Black hole that doesn't emit x-rays discovered near massive star

Jan 16, 2014 by Bob Yirka report
Trailed intensity image of the two lines constructed from the phase binned spectra. Two orbital cycles are displayed for clarity. The colour scale indicates counts normalized to the continuum, with the black colour corresponding to 0.98 and the white colour to 1.08 in Fe II and 1.16 in HeII. Credit: Nature 505, 378–381 (16 January 2014) doi:10.1038/nature12916

(Phys.org) —Researchers in Spain have discovered a black hole that doesn't reveal itself through x-ray radiation thrown off by material that is being sucked into it. In their paper published in the journal Nature, team members from several research institutions throughout Spain, report that the black hole appears to exist as a companion (binary) to a massive Be star that spins so fast it's surrounded by a gas disk.

Up until now, virtually all have been discovered via x-ray radiation signals—as material is pulled in past the point of no return, radiation is flung out into space where it is noted by space scientists here on Earth. In this new effort, the research team was able to identify the black hole because of its behavior, rather than its signature.

Many Be have been found to have companions—most of the time they are (neutron stars) but never before has a Be star been found to have a black hole as a companion. The star, named MWC 656 is really big—approximately 10 to 16 times as massive as our sun. It spins really fast too (approximately 671,000 mph) which the researchers say, explains why the black hole next to it doesn't emit any radiation. They suggest that because the star is spinning so fast, it casts gas into a disk surrounding its equator which in turn is cast off towards the black hole, but rather than being pulled in, the gas joins an that surrounds the "mouth" of the black hole, moving so fast (due to the angular momentum of the gas cast off from the star) that it can't be pulled in. Thus the disk simply continues to grow larger.

The black hole is pretty big too (approximately 3.8 to 6.9 more massive than our sun) which likely puts it in the category of stellar mass black holes—those that come into existence when a star runs out of fuel.

This video is not supported by your browser at this time.
Animation of the system MWC 656. The Be star spins at extremely high speed, ejecting matter through an equatorial disc. Part of this matter falls on to the black hole forming an accretion disc. Animation: Gabriel Pérez - SMM (IAC). On the photo, UB researchers, Marc Ribó and Josep M. Paredes, who have participated in the research.

The discovery of the "silent" black hole suggests that many more like it might exist, which will undoubtedly lead researchers to look for more, now that they know what to look for.

Explore further: Taking the pulse of a supermassive black hole

More information: A Be-type star with a black-hole companion, Nature 505, 378–381 (16 January 2014) DOI: 10.1038/nature12916

Abstract
Stellar-mass black holes have all been discovered through X-ray emission, which arises from the accretion of gas from their binary companions (this gas is either stripped from low-mass stars or supplied as winds from massive ones). Binary evolution models also predict the existence of black holes accreting from the equatorial envelope of rapidly spinning Be-type stars (stars of the Be type are hot blue irregular variables showing characteristic spectral emission lines of hydrogen). Of the approximately 80 Be X-ray binaries known in the Galaxy, however, only pulsating neutron stars have been found as companions. A black hole was formally allowed as a solution for the companion to the Be star MWC 656 ( also known as HD 215227), although that conclusion was based on a single radial velocity curve of the Be star, a mistaken spectral classification6 and rough estimates of the inclination angle. Here we report observations of an accretion disk line mirroring the orbit of MWC 656. This, together with an improved radial velocity curve of the Be star through fitting sharp Fe II profiles from the equatorial disk, and a refined Be classification (to that of a B1.5–B2 III star), indicates that a black hole of 3.8 to 6.9 solar masses orbits MWC 656, the candidate counterpart of the γ-ray source AGL J2241+4454 (refs 5, 6). The black hole is X-ray quiescent and fed by a radiatively inefficient accretion flow giving a luminosity less than 1.6 × 10−7 times the Eddington luminosity. This implies that Be binaries with black-hole companions are difficult to detect in conventional X-ray surveys.

Press release

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antialias_physorg
4.3 / 5 (6) Jan 16, 2014
the gas joins an accretion disk that surrounds the "mouth" of the black hole, moving so fast (due to the angular momentum of the gas cast off from the star) that it can't be pulled in.


