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A Particle Accelerator at Galactic Center?

With all the press being given to the Large Hadron Collider under construction at CERN, it’s interesting to see that the black hole believed to exist at the Milky Way’s center — the object called Sagittarius A* — seems to be going it one better. The LHC will be able to accelerate protons to seven trillion electronvolts. But Sgr A* evidently slings nearby particles even more energetically, reaching the 100 trillion electrovolt level. Not bad for an object considered to be relatively inactive compared to black holes in other galaxies, and one explanation for the hugely energetic gamma rays streaming from that part of our galaxy.

Black hole accelerator at work

The study in question, reported in Astrophysical Journal Letters, sees the black hole as a cosmic particle accelerator, a region where powerful magnetic fields push particles to extraordinary energies. At play is the interstellar gas extending roughly ten light years from the black hole. Fuvio Melia (University of Arizona) calls Sgr A* “…one of the most energetic particle accelerators in the galaxy, but” — and here’s the mechanism involved — “it does this by proxy, by cajoling the magnetized plasma haplessly trapped within its clutches into slinging protons to unearthly speeds.”

Image: An illustration of the idea that the black hole at the center of the Milky Way is like an extremely powerful particle accelerator, revving up protons in the surrounding magnetic plasma and slinging them into lower-energy protons with such energy that high-energy gamma rays result from the collision. The yellow line depicts a high-energy proton flung into a lower-energy proton in the hydrogen gas cloud. The green arrow represents the high-energy gamma ray that results from the proton collision. (Credit: Sarah Ballantyne).

High-energy protons, having been accelerated by their brush with the supermassive object at galactic center, then collide with protons from low-energy hydrogen, creating pions that decay into gamma rays. So here’s an explanation for some of the universe’s most exotic objects. Melia again:

“Ironically, even though our galaxy’s central black hole does not itself abundantly eject hyper-relativistic plasma into the surrounding medium, this discovery may indirectly explain how the most powerful black holes in the universe, including quasars, produce their enormous jets extending over intergalactic proportions. The same particle slinging almost certainly occurs in all black-hole systems, though with much greater power earlier in the universe.”

The paper is Ballantyne et al., “A Possible Link between the Galactic Center HESS Source and Sagittarius A*,” in Astrophysical Journal Letters 657 (March 1 2007), L13-L16. A preprint is available.

Comments on this entry are closed.

  • Stephen March 1, 2007, 15:29

    So, clearly the LHC should be axed. It will only take 26,000 years at the speed of light, to get our detectors into the path of these 100 trillion electronvolt particles…

  • Inger Benedikte April 9, 2007, 21:53

    I am wondering who gave CERN permission to place this particle accelerator into OUR Earth, which will in turn create many black holes and potentially break up the EARTH’S core structure.
    This is something that is DEEP concern for me and many other people.

    Why cant these physicists do this in space. WHO OWNS the CORE of the EARTH where they are placing their accelerator?

    I do not think these people have the right to do this to our Earth.
    Is there any way we can stop this from happening??

    Perhaps this is what is supposed to occur for the end of the Earth ot happen. Who knows.

  • Eric James April 10, 2007, 0:23

    Start a movement.

  • Adam April 10, 2007, 5:07

    Hi Inger

    The Large Hadron Collider isn’t very deep, just a few metres, but the Earth’s core is over 5150 kilometres down. Also the Collider isn’t pointed at the core, but at a big detector or else the physicists would see nothing.

    As for black holes – if any are made, and there’s some doubt they will be, they will decay away into other particles within microseconds. The predicted micro black holes are highly unstable, much like other particles, and disappear very quickly.

    The LHC weighs many, many thousands of tons and is much too big to build anywhere in space we can reach.

    People worry about many strange things, but the LHC should be the least of people’s concerns. Global warming and global terrorism are more immediate dangers for all of us. Our Earth is continually bombarded from space by very high energy particles called Cosmic rays which are made naturally by the Sun and by Galaxies in deep space. Such cosmic rays collide with our atmosphere, just like LHC particles will collide, but with much more energy. The collisions bathe us all in naturally made radiation, but we have evolved to survive it. For as long as Earth has existed the collisions have been occurring and they haven’t made any black holes big enough to threaten the Earth, so it’s very unlikely the LHC will affect the Earth at all. In fact it might teach us new ways of making energy so we can do something about Global Warming – and take money away from Global Terrorism.

  • MirrorStephen April 10, 2007, 9:41

    Inger, I strongly suggest that you start digging to the
    earth’s core and set up a guard post there so nobody,
    especially those pesky CERN scientists and their naughty
    particuler machines, can mess with our planet’s core!

    And be sure to stay there until they show up, okay?

  • ljk June 8, 2007, 9:44

    LHC to skip low-energy test runs (Jun 6)


    The Large Hadron Collider will not be ready in time to perform a
    low-energy “engineering run”, which was originally scheduled to take
    place this November, according to an official at CERN. This will leave
    the operators no chance to gain experience with the particle
    accelerator’s steering and detection systems before the high-energy runs
    begin in spring next year. The delay is due primarily to the failure of
    a Fermilab-built magnet during high-pressure tests in March.

