Black hole wakes up and has a light snack

Apr 02, 2013

(Phys.org) —Astronomers have watched as a black hole woke up from a decades-long slumber to feed on a low-mass object – either a brown dwarf or a giant planet – that strayed too close. A similar feeding event, albeit on a gas cloud, will soon happen at the black hole at the centre of our own Milky Way Galaxy.

The discovery in galaxy NGC 4845, 47 million light-years away, was made by ESA's Integral , with follow-up observations from ESA's , 's and Japan's MAXI X-ray monitor on the .

Astronomers were using Integral to study a different galaxy when they noticed a bright X-ray flare coming from another location in the same wide field-of-view. Using XMM-Newton, the origin was confirmed as NGC 4845, a galaxy never before detected at high energies.

Along with Swift and MAXI, the emission was traced from its maximum in January 2011, when the galaxy brightened by a factor of a thousand, and then as it subsided over the course of the year.

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Astronomers using ESA’s Integral and XMM-Newton space telescopes, NASA’s Swift and the MAXI (Monitor of All-sky X-ray Image) instrument on the International Space Station have made the first detection of a substellar object being disrupted by a black hole. The discovery was made in the 47 million-light-year-distant galaxy, NGC 4845. substellar object moving through space and encountering the black hole, whereupon its outer layers are ripped away and spiral towards the black hole. The debris becomes heated and emits a blast of X-ray radiation before fading away once the material is consumed. The object lies in the mass range of 14–30 Jupiter masses, corresponding to either a brown dwarf or a large gas planet. Credit: ESA

"The observation was completely unexpected, from a galaxy that has been quiet for at least 20–30 years," says Marek Nikolajuk of the University of Bialystok, Poland, lead author of the paper in & Astrophysics.

By analysing the characteristics of the flare, the astronomers could determine that the emission came from a halo of material around the galaxy's central black hole as it tore apart and fed on an object of 14–30 Jupiter masses. This size range corresponds to brown dwarfs, substellar objects that are not massive enough to fuse hydrogen in their core and ignite as stars.

However, the authors note that it could have had an even lower mass, just a few times that of Jupiter, placing it in the range of gas-giant planets.

Recent studies have suggested that free-floating planetary-mass objects of this kind may occur in large numbers in , ejected from their parent solar systems by gravitational interactions.

The black hole in the centre of NGC 4845 is estimated to have a mass of around 300 000 times that of our own Sun. It also likes to play with its food: the way the emission brightened and decayed shows there was a delay of 2–3 months between the object being disrupted and the heating of the debris in the vicinity of the black hole.

"This is the first time where we have seen the disruption of a substellar object by a black hole," adds co-author Roland Walter of the Observatory of Geneva, Switzerland.

"We estimate that only its external layers were eaten by the black hole, amounting to about 10% of the object's total mass, and that a denser core has been left orbiting the black hole."

The flaring event in NGC 4845 can be seen as a warm-up act for a similar event expected in the supermassive black hole at the centre of our own , perhaps even this year.

While there are no brown dwarfs or planets on the menu this time, a compact cloud of gas amounting to just a few Earth masses has been seen spiralling towards the black hole and is predicted to meet its fate soon.

Along with the object seen being eaten by the black hole in NGC 4845, these events will tell astronomers more about what happens to the demise of different types of objects as they encounter of varying sizes.

"Estimates are that events like these may be detectable every few years in galaxies around us, and if we spot them, Integral, along with other high-energy space observatories, will be able to watch them play out just as it did with NGC 4845," says Christoph Winkler, ESA's Integral project scientist.

Explore further: How baryon acoustic oscillation reveals the expansion of the universe

More information: "Tidal disruption of a super-Jupiter in NGC 4845," by M. Nikolajuk and R. Walter is published in Astronomy & Astrophysics, April 2013.