Does this mean that eventually the accretion disc around the black hole will become so massive that there will be a (relatively) short time in which large parts of it will fall in (due to turbulence/gravitational contraction of a part of it)

or...which may be more weird...will it coalesce into a fast rotating planet around the black hole? Now that would be one weird place to stand on (and one great place to have a science probe at)
shavera
5 / 5 (3) Jan 16, 2014
I'd rather have an image or sketch of this disk dynamic than the words. I can't exactly picture what they're trying to claim is happening.

aa_p: I think it may be that it's just a temporary (in cosmological terms) phenomenon, maybe further perturbations would cause the kind of emissions we're used to, but... I dunno. Like I said, hard to picture what they're describing.
Whydening Gyre
5 / 5 (1) Jan 16, 2014

Does this mean that eventually the accretion disc around the black hole will become so massive that there will be a (relatively) short time in which large parts of it will fall in (due to turbulence/gravitational contraction of a part of it)


We'd prob'ly see some x-rays THEN....

or...which may be more weird...will it coalesce into a fast rotating planet around the black hole? Now that would be one weird place to stand on (and one great place to have a science probe at)

Like a Dyson sphere - but different...
antialias_physorg
5 / 5 (3) Jan 16, 2014
We'd prob'ly see some x-rays THEN....

Possibly one of the sources for the GRBs we have been witnessing elsewhere

Like a Dyson sphere - but different...

Can't really see it forming a Dyson swarm. It'd just clump into a regular/singular planet mostly made up of hydrogen.
(Dyson spheres aren't stable in any case, as the forces are very different between equator and poles. Most matter would concentrate at the equator, but you'd need most stability at the poles)

Depending on how close the accretion disc is to the star planet formation may not be possible due to the gravity gradient. But that only comes into play VERY close to the black hole.
Widdekind
not rated yet Jan 16, 2014
perhaps the radiation from the BH is beamed (in some direction away from earth) ?
Widdekind
5 / 5 (1) Jan 16, 2014
www.nature.com/na...6-f3.jpg

FIGURE 3
--------------
Filled circles indicate radial velocities of the Be star, as obtained from the Fe II 4,583 Å line; open circles indicate those of the companion star, extracted from the He II 4,686 Å line

Be = 10-16 Msol
BH = 4-7 Msol

Orbital radius of BH >> Be
BH orbits BEYOND outer edge of Be disk
Be disk seems centered on the two stars' mutual center-of-mass (explaining the constant FeII line)...
within disk, the Be star revolves around (explaining the oscillating HeII line)...
BEYOND the disk, the BH revolves around, out were there is no longer any gas to consume, and so is completely quiescent
adam_russell_9615
4 / 5 (2) Jan 16, 2014
How do they know its a black hole? Did I misread the article or is that part missing? I know they said "by its behavior" but thats not an answer.
Returners
5 / 5 (4) Jan 16, 2014
How do they know its a black hole? Did I misread the article or is that part missing? I know they said "by its behavior" but thats not an answer.


They can calculate it's mass based on the behavior of the other star, and since it's not emitting radiation, they infer that it must be a BH and not a neutron star.
Mimath224
4.5 / 5 (2) Jan 16, 2014
@adam_russell_9615 as I read the artical the BH is inferred or an indication that it is a black hole. As 2 other posts point out x-rays may provide a 'confirmation' later.
A star with that size and that period of rotation would also be oblate and I wonder if fututre tidal forces would first increase the the content of accretion and finally have some devastating affect on the star?
cantdrive85
2.3 / 5 (3) Jan 17, 2014
How do they know its a black hole? Did I misread the article or is that part missing? I know they said "by its behavior" but thats not an answer.

