Chandra Captures Enticing Evidence Of Black Hole’s Bondi Radius

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Those who are interested in black holes are familiar with the event horizon, but the Chandra X-Ray Observatory is giving us an even more detailed look into the structure surrounding these enigmas by imaging the inflowing hot gases. Galaxy NGC 3115 contains a supermassive black hole at its heart and for the first time astronomers have evidence of a critical threshold known as the “Bondi radius”.

Located approximately 32 million light years from the Solar System in the constellation of Sextans, NGC 3115 is a prime candidate for study. Contained in its nucleus is a billion-solar-mass black hole which is stripping away hot gases from nearby stars which can be imaged in X-ray. “The Chandra data are shown in blue and the optical data from the VLT are colored gold. The point sources in the X-ray image are mostly binary stars containing gas that is being pulled from a star to a stellar-mass black hole or a neutron star. The inset features the central portion of the Chandra image, with the black hole located in the middle.” says the team. “No point source is seen at the position of the black hole, but instead a plateau of X-ray emission coming from both hot gas and the combined X-ray emission from unresolved binary stars is found.”

In order to see the machination of the black hole at work, the Chandra team eradicated the signal given off by the binary stars, separating it from the super-heated gas flow. By observing the gas at varying distances the team could then pinpoint a threshold where the gas first becomes impacted by the supermassive black hole’s gravity and begins moving towards the center. This point is known as the Bondi radius.

“As gas flows toward a black hole it becomes squeezed, making it hotter and brighter, a signature now confirmed by the X-ray observations. The researchers found the rise in gas temperature begins at about 700 light years from the black hole, giving the location of the Bondi radius.” says the Chandra team. “This suggests that the black hole in the center of NGC 3115 has a mass of about two billion times that of the Sun, supporting previous results from optical observations. This would make NGC 3115 the nearest billion-solar-mass black hole to Earth.”

Original Story Source: Chandra News Further Reading: Resolving the Bondi Accretion Flow toward the Supermassive Black Hole of NGC 3115 with Chandra.

17 Replies to “Chandra Captures Enticing Evidence Of Black Hole’s Bondi Radius”

  1. Yo Tammy, minor nitpick at the second paragraph, first line…

    When referring to the Solar System, it should be preceded by the definite article “the”, not the pronoun “our”, as there is only one Solar System – external planetary systems are called stellar system(s), or solar system(s) (lower case).

    1. hi, ivan… pick on me all you like. 😀

      as writers, we’ve just received word to follow the Chicago Manual of Style for capitalization proceedures. this means when referring to anything within – and inclusive – of our Solar System that it needs to be capitalized… such as Sun, Moon, etc. when it’s elsewhere, it gets lower case.

      but i’ll agree that it needs “the” and not “our” to be correct!

  2. @ALL,

    This article reminds me of a question put to me by a friend some time ago. Since that time my friend has returned to following the wild geese and spouting some version of science elsewhere. I quote that friend here, although I really do not understand what is meant by the question. My friend is not a native english speaker and does not feel any need to communicate other than to use a pidgin of his language with his limited command of American English spoken with a British-Texas accent and drawl.

    “The way any stellar system remains in gravitic balance over time is if the distributed mass sources support each other with their perturbations through a variety of yielding systems. This generalization, of course, can be made more specific if the major factors (mass, distance, force) of each element can be known and those factors ‘congeal’ so to speak.”
    (I did paraphrase my memory in this preamble.)

    With this as the basis from which to formulate a question my friend asks, “What is the nature of effects on ‘masses in equilibrium’ presently understood to occur when SMBHs weakly interacting with distant mass sources previously interacting to a smaller part, now, as they too are ‘stripped and swallowed’, and the mass center moves away from the sphere of influence on the original system of ‘masses in equilibrium'”.

    I think what is being questioned is this; does a mass which is being influenced by another mass, en-cascading to another etc. ‘feel’ less of this multi-mass interaction as a BH begins to strip mass from the farthermost influences since the force of gravity diminishes over distance. The BH event horizon, not-withstanding, is not any part of the factors here, as that cubic is well down the scale of influences being discussed. I don’t know that this is what is meant but it does seem to be somewhat similar from what I can tell.

    Mary

    1. That sounds like an analog description to how vortexes feed new ones down the size scales until they dissipate on small scales. Which indeed makes for poetry:

      “Big whorls have little whorls
      That feed on their velocity;
      And little whorls have lesser whorls
      And so on to viscosity.”