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User comments : 26

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Jo Blas
1.8 / 5 (12) Apr 02, 2013
I don't understand why physorg often anthropomorphises stars, nebulae and black holes like this. You're a science site, for frak's sake. Why not just refer to 'tree spirits' as well?
cantdrive85
1 / 5 (7) Apr 02, 2013
Oh nooo, the scary black hole monster. Are they ever gonna leave Oprah alone.
Q-Star
4.3 / 5 (16) Apr 02, 2013
I don't understand why physorg often anthropomorphises stars, nebulae and black holes like this. You're a science site, for frak's sake. Why not just refer to 'tree spirits' as well?


If ya are referring to the title, then your critism is misplaced. The article, including the title, was taken verbatim from the European Space Agency.

Most of the articles, and their titles, that appear on this site are from sources outside of physorg. Physorg is a clearinghouse and compiler of news releases in the various fields of science, no more, no less.
GSwift7
5 / 5 (5) Apr 02, 2013
I like the term "disruption". Kinda makes it sound like a minor thing. I'd hate to be "disrupted" in this manner. lol.

On the serious side:

its external layers were eaten by the black hole, amounting to about 10% of the object's total mass, and that a denser core has been left orbiting the black hole


Nice support for our theory that the gas giant planets are composed of a solid core at the center. It's always comforting when observations match up with our assumptions.
jibbles
4.5 / 5 (8) Apr 02, 2013
I don't understand why physorg often anthropomorphises stars, nebulae and black holes like this. You're a science site, for frak's sake. Why not just refer to 'tree spirits' as well?


because it's a better read. because it's fun. because nobody will suddenly think that a black hole is actually a person.
yash17
1 / 5 (1) Apr 03, 2013
"This is the first time where we have seen the disruption of a substellar object by a black hole,"

Then, I expect we will get more observation like that kind in the future.
LarryD
1 / 5 (1) Apr 03, 2013
Okay, this is just one more case that makes about why a disk? If material from a 'passing' star is attracted by a BH why not over the spherical EH? Would it be because a BH might have an unstable spherical EH through some kind of redistribution of angular properties so that matter becomes attracted along a plane containing the highest tangent velocity. Thus later producing jets at the axis of roration and angular v/a vector?
Lurker2358
4 / 5 (2) Apr 03, 2013
Solid objects orbit in a plane, not a shell. Thus when the solid object (or a planet) is disrupted and some of it's matter escapes it will naturally form a planar shape as it falls to the greatest local center of gravity.

Frame dragging and conservation laws cause the spiraling effects.
GSwift7
5 / 5 (1) Apr 03, 2013
We assume that our own solar system was formed with more than the remaining 8 planets, and that some of the original planets were ejected and/or broken apart. If the above mechanism is typical of planetary break-up due to gravity, then where are the cores of the planets we lost here? The main asteroid belt is thought to be the remains of a protoplanet, and the remaining material looks like crust and mantal material. Where's the core material? Ejected or eaten by the sun I guess? I suspect that we will eventually find exoplanets around other stars that fit the profile of a core remnant from a failed planet, when our observatories become good enough to detect them.
rkolter
5 / 5 (1) Apr 03, 2013
its external layers were eaten by the black hole, amounting to about 10% of the object's total mass, and that a denser core has been left orbiting the black hole


Nice support for our theory that the gas giant planets are composed of a solid core at the center. It's always comforting when observations match up with our assumptions.


The fact that the data supports the possibility that the outer layers of a gas giant were peeled away does not mean that is what actually happened, nor does it mean that gas giants have a solid core.
GSwift7
5 / 5 (1) Apr 03, 2013
The fact that the data supports the possibility that the outer layers of a gas giant were peeled away does not mean that is what actually happened, nor does it mean that gas giants have a solid core


That's entirely true, but the two theories are mutually consistent, which makes each of them more likely to be generally correct. That's all I my comment means. To say that it verifies either of them as being correct, as you correctly point out, is taking it too far. I simply pointed out the connection between the two theories and that they are mutually consistent. They are both still based on inference rather than direct observation of a solid core. It's just math, but since the two were each reached by independent means, it lends some credibility to each.
LarryD
not rated yet Apr 03, 2013
Lurker2358, thank you, yes I am aware of 'natural' formation of disks but center of galaxies with SMBH are always spherical while the main spiral arms or disk appear to remain in a plane 'outside'the central sphere. Is there a w/site that would explain this for me?
GSwift7
5 / 5 (1) Apr 04, 2013
but center of galaxies with SMBH are always spherical while the main spiral arms or disk appear to remain in a plane 'outside'the central sphere. Is there a w/site that would explain this for me?


