back to article Mystery black hole hides by curbing its appetite

A well-known radio source has turned out not to be the galaxy it's been classified as for 20 years, but a surprisingly quiet black hole. The discovery is causing a bit of buzz among astrophysicists because it suggests there could be thousands or millions more “covert” black holes out there waiting to be discovered. It took …

  1. Anonymous Coward
    Anonymous Coward

    "Having the black hole turn up in a survey of a small patch of sky implies that there should be many others in the Milky Way alone – thousands of times as many as previously estimated."

    Not really, unless one is turning up in lots of surveys of a small patch of sky.

    1. Anonymous Coward
      Anonymous Coward

      Yes. The "one data point" problem. While they can use mass distribution and star observations to estimate how many black holes there are, I'm not sure they can for how many "unseen" black holes there are.

    2. Doctor Syntax Silver badge

      If this is the first such survey and it turns up one then the probability that it's a one-off seems small.

      The immediate thought is could this account for the missing mass? Given that it's a small black hall you'd need a lot of them.

      1. Anonymous Coward
        Anonymous Coward

        I would assume no, as some scientists/mathematicians/astrophysicist etc have tried to accound for dark matter via naked black holes. Dark matter usually outstrips most assumptions, and as it seems to lie outside of galaxies, black holes don't seem to fit the bill.

        That is, unless totally naked (no matter around them or gas), then we would see a faint glow around some galaxies as little jets of gas/stars/wondering rocks hit the black holes. We see none, hence it is "dark" matter, not "warmed and glowing with a snug jumper" matter. :)

        http://www.forbes.com/sites/startswithabang/2016/05/26/black-holes-as-dark-matter-heres-why-the-idea-falls-apart/#3a4646246d7b

        However the above article suggests some early black holes could account for some of the matter. The closer we get with each slice, the closer to knowing what is left that is truly "dark", but still existing (no, not magic, just invisible like radio waves or sub atomic particles :P ).

  2. Andy 68

    The only way to really check....

    Get the Asp Explorer out of storage and go and look for yourself

  3. cortland

    Absconder

    Another possibility is that this black hole is receding from us fast enough to shift x-ray frequencies into the RF spectrum. That's a very unlikely possibility, but if so, it would be a tantalizing observation.

    1. Alan Brown Silver badge

      Re: Absconder

      "That's a very unlikely possibility"

      Indeed: That kind of recession would show up pretty damned quickly inside a galaxy. There's simply too much "stuff" around for a black hole to be able to zip through stealthily at a large fraction of the speed of light (it'd need to be 80%+ to get that kind of redshift)

      1. Destroy All Monsters Silver badge

        Re: Absconder

        The black hole is detected based on interaction with its low-mass companion... which evidently doesn't zip around with serious fraction of lightspeed.

        So no.

        1. cortland

          Re: Absconder

          Well, darn! And here the local PD was ready to ask for warrants!

          New headline: Informant grasses Black Hole

    2. Anonymous Coward
      Anonymous Coward

      Re: Absconder

      "Another possibility is that this black hole is receding from us fast enough to shift x-ray frequencies into the RF spectrum."

      Not if it's in our own galaxy it wouldn't be

  4. Prst. V.Jeltz Silver badge
    Alien

    isnt it obvious?

    well obviously its an artificially created blackhole , probably to draw matter from the nearby star before it goes supernova and destroys the planets the residents are living on.

    ie A cooling system

    possibly they use it for rubbish disposal too.

    1. Wingtech

      Re: isnt it obvious?

      "possibly they use it for rubbish disposal too."

      Maybe the debris from the construction of a hyperspace express route through a nearby star system.

      1. Anonymous Coward
        Anonymous Coward

        Re: isnt it obvious?

        "a cooling system"

        Orbited by large containers of Stellar Artois?

  5. Little Mouse Silver badge

    The real reason they're good at hiding...

    ...is that the colour of a black hole is black. And the colour of space, your average space colour, is...

    You know the rest.

    1. Prst. V.Jeltz Silver badge

      Re: The real reason they're good at hiding...

      Swirly thing alert!

      1. Destroy All Monsters Silver badge

        Re: The real reason they're good at hiding...

        You just need to find the areas where ominous music can be heard to be playing...

  6. Ugotta B. Kiddingme

    missing mass (or at least some portion thereof) found?

    Disclaimer: I most certainly do NOT lay claim to knowledge or credentials to make the text below a statement. I am trying to expand my own learning and therefore continue presenting it as questions.

    "could be thousands or millions more 'covert' black holes out there waiting to be discovered."

    I've asked this for several years: How do we know there aren't many more black holes that we simply can't see for one reason or another and THEY are, at least in part, the so-called "missing mass" of the universe? There may well be many black holes from the early universe that have since consumed everything around them (therefore not emitting x-ray death screams) and with not much behind them (from our perspective, therefore not giving away their position with gravitational lensing/distortion). I readily grant that it would take an AWFUL LOT of these to make up the required total mass to fit the models but, it would certainly lessen the need to rely on exotic theories. And this may also help to explain the uneven distribution of matter in the universe. Perhaps in some of the particularly empty regions sit one or more black holes that have digested everything within reach and sit quietly and darkly waiting for something else to eat.

    1. Brewster's Angle Grinder Silver badge

      Re: missing mass (or at least some portion thereof) found?

      The LIGO results have made us take that idea a lot more seriously. But the type of system described here is almost certainly a normal astrophysical system, because it's paired with an ordinary star and because the black hole is too light to be primordial. (We have observational evidence that primordial black holes can't be "light" -- IIRC, under 20-30 solar masses.)

      1. Destroy All Monsters Silver badge

        Re: missing mass (or at least some portion thereof) found?

        There is a problem as there are ongoing search for microlensing effects due to black holes passing in front of other stars, and I have not heard that a massive population of hitherto invisible black holes is now suspected to exist.

        1. Dagg

          Re: missing mass (or at least some portion thereof) found?

          Just because we can't find it doesn't mean it doesn't exist.

          One option is to do the maths to see if this type of phenomena could explain dark matter / dark energy...

          1. Brewster's Angle Grinder Silver badge

            Re: missing mass (or at least some portion thereof) found?

            Here's one example of someone doing some maths. It says a black hole population of 20-100 solar masses isnt ruled out by observation evidence.

  7. Brewster's Angle Grinder Silver badge

    How come this article didn't once mentioned the phrase Roche lobe overflow. It's even in the paper. Come on, my entire existence is devoted to hearing the words Roche lobe overflow.

    1. Francis Boyle

      Roche lobe overflow

      They were good in the seventies but these days they're just treading water. Or am I thinking of another band.

  8. E 2

    Dark matter, indeed.

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