back to article Boffins discover tightest black hole binary system – and it's supermassive

Scientists have discovered the closest-ever supermassive black hole binary system. It's in the spiral galaxy NGC 7674, and the pair of voids are separated by a distance of less than one light year. Supermassive black hole binaries are rare. Until now, astronomers have only spotted one so far, about 24 light years apart. …

  1. Anonymous Coward
    Anonymous Coward

    LIGO events

    Three confirmed signals from these ripples have been detected by the Laser Interferometer Gravitational-wave Observatory since 2016

    As of today, LIGO has detected four events, not three. However, none of these events were from supermassive black hole pairs, which are by definition incredibly rare. These events all involve stellar-mass black holes.

    1. Rich 11 Silver badge

      Re: LIGO events

      Exactly. The paper explicitly states that LIGO isn't going to be able to detect this binary.

  2. Anonymous Coward
    Anonymous Coward

    Interesting ... This ever been a scene in some Sci-Fi...?

    "Single gigantic black holes gorging on surrounding matter are believed to exist in the centers of most large galaxies. Scientists believed that since galaxies collide and merge, the black holes might become entangled together to become a binary system. As they get closer and closer to one another, they cannot escape each other's gravity, and end up smashing into each other, sending gravitational waves rippling through spacetime."

  3. Anonymous Coward
    Anonymous Coward

    "As they get closer and closer to one another, they cannot escape each other's gravity, and end up smashing into each other, sending gravitational waves rippling through spacetime.'

    In classical physics the two masses would continue circling each other indefinitely, but Einstein showed that accelerating a mass creates those spacetime waves, which carry energy. Thus if two masses are bound in a mutual orbit they are considered be "accelerating" constantly (I think), and the resulting waves bleed off the system's angular momentum, transferring it to the universe as a whole.

    Normally such losses are minuscule even over billions of years, but not when many millions of solar masses are involved. Still, the waves are too weak to detect from this distance, altho they don't stay that way.

    As the holes draw closer they orbit faster too. That, and the tighter orbital radius, promotes bigger and better emission of gravity waves, speeding up the closing rate more and more. It's an exponential increase, so toward the end things happen fast. The frequency/power of the waves begins to rapidly go to the max (a lot), and then even a very weak force like gravity will make the universe sit up and take notice.

    During the last days, hours, or seconds before merger, colossal space warps are emitted at a furious rate. It may be these end-stage-merger waves that are being directly detected or maybe those from the actual merger, not sure.

    Don't ask me what happens at the merger, can't handle the math. ;-/

    1. Trigonoceps occipitalis

      "Don't ask me what happens at the merger ... "

      Easy, Cadbury's Cream Eggs are rubbish.

    2. This post has been deleted by its author

  4. John Smith 19 Gold badge

    I'd like to name them "Vic & Vince" Vega

    Because they are both very dark, and prone to causing extreme violence.

    It's a Black suit jacket.

    1. handleoclast

      Re: I'd like to name them "Vic & Vince" Vega

      Shirley, Donald Jr. and Eric. Because they're very dense.

      1. Roundabout

        Re: I'd like to name them "Vic & Vince" Vega

        Face forward, sit up straight, and try to pay attention. We are discussing the nature of binary black holes. Your political bent is totally irrelevant.

  5. Destroy All Monsters Silver badge

    the pair of voids

    Not particulary voids. One could call them "spacetime horizons"

    1. Anonymous Coward

      We could call them "Null and Void."

    2. GruntyMcPugh

      @Destroy All Monsters "Not particulary voids. One could call them "spacetime horizons""

      Indeed, a void is where no matter exists, but a black hole is super dense matter. Odd to use the word in this context therefore. The laws of physics could be said to void beyond that event horizon I guess.

      1. Paul Kinsler Silver badge

        The laws of physics could be said to void beyond that event horizon I guess

        The (known/accepted) laws of physics work just fine past the horizon, but don't work near the central singularity because it's (errr) too singular; and we don't know how to modify or replace those laws in such extreme situations.

        In fact, if you pick the right coordinates (i.e. Kruskal–Szekeres) you can see that nothing very interesting happens to the spacetime metric at the event horizon, even if the horizon looks somewhat remarkable from further away.

        1. GruntyMcPugh

          Re: The laws of physics could be said to void beyond that event horizon I guess

          I'll have to brush up, I was under the impression that the 'size' of a black hole, the Schwarzschild radius, was only relevant from the outside(ie, there's no 'normal' space inside the event horizon), and that once inside the event horizon, being stretched towards the singularity was inevitable, and time effectively stops?

      2. Anonymous Coward
        Anonymous Coward

        Blak hole density

        ... a black hole is super dense matter ...

