are so inept and close minded that they can do their work everyday and produce nothing useful, yet still think that they did.

That's not how the real world works the overwhelming majority of the time. Scientists and engineers are, on the whole, extremely competent people who try very hard to avoid the exact mistakes you're accusing them of making.

like when you said it can't be an asteroid, (rock) because it would transit (pass) the star more quickly, but that all depends on the direction of the asteroid, (rock) ,,,,,,not all asteroids move left to right,, across the telescope image, ,,,some move towards or away from the observer, slowing a transit time.

This has already been discussed in several posts before this. Over the time period required to take the images the Earth moved halfway through its orbit. There is absolutely no way for an asteroid to keep itself between us and our target for anywhere close to that length of time. It is impossible in every sense of the word.

However, I think they are looking in the right place for the black hole, but they have not found it, they have just found a rock, so far.

This is nonsense. Our telescopes are not seeing radio waves bending around a rock. It's hard to overstate the difference between the image of the black hole and an image generated by looking at the diffraction of radio waves around an object. Scientists simply aren't going to confuse the two.

We are all learning from each other, so

Forgive me, but I don't feel that you're making a serious effort to learn anything here.

I would appreciate any insight as to why there is no swirl? On the edge of the black hole disc.

Why would there be?

And Why are there no objects, stars planets, space debris being sucked into the black hole? And accelerating towards the black hole?

Because black holes are not vacuum cleaners. They don't suck anything in. If the Sun collapsed into a black hole right now, the Earth and all the planets and other objects in the solar system would simply go about orbiting just as they always have. There would be essentially no change. None of them would be sucked into the new black hole.

In order for something to fall into a black hole, it has to lose enough energy to lowers its orbit to within a very close distance to the event horizon. Gas clouds do this by losing energy between collisions of gas atoms. The gas is heated because of these collisions and the energy is radiated away as EM radiation. This energy initially came from the energy the gas had in its orbit, so parts of the gas gradually fall closer and closer to the black hole as more and more energy is radiated away.

But with large objects like planets, there is rarely anything to interact with that can drop their orbits to the point needed to fall into a black hole.

 

[sysprog]

"NO" I don't think all of these things are considered. I think people make mistakes. I think that people see what they want to see,,,, they look for the result they want to see,,,,, and do not look for the truth, with an open mind.

Thanks for parsing your ideas into paragraphs this time.

I agree with nearly all of what @Borg and @Drakkith said; they posted while I was composing this post. I also agree with nearly all of what @sophiecentaur and other prior posters said in this thread.

Your third sentence looks to me as if you are saying something that would entail that the scientists who created and presented the M87 work and the commentary about it are not really honest enough to be scientists, but you've presented nothing in support of such a charge.

You say that these things are considered for no more than a second,

like when you said it can't be an asteroid, (rock) because it would transit (pass) the star more quickly, but that all depends on the direction of the asteroid, (rock) ,,,,,,not all asteroids move left to right,, across the telescope image, ,,,some move towards or away from the observer, slowing a transit time.

Are you using extra commas to indicate longer pauses? That's not necessary when you're writing things here on PF. The ideas are what matters.

I double check everything,

Some errors that might otherwise be missed can be caught that way.

Asteroids can travel in more directions than just left to right .

The observers of the radio-telescope arrays can reliably distinguish an asteroid inside the solar system from a supermassive object that is thousands of light-years away. It may be possible that the M87 object is "not a black hole", as your username appears to postulate, but it's not even remotely close to reasonable to suggest that it might be a local asteroid.

Maybe the entire problem, is, some don't spend a long enough time with the problems of what if?

Scientists spend a great deal of time pondering 'what if' questions; however, human lives are of limited duration, so everyone who ponders such questions must prioritize, in order to avoid spending too much time on thinking about things with too little likelihood of ever turning out to yield worthy insight.

However, I think they are looking in the right place for the black hole, but they have not found it, they have just found a rock, so far.

Please double-check that sentence. Apparently, you agree with the idea that there is a supermassive black hole somewhere near the center of the galaxy, and you agree that "they", i.e. people who are among our most competent and best equipped scientists, are "looking in the right place for the black hole", and yet you apparently think that their best efforts are susceptible to the error of mistaking an asteroid for it.

I want to see the real deal myself, as well, but I want to be sure it is the real deal.

I can relate.

There are many people who have serious doubts about the validity of the first black hole photo.

Do you have any sources that you can cite in support of that assertion?

We are all learning from each other, so

We're not all equals in that regard. Some of us know a great deal more than others about some things. I'm confident that many people know much more than I do about many things. Not only that, it is also apparent to me that some people here on PF are not only more knowledgeable in their subject areas than I am, but are also better at imagining and reasoning about them than I am.

I would appreciate any insight as to why there is no swirl? On the edge of the black hole disc.

And Why are there no objects, stars planets, space debris being sucked into the black hole? And accelerating towards the black hole?

I concur with the responses of @Borg and @Drakkith on this.

Thank you

Your courtesy is appreciated.

Scientists are not strangers to skepticism; however, the questions and speculations that you are posing appear, at least to me, to not pass basic criteria of reasonableness.

 

[russ_watters]

It was assumed I meant asteroid in this solar system, I did not, sorry, I should have been clearer. Asteroid in any solar system between us and the centre of the galaxy.

You should use simple geometry to calculate how big such an asteroid would need to be. Then you'll realize how impossible that idea is.

 

[Vanadium 50]

You should use simple geometry to calculate how big such an asteroid would need to be.

Further, if you had an asteroid that large, it would become a black hole.

 

[Monsterboy]

Messier 87 - Wikipedia -- someone updated that article very quickly. For the central black hole, M87*, the article quoted mass estimates like $(3.5 \pm 0.8) \times 10^9$ and $(6.6 \pm 0.4) \times 10^9$ solar masses, with a 2016 estimate of $7.22{}^{+0.34}_{-0.40} \times 10^9$ solar masses. The EHT consortium's estimate is $(6.5 \pm 0.2_{stat} \pm 0.7_{sys}) \times 10^9$ solar masses.

Those other mass estimates were made using the velocities of the stars and interstellar gas that surround the BH. They are well within the Newtonian limit, so the success of extrapolating toward the BH's event horizon is a success for GR, along with the approximately circular shape of the BH's shadow.

I read that there are actually two different results, one assumes that dark matter exits and other doesn't , assuming dark matter is real, calculations say it's mass is around 6.6 billion solar masses and without dark matter, calculations say it around 3.5 billion solar masses.

https://qr.ae/TWtsod