While the center of a spiral galaxy does bulge, it is not spherical. Objects in the bulge should not be in stable locations there, as the forces around them will tend to pull them in line with the plane of the disc. The reason discs form has to do with conservation of angular momentum and the fact that natural systems will follow the path of least resistance when shedding potential energy. (shedding potential energy is a natural law and is called entropy in thermodynamics). The reason a disc forms is because this is the most efficient way for the system to increase its entropy (think of entropy as decay, and everything in nature wants to decay).

This is about as simple as I can make it.

http://en.wikiped...ion_disc
LarryD
not rated yet Apr 04, 2013
Thank you GSwift7. Please note that although a layman I do have a technical b/g as I worked in QC labs most of my working life and also self taught just a little higher maths (eg. SR/GR, Spinors,QM...just the BASICS of course)so can appreciate what you write. But even the Wiki link you offer states '...yet unknown mechanism for angular momentum redistribution.....In other words, angular momentum should be transported outwards for matter to accrete.' Do we yet understand how this this is connected to or overcomes any centripetal forces which always act towards the center? Or is this overcome because of non-uniform motion?
Again, thanks
GSwift7
5 / 5 (1) Apr 05, 2013
yet unknown mechanism for angular momentum redistribution.....In other words, angular momentum should be transported outwards for matter to accrete.' Do we yet understand how this this is connected to or overcomes any centripetal forces which always act towards the center?


As I understand it, it's just the details we are missing. We don't have the ability to do the complex math which would be required to model this. It would be a many-body gravitational problem with essentially infinite number of bodies. We just can't compute that. I'm pretty sure that if we had a computer program sophisticated enough and a computer powerful enough, the mechanism could be calculated from basic principles. No matter what the details are, the basic laws of entropy and conservation of momentum must apply. The reason we see the disc shape repeated in so many places is because it is efficient, and the system is following the path of least resistance. That is a universal truth.
GSwift7
5 / 5 (1) Apr 05, 2013
Do we yet understand how this this is connected to or overcomes any centripetal forces which always act towards the center? Or is this overcome because of non-uniform motion?


From a human perspective, the stars and galaxies seem static, but they are dynamic and ever-changing and evolving over longer time scales than we normally deal with. The apparent structures such as discs and arms do change over time and objects in galaxies are ejected or fall into the central black hole with some regularity. So, in regard to your question, there isn't really a balance between inertia and gravitational forces. Eventually, everything will either be ejected or fall to the center. Stability is only an illusion caused by our short perception of time.

We have rough estimates for the forces and mechanisms, with upper and lower bounds based on observations. That range of values changes the details, but the gneral mechanisms remains the same.
Fleetfoot
5 / 5 (1) Apr 05, 2013
yet unknown mechanism for angular momentum redistribution.....In other words, angular momentum should be transported outwards for matter to accrete.' Do we yet understand how this this is connected to or overcomes any centripetal forces which always act towards the center?


As I understand it, it's just the details we are missing. We don't have the ability to do the complex math which would be required to model this.


This article gives an insight into the complexity. The basic answer is viscosity and turbulence but the devil is in the details:

http://phys.org/n...sks.html
cantdrive85
1 / 5 (4) Apr 05, 2013
This article gives an insight into the complexity. The basic answer is viscosity and turbulence but the devil is in the details:

http://phys.org/n...sks.html

The real devil in the details is determining the proper physics to be used, and in this case simple hydrodynamics of ideal gases falls pathetically short.
Fleetfoot
5 / 5 (4) Apr 05, 2013
This article gives an insight into the complexity. The basic answer is viscosity and turbulence but the devil is in the details:

http://phys.org/n...sks.html

The real devil in the details is determining the proper physics to be used, and in this case simple hydrodynamics of ideal gases falls pathetically short.