That is how every BH is "discovered". A BH has never been seen, only inferred.
Widdekind
4.5 / 5 (2) Jan 17, 2014
the "BH" = 4-7 Msol >> TOV limit for NS (~3 Msol)

the disk must be annular, or else why is there an emission gap at the "0" velocity ? Seemingly, the disk material is all either moving (at least a little) towards, or else away -- no material is simply "suspended" in space. The disk is an annulus, with no material in the center; the Be star revolving around through the disk, like a fly on a record; the BH orbits beyond the annulus; which must also be inclined to the LOS, or else why is there no obvious BH occultation of disk / star light ? Perhaps the horizontal "bars" where the FeII gap closes, perhaps 30degrees or so above the bottom / middle Be star transits, are due to some sort of (re-)lensing of light ???
rockwolf1000
3.9 / 5 (7) Jan 17, 2014
How do they know its a black hole? Did I misread the article or is that part missing? I know they said "by its behavior" but thats not an answer.

That is how every BH is "discovered". A BH has never been seen, only inferred.


The physical properties of a BH prevent it from ever being "seen". Thus it's existence must be inferred.
Whydening Gyre
4.3 / 5 (3) Jan 17, 2014
How do they know its a black hole? Did I misread the article or is that part missing? I know they said "by its behavior" but thats not an answer.

That is how every BH is "discovered". A BH has never been seen, only inferred.


The physical properties of a BH prevent it from ever being "seen". Thus it's existence must be inferred.

Like the Higgs "particle"... inferred but not seen.
rockwolf1000
3 / 5 (5) Jan 17, 2014
How do they know its a black hole? Did I misread the article or is that part missing? I know they said "by its behavior" but thats not an answer.

That is how every BH is "discovered". A BH has never been seen, only inferred.


The physical properties of a BH prevent it from ever being "seen". Thus it's existence must be inferred.

Like the Higgs "particle"... inferred but not seen.

Precisely.
cantdrive85
1 / 5 (5) Jan 17, 2014
How do they know its a black hole? Did I misread the article or is that part missing? I know they said "by its behavior" but thats not an answer.

That is how every BH is "discovered". A BH has never been seen, only inferred.


The physical properties of a BH prevent it from ever being "seen". Thus it's existence must be inferred.

Like the Higgs "particle"... inferred but not seen.

And this doesn't bother anyone? A phenomena that by construct cannot ever be observed or falsified. That's metaphysics, not science.
Captain Stumpy
5 / 5 (4) Jan 17, 2014
And this doesn't bother anyone? A phenomena that by construct cannot ever be observed or falsified. That's metaphysics, not science.

@cantdrive85
idk about that- prove there is air
and lets make this fun... do it with only what you have in your bathroom
Whydening Gyre
5 / 5 (1) Jan 17, 2014
@cantdrive85
idk about that- prove there is air
and lets make this fun... do it with only what you have in your bathroom

That was actually pretty funny, Cap'n...:-)
Whydening Gyre
5 / 5 (1) Jan 17, 2014
Y'all DO realize that this is just a "real life" training exercise for an AI, don't ya?
IMP-9
5 / 5 (4) Jan 18, 2014
And this doesn't bother anyone? A phenomena that by construct cannot ever be observed or falsified. That's metaphysics, not science.


No, as usual you misrepresent the situation. You can observe it and falsify it, for example measure the innermost stable orbits or by showing that the shadow is not observed or lots of other things. We can't directly observe lots of things, magnetic field for an example, however we can measure their effects and they can be falsified.
Returners
4 / 5 (1) Jan 18, 2014
@cantdrive85
idk about that- prove there is air
and lets make this fun... do it with only what you have in your bathroom


Take one empty mouthwash bottle. Put the lid half-way on it and squeeze it, then put the lid on all the way, and as tight as you can.

Viola, the bottle holds it's new shape because there is less air inside of it than it's natural volume, and the outside pressure is therefore greater than the inside pressure.

Nevertheless, proving that "something" unknown is happening is quite a different animal than proving precisely what that "something" is or must be.
Captain Stumpy
4.5 / 5 (2) Jan 18, 2014
@Returners
Take one empty mouthwash bottle....

LOL ya missed the point.

He cannot see/etc air, and can only see movement in air when something is small enough to be taken by the current while still remaining visible (like water or dust)
IOW- indirect measurement.
He can only infer that air exists because of observations of the effects of air/things in the air, not a direct measurement.