        Interestingly enough, super-massive black holes do not have to be particularly dense. For example, the black hole at the centre of the Andromeda galaxy has a mass between 1.1e8 and 2.3e8 solar masses. It's average density is therefore somewhere between 1.5 g/cm3 (density of dry sand) and 0.3 g/cm^3 (density of flour).

        1. Cuddles Silver badge

          Re: Blak hole density

          "... a black hole is super dense matter ...

          Interestingly enough, super-massive black holes do not have to be particularly dense."

          Indeed. The more accurate way of putting would be "A black hole is super dense matter surrounded by some interesting gravitational effects". The singularity at the centre is extremely dense, but the black hole itself is usually taken to mean everything up to the event horizon, most of which is pretty much empty. It's similar to atoms really - a nucleus is extremely dense, but atoms are mostly empty space and aren't particularly dense overall.

          1. Paul Kinsler Silver badge

            Re: A black hole is super dense matter surrounded by some interesting gravitational effects

            I'd put it the other way around - a black hole is some interesting gravitational effects - notably an event horizon - usually generated by a large super-dense mass

      3. Anonymous Coward
        Anonymous Coward

        Can matter exist where there's no time?

        1. anadish
      4. Anonymous Coward

        In fact black holes are generally vacuum solutions, so in a sense they are not super-dense matter.

  6. Kaltern

    Or Zan and Dramas.

    1. John Mangan

      Or Zathras and Zathras?

    2. kyza


      Sympathy upvote.

      1. Kaltern

        Re: @Kaltern

        And 2 more... See, people do care!

        (apart from the miserable git who downvoted my other post. I imagine I'll get over the emotional trauma, eventually.

  7. eldakka Silver badge


    as it provides more evidence that supermassive black holes collide in galaxies, and are the a source of gravitational waves.


    1. Anonymous Coward
      Anonymous Coward

      Well, the ones we can detect, anyway.

  8. Banksy

    "Separated by a distance of less than one light-year"

    You could fit a space bus through there.

    1. LaeMing

      Re: "Separated by a distance of less than one light-year"

      That's how Han did the Kessel Run.

  9. TRT Silver badge
    Paris Hilton

    Tight black hole

    that sucks everything in? In fact two holes close together. See icon.

  10. Nick Ryan Silver badge

    Standard units of measure? (@Katyanna Quach)

    The supermassive black holes have a whopping combined mass of about forty million times the mass of the Sun.

    Sorry Katyanna Quach but the mass of the Sun is not a valid unit of measure on this site. Please report to the Vulture Central Standards Bureau for, erm, "training".

    1. Naselus

      Re: Standard units of measure? (@Katyanna Quach)

      Yes, she means '3.745318353333333*10^24 LINQ Hotel Recyclings'.

      Hopefully that'll clear up some confusion among the commentards.

  11. Kaltern

    I'm quite sad noone upvoted me for my clever Edding's reference :(

    1. LaeMing

      I'll be equally sad if anyone does up vote me for my stupid StarWars reference :-/

  12. Pirate Dave Silver badge

    24 light years apart

    still qualifies as a "binary"? Wow, didn't know that. Thought the scales for binaries were much smaller. Learned something today I did.

    1. Anonymous Coward
      Anonymous Coward

      Re: 24 light years apart

      We're talking about basically two dwarf galaxies' worth of mass, so a 24ly separation is barely comfortable.

    2. Naselus

      Re: 24 light years apart

      I believe they just have to be in a stable orbit around a mutual center of mass, so distance is only important in so far as it impacts their gravitational pull on each other. With objects as gravitationally massive as black holes, that means a binary system could form across a truly enormous distance - potentially including a system of smaller stars orbiting each.

      1. Anonymous Coward
        Anonymous Coward

        Re: 24 light years apart

        Those stars would have to be in tight orbits to avoid the gravitational churning of the binary system, which would either get them consumed or ejected fairly quickly. But I'd guess that tight orbit stars wouldn't last all that much longer, what with their own gravity wave losses and regular tugs from the other hole.

        Everything around and between the holes will be totally cleared out by now, except for a few of the stars in distant orbit around both holes that are perturbed gradually until they finally drop into the Grand Blender and get flung into eternity, either outward or inward.