However, if you read the article before replying, you'll see that the article is about dealing with the internal magnetic and electrical current effects in addition to the basic gas effects. The trouble is that you claim to think plasma is important but you can't even recognise plasma physics when you see it, it is only your comprehension that "falls pathetically short".
GSwift7
5 / 5 (1) Apr 05, 2013
The real devil in the details is determining the proper physics to be used, and in this case simple hydrodynamics of ideal gases falls pathetically short


No, the basic laws do not fall short. Our ability to simultaneously calculate all of them at the same time for such a physically complex system is what falls short. We can approximate on large scales or we can do a fair job at very small scales, but we can't get the proper level of details at large scales. It's similar to modeling the atmosphere of the Earth. We can do broad strokes or little snapshots, but the middle ground is too complicated. When trying to apply details to large scales, the small differences between the min and max possible values for things like mass and pressure start to add up. Since you have a whole bunch of variable that can be adjusted, that problem goes exponentially huge. We're close, but small error bounds amplify just because of the number of them effecting each other.
LarryD
not rated yet Apr 05, 2013
Many thanks guys/gals. All great stuff as far as I'm concerned...next stop New VA radiation belt...???
Fleetfoot
5 / 5 (2) Apr 06, 2013
Many thanks guys/gals. All great stuff as far as I'm concerned...next stop New VA radiation belt...???


Next stop, with a bit of luck, a similar article about our own Sag A* when some of the gas cloud B2 falls into it later this year or early next:

http://www.univer...in-2013/
cantdrive85
1 / 5 (5) Apr 06, 2013
However, if you read the article before replying, you'll see that the article is about dealing with the internal magnetic and electrical current effects in addition to the basic gas effects. The trouble is that you claim to think plasma is important but you can't even recognise plasma physics when you see it, it is only your comprehension that "falls pathetically short".

I understand when the improper physics are applied, these a collisionless astrophysical plasmas that contain double layers, sheaths, and other complex phenomenon which are completely ignored in the article. This is another example of "plasma physicists" applying MHD where it's not applicable. As I said, the devil is using the PROPER physics to deduce the answers.
Fleetfoot
5 / 5 (2) Apr 06, 2013
I understand when the improper physics are applied, these a collisionless astrophysical plasmas that contain double layers, sheaths, and other complex phenomenon which are completely ignored in the article.


Since this is a dense dust medium where viscosity and momentum are the dominant factors, using the physics of a "collisionless" medium is completely inappropriate.

As I said, the devil is using the PROPER physics to deduce the answers.


Exactly, and you have just demonstrated that you have no idea how to work out what to apply.

In this case, the rule is simple, apply ALL the rules and let the computer tell you whether double layers etc. form or not. (That's why they have concerns that the modeling of the Hall effect isn't as good as they would like.)
cantdrive85
1 / 5 (2) Apr 06, 2013
The EM interactions of this plasma are the dominant factors, viscosity is a product of fluid dynamics, not plasma physics. Once again, knowing where to apply the physics. Unfortunately, for the theory, if the proper physics were applied the entire "standard" planet formation theory would collapse like the house of cards that it is. Without the pseudoscience of astrophysical plasma physics there is no possibility of nebular theory stellar and planetary formation. It's really quite easy for pseudoscience to infiltrate modern astrophysics, "magnetic reconnection" is the perfect example. As Alfven pointed out;
"A magnetic field line is by definition a line which is everywhere parallel to the magnetic field. If the current system changes, the shape of the magnetic field line changes but it is meaningless to speak about a translational movement of magnetic field lines." - Alfvén, op cit, p.12
Pseudoscience, meet science. Alfven had the advantage of experimentation, unlike the theoreticists.
Fleetfoot
not rated yet Apr 07, 2013
The EM interactions of this plasma are the dominant factors, viscosity is a product of fluid dynamics, not plasma physics. Once again, knowing where to apply the physics.


Correct, and since this is a dense medium where EM accelerations are cancelled rapidly by collisions, you have to include BOTH. Ignoring either one will give the wrong answer. The simulations include BOTH and show that in fact the dynamics has the greater influence but is significantly modified by the EM aspects.