See IMP-9's comment above yours
Returners
3 / 5 (1) Jan 18, 2014
No, as usual you misrepresent the situation. You can observe it and falsify it, for example measure the innermost stable orbits or by showing that the shadow is not observed or lots of other things. We can't directly observe lots of things, magnetic field for an example, however we can measure their effects and they can be falsified.


Indirect observations can only offer pieces to theory. Interpretations of most indirect observations are just that: interpretations.

Dark Matter Problem:

After a certain distance from the core of galaxies, the stars all start to orbit at the same speed, regardless of distance.

Hypothesis:

It's because of invisible matter which almost never interacts with ordinary matter.

Another hypothesis:

It's because of a missing variable or term in the gravity equation.

Another hypothesis:

An invisible, non-interacting epicycle exists for each star which holds them in place.

Another hypothesis

Mond

Hypothesis:

Time Warp misleads about orbital speed
Returners
3 / 5 (2) Jan 18, 2014
Discovering 3 particles per year which pass through the Earth doesn't necessarily even mean they are "Dark Matter". If you can't "see" them then how do you prove they are what you think they are?

They could be "Dark Photons" or "Dark Neutrinos" or a Tachyon for all you know.

So you could easily infer that something, potentially an unknown particle, hit the argon atom, but excluding other unknown unknowns not identical to the unknown you're looking for is even harder than finding that unknown in the first place, when they are (all) invisible and non-interacting.
Captain Stumpy
5 / 5 (2) Jan 18, 2014
Hypothesis:

Another hypothesis:

@Returners
"...anyone can string together words to create the most outlandish of hypotheses. But where is the substance. In the face of an overwhelming body of observational and theoretical evidence that describes all of these phenomena in tremendous (and successful) detail [meaning the standard model- CS], why should anyone pay attention to this ...[new hypothesis]?"
T. Thompson, refuting the electric universe hypothesis Sun, 3 May 1998

fits well with the above, dont you think?
For a hypothesis to become a theory, in which we are discussing above, it must pass a rigorous testing phase. When it makes it to theory (Standard model, BB, etc) it is because it makes predictions that can be measured/observed. Models/hypothesis that do not fit observations and make wrong predictions are discarded.

Science isnt about accepting something that sounds cool... that is faith
Whydening Gyre
5 / 5 (3) Jan 19, 2014
can only infer that air exists because of observations of the effects of air/things in the air, not a direct measurement.

Actually... EVERYTHING is inferred." I think therefore I am" is even an inference, if ya wanna take it to the bone...

vlaaing peerd
5 / 5 (2) Jan 20, 2014
I finally start to get Cantdrive...if I walk blindfolded into a lamp post, feels like it and has all the unmistakable traits of a lamp post I'm inferring it's existence. But if I see it, it is not inferred.

So something simple like music can therefore not be detected, only audibly inferred. That does make a lot of stuff in this universe metaphysical mumbojumbo.

I wonder how mr Cantdrive would interpret a picture of a lamp post though.
adam_russell_9615
not rated yet Jan 20, 2014
How do they know its a black hole? Did I misread the article or is that part missing? I know they said "by its behavior" but thats not an answer.


They can calculate it's mass based on the behavior of the other star, and since it's not emitting radiation, they infer that it must be a BH and not a neutron star.


I thought the odd part was that it was a black hole that was not emitting radiation. So then how could the fact that it is not emitting radiation show that it IS a black hole?
GSwift7
5 / 5 (2) Jan 22, 2014
Viola, the bottle holds it's new shape because there is less air inside of it than it's natural volume, and the outside pressure is therefore greater than the inside pressure


If you didn't know better, could you exclude the possibility that the cause of this is actually the aether. Surely you aren't proposing that millions of tiny, invisible particles fill the mouthwash bottle. That sounds awefully far-fetched.