  13. anadish

    It is quite probable, but it is impossible for any interferometer based GW receiver to sense such a GW wave from a future merger of these reported suspected black holes. It is impossible, even, if the interferometer is thousands of miles long. Primarily, because, gravity still travels at infinite speed as proposed by Newton; Einstein, indeed, could not change the speed. Let me add, 6 years earlier, minuscule gravitational waves of a wide frequency range (nearly zero to around 3 KHz) were first produced and detected in my lab late in 2010 and were reported in a US patent application which now is a US patent 8521029. You can find the patent detail on the USPTO site as well as on google patents . You can check out gravitational waves and my work on Wikipedia. Let me also add, even if I am letting out a little secret, it is impossible to register any black hole mergers otherwise too, primarily because of the sheer volume of mergers — I cannot talk more on this subject — besides due to too much of GW noise present around us (read in my patent about how this noise is generated). So, let me tell you, LIGO actually never detected any black hole mergers in the past too. The least I can say is that the reported mergers were a result of the intense imagination of the LIGO folks, to say the least. Unless LIGO is not confident of their so-called GW wave findings from BH mergers, why should they be tweeting this research with excitement? Then let us not forget it is a finding by a low-credibility Indian team and India has staked USD300 million for a disused LIGO setup to be shipped to India with a new name INDIGO.

  14. ntevanza


    What happens if one black hole judges its sovereignty impugned and votes to leave the binary system?

  15. Baldrickk

    If two supermassive black holes collide in a galaxy

    Does it make any noise*?

    *obviously not (vacuum), but would it produce any noticable effects that we could 'see' without LIGO?

    1. picturethis

      Re: If two supermassive black holes collide in a galaxy

      "Does it make any noise*?"

      Only if someone is there to detect it.

    2. anadish

      Re: If two supermassive black holes collide in a galaxy

      Rather with LIGO you can never see anything, as GW speed is actually infinite and an interferometer based GW detector can never work in such a situation. However, other kind of GW detectors like AURIGA can work in outer space but not on the earth due to a lot of GW noise generated by man made sources. Still, BH mergers are impossible to detect because of their sheer numbers in the universe all around. Only possibility is to detect a nearby neutron star merger which could be detectable because of its proximity and hence stronger GW.

    3. Anonymous Coward

      Re: If two supermassive black holes collide in a galaxy

      I'm not sure about supermassive BH collisions, but generally BH collisions are rather dark things: most of the interesting stuff is expected to come off as gravitational radiation.

      The reason for this is that BHs are only really visible in the EM spectrum if they have accretion disks -- disks of inspiraling matter. Accretion disks are not long-lived things: they need continual care and feeding, and in particular the BH needs to have some suitably nearby star that it can tear matter off to form the accretion disk: usually this is a companion star in a binary. But BH/BH binaries don't have such companion stars: the companion 'star' is another BH. So they generally don't have accretion disks at all, and so they are not very visible in the EM spectrum.

      I am not sure the extent to which this would go through for supermassive BH binaries though. I suspect that they generally would be quite dark in the EM spectrum as well, but I'm not sure.

  16. hoola Silver badge

    As another example of just how bonkers space can be, the Crab nebular has a Pulsar at its centre, rotating every 33ms. Just how something that big can rotate so quickly is just incredible.

    Of cause it could just be a little green being with a very powerful laser and a Raspberry Pi experimenting and having fun out in space.

    1. JCitizen

      I welcome..

      our little green Raspberry Pi wielding overlord!

    2. Anonymous Coward
      Anonymous Coward

      The crab pulsar is not that big

      I think it's about 20km in diameter. It's still impressive to think of something that big rotating that fast. There are pulsars which spin at many hundreds of Hz, which is even more terrifying.

  17. Palpy

    But is a BH superdense matter?

    Or is it a severely deformed and (almost) permanent kink in spacetime?

    My very limited layman's understanding is that the event horizon is just the boundary inside which nothing can either escape or avoid falling toward the singularity. Given that all matter inside the EH must fall eventually (OK, eventually in some frame of reference) to the singularity, it would seem possible for a quiescent BH to contain no matter at all, just a chaotically spasming quantum-scale spot where Einsteinian physics says gravity is infinite.

    Kip Thorne wrote a bit of scientific speculation (a decade or more ago, so probably dated) about what would befall an astronaut who entered a black hole. As I recall, the astronaut would experience extreme stretching, and chaotic tidal pushing and pulling, and then as she approached the singularity, her molecules and atoms would be torn apart.

    Thorne described the destruction of space and time itself at the singularity by using an analogy: time permeates the three dimensions of spacetime like water permeating wood. The singularity separates time from space like water is evaporated from wet wood in a fire, and then space itself is consumed.

    Caveat lector: I'm writing from memory, and may have got it wrong.

    And of course, as mentioned these so-called events all depend on what frame you use when you describe them. From an outside perspective, nothing falls past the EH anyway -- falling objects just get slower and redder and then appear to stop at the EH.

    Physicists, please correct as necessary.

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