      [Lewis F. Richardson]

      However in this case it is wrong. The only requirement I know of for contracting gravitational mass (gas) clouds is their thermodynamical dissipation, this time in the form of heat radiation. Hence “balance” is consequence of the well known virial theorem. This is how Zwicky predicted the existence of dark matter.

      As for what happens gravitationally as mass reconfigures around a black hole, a test particle in a potential only feels the central charge so wouldn’t notice anything when far away. And the question of near SMBH mass behavior is what entertain many researchers, AFAIU.

      I.e. it is an open question. It would depend on the mechanisms, and no one has of yet proposed a “cascading” one what I know of. But I know very little of this.

    2. That sounds like an analog description to how vortexes feed new ones down the size scales until they dissipate on small scales. Which indeed makes for poetry:

      “Big whorls have little whorls
      That feed on their velocity;
      And little whorls have lesser whorls
      And so on to viscosity.”

      [Lewis F. Richardson]

      However in this case it is wrong. The only requirement I know of for contracting gravitational mass (gas) clouds is their thermodynamical dissipation, this time in the form of heat radiation. Hence “balance” is consequence of the well known virial theorem. This is how Zwicky predicted the existence of dark matter.

      As for what happens gravitationally as mass reconfigures around a black hole, a test particle in a potential only feels the central charge so wouldn’t notice anything when far away. And the question of near SMBH mass behavior is what entertain many researchers, AFAIU.

      I.e. it is an open question. It would depend on the mechanisms, and no one has of yet proposed a “cascading” one what I know of. But I know very little of this.

  3. If some space “body” is 32 million light years away, how do we know it is still there? Maybe if we could get out there it would be entirely different than what we see now.

    1. @valoispg,

      Of course at that time it was still there, this light [Xrays actually just a part of the EM radiation spectrum] is coming from that source as stated. Traveling to that source as you state, while impossible at present (never dash hope), would reveal the current structure(s) of this active galaxy nucleus (AGN or SMBH super massive black hole). The difference twixt then and the ‘impossible now picture’ is really moot. You may wish to engage a moot class on the ramifications embodied in your posit. We are talking about time duration of a very high order of magnitude.

      I’ll leave you with this set of thoughts.

      If your hand casts a shadow but the light source is extinguished, does the shadow still exist?

      Does the wall upon which the shadow is cast contain the shadow?

      Does the light source express the shadow of the hand or just negativity reveal it?

      Does the hand wish for light so much it robs the wall?

      Mary

      1. Right… But those questions doesn’t seem to illuminate the physics, as per your earlier rather correct description. I call “foul”! 😀

        never dash hope

        Make that reasonable hope, and you have a deal!

        [If you want to entertain unreasonable hope, it would be reasonable to do so in private.]

        Unless there is something very, very wrong with current understanding of physics, it is impossible to travel there during our species lifetime.

        That doesn’t come from a “no go” theorem as of yet, but from bits and pieces. However, bits and pieces can be made a solid wall as well as one large theorem!

  4. If some space “body” is 32 million light years away, how do we know it is still there? Maybe if we could get out there it would be entirely different than what we see now.

  5. The Bondi radius is the radius at which a black hole in a medium perturbs the matter. Matter with a density ? crosses a sphere with area 4?R^2 at a speed v so the amount of material entering that sphere is

    dM/dt = 4?R^2 ?v.

    The velocity and radius are dependent according to Newtonian gravity

    v^2 = 2GM/R, — > R = 2GM/v^2 from energy

    and we have

    dM/dt = 16?G^2M^2 ?/v^3

    or according to the radius

    dM/dt = 4sqrt{2}? sqrt{GM} ?R^{3/2}

    You can numerically solve this differential equation. The actual radius can be computed as the velocity at which material moves with the rest of matter with velocity u. Then for V = v + u we input R = 2GM/u.

    It is impressive that this 2 billion solar mass black hole has a Bondi radius of 700 light years. The point of this observation is that it demonstrates the existence of this thunderous black hole.

    LC

      1. @squidgeny,

        Neutron stars are the other compact object(s) to which this apply’s. The key here being compact. At some point in time in the future there might be some other use for the tensors described here, presently there is none.

        Mary

      2. Every gravitating body has a Bondi radius. This has some bearing on the issue with planets and their ability to clear the space around their orbit.

        LC

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