I wonder how mr Cantdrive would interpret a picture of a lamp post though


It is in fact not a lamp post. That shape is the exact shape made by giant space lightning bolts. The picture you claim to be a lamp post is clear evidence of electrical discharge machining, the same mechanism that created the grand canyon of course. If you understood plasma, this would be obvious to you, however, nobody except Halton Arp and Hannes Alfven understand plasma. It's a conspiracy, and it's not fair.
GSwift7
5 / 5 (2) Jan 22, 2014
I thought the odd part was that it was a black hole that was not emitting radiation. So then how could the fact that it is not emitting radiation show that it IS a black hole?


The orbit of the star shows that there is a massive object orbiting with the star. We can calculate the mass of that object based on the motion of the star. An object that massive would be visible if it were any kind of 'normal' object. It's not possible to have a cold, dark object that massive. Even a neutron star which formed at the dawn of the Universe would not have had time to completely cool yet, and this is too massive to be a planet.

So, it's just a matter of eliminating all other 'known' choices. We don't really 'know' what a black hole is, but whatever is orbiting with that star exactly fits our definition of objects we call black holes.
Modernmystic
not rated yet Jan 22, 2014
Even the term black hole isn't well conceptulaized.

Do you mean the volume of the event horizon?
Do you mean what passes for space time on the other side of the horizon?
Do you mean the singularity itself?
Do you mean all of the above?
....
GSwift7
5 / 5 (1) Jan 22, 2014
Do you mean the volume of the event horizon?
Do you mean what passes for space time on the other side of the horizon?
Do you mean the singularity itself?
Do you mean all of the above?


In this case, those questions are irrelevant. They have calculated the location of a center of gravity and its mass. Since there's no visible object of sufficient mass at that location, there's no known option other than a black hole. Said black hole will have all the properties you mentioned (event horizon, singularity, etc.). None of the questions you mention really matter at this point, since they aren't talking about anything other than its effect on the companion star.

Intersting questions though - The volume of the EH, for example is a complicated subject. I'm not sure what formula you would use, since it's not a Euclidian space inside.
Modernmystic
5 / 5 (1) Jan 22, 2014
The volume of the EH, for example is a complicated subject. I'm not sure what formula you would use, since it's not a Euclidian space inside.


Indeed. However it does manifest itself in a Euclidean universe (we did decide it's flat didn't we?). I'm sure there has been some math done on the interface between the EH and "normal" space, but I don't know what it might say or if it gives meaningful answers yet. Inside the EH I think all bets are off...well maybe not ALL bets. I don't think there are unicorns galloping on rainbows inside for instance ;)
GSwift7
5 / 5 (1) Jan 22, 2014
don't know what it might say or if it gives meaningful answers yet. Inside the EH I think all bets are off...well maybe not ALL bets. I don't think there are unicorns galloping on rainbows inside for instance ;)


That gave me a good belly chuckle.

My intuition tells me that the volume calculation would be done like a field calculation, as an integral of all the volumes from the EH to the center, so it's probably infinity, whatever that's supposed to mean. That would indicate that things falling in may never acually reach the center. Or, depending on how you work the terms, I suppose it could mean they 'instantaneously pop' to the center? Depends on how you set up the frame of reference. Whether it's from an outside observer, from the pov of the infalling object, or the pov of the unicorn standing at the center, would make a world of difference.

Personally, I think only the local reference frame makes sense.
Whydening Gyre
5 / 5 (1) Jan 22, 2014
My intuition tells me that the volume calculation would be done like a field calculation, as an integral of all the volumes from the EH to the center, so it's probably infinity, whatever that's supposed to mean. That would indicate that things falling in may never acually reach the center. Or, depending on how you work the terms, I suppose it could mean they 'instantaneously pop' to the center? Depends on how you set up the frame of reference. Whether it's from an outside observer, from the pov of the infalling object, or the pov of the unicorn standing at the center, would make a world of difference.

Personally, I think only the local reference frame makes sense.

(Gasp), g-Swift! Does that mean - the Unicorn did it!?!?
GSwift7
5 / 5 (1) Jan 22, 2014
(Gasp), g-Swift! Does that mean - the Unicorn did it!?!?


In the library with the candle stick I think.