  • ljk June 11, 2007, 16:52

    Professor proposes theory of unparticle physics

    Physorg.com June 11, 2007


    Howard Georgi, a physicist at
    Harvard University, has recently
    published a paper on “unparticle
    physics,” which suggests the
    existence of “unparticle stuff” that
    cannot be accounted for by the
    standard model. Unparticles can fit
    in a theory that has the property of
    continuous scale-invariance. A
    fractal is an example of discrete…


  • ljk June 26, 2007, 15:13

    Radio Synchrotron Emission from Secondary Leptons in the Vicinity of Sgr A*

    Authors: Roland M. Crocker, David Jones, David R. Ballantyne, Fulvio Melia

    (Submitted on 23 Jun 2007)

    Abstract: A point-like source of ~TeV gamma-rays has recently been seen towards the Galactic center by HESS and other air Cerenkov telescopes. In recent work (Ballantyne et al. 2007), we demonstrated that these gamma-rays can be attributed to high-energy protons that (i) are accelerated close to the event horizon of the central black hole, Sgr A*, (ii) diffuse out to ~pc scales, and (iii) finally interact to produce gamma-rays. The same hadronic collision processes will necessarily lead to the creation of electrons and positrons. Here we calculate the synchrotron emissivity of these secondary leptons in the same magnetic field configuration through which the initiating protons have been propagated in our model. We compare this emission with the observed ~GHz radio spectrum of the inner few pc region which we have assembled from archival data and new measurements we have made with the Australia Telescope Compact Array. We find that our model predicts secondary synchrotron emission with a steep slope consistent with the observations but with an overall normalization that is too large by a factor of ~ 2. If we further constrain our theoretical gamma-ray curve to obey the implicit EGRET upper limit on emission from this region we predict radio emission that is consistent with observations, i.e., the hadronic model of gamma ray emission can, simultaneously and without fine-tuning, also explain essentially all the diffuse radio emission detected from the inner few pc of the Galaxy.

    Comments: 11 pages, 2 figures. Accepted for publication in Astrophysical Journal Letters

    Subjects: Astrophysics (astro-ph)

    Cite as: arXiv:0706.3429v1 [astro-ph]

    Submission history

    From: Roland M. Crocker [view email]

    [v1] Sat, 23 Jun 2007 05:57:29 GMT (181kb)


  • Walter L. Wagner September 14, 2007, 1:32

    The Large Hadron Collider [LHC] at CERN might create numerous different particles that heretofore have only been theorized. Numerous peer-reviewed science articles have been published on each of these, and if you google on the term “LHC” and then the particular particle, you will find hundreds of such articles, including:

    1) Higgs boson

    2) Magnetic Monopole

    3) Strangelet

    4) Miniature Black Hole [aka nano black hole]

    In 1987 I first theorized that colliders might create miniature black holes, and expressed those concerns to a few individuals. However, Hawking’s formula showed that such a miniature black hole, with a mass of under 10,000,000 a.m.u., would “evaporate” in about 1 E-23 seconds, and thus would not move from its point of creation to the walls of the vacuum chamber [taking about 1 E-11 seconds travelling at 0.9999c] in time to cannibalize matter and grow larger.

    In 1999, I was uncertain whether Hawking radiation would work as he proposed. If not, and if a mini black hole were created, it could potentially be disastrous. I wrote a Letter to the Editor to Scientific American [July, 1999] about that issue, and they had Frank Wilczek, who later received a Nobel Prize for his work on quarks, write a response. In the response, Frank wrote that it was not a credible scenario to believe that minature black holes could be created.

    Well, since then, numerous theorists have asserted to the contrary. Google on “LHC Black Hole” for a plethora of articles on how the LHC might create miniature black holes, which those theorists believe will be harmless because of their faith in Hawking’s theory of evaporation via quantum tunneling.

    The idea that rare ultra-high-energy cosmic rays striking the moon [or other astronomical body] create natural miniature black holes — and therefore it is safe to do so in the laboratory — ignores one very fundamental difference.

    In nature, if they are created, they are travelling at about 0.9999c relative to the planet that was struck, and would for example zip through the moon in about 0.1 seconds, very neutrino-like because of their ultra-tiny Schwartzschild radius, and high speed. They would likely not interact at all, or if they did, glom on to perhaps a quark or two, barely decreasing their transit momentum.

    At the LHC, however, any such novel particle created would be relatively ‘at rest’, and be captured by Earth’s gravitational field, and would repeatedly orbit through Earth, if stable and not prone to decay. If such miniature black holes don’t rapidly evaporate and are produced in copious abundance [1/second by some theories], there is a much greater probability that they will interact and grow larger, compared to what occurs in nature.

    There are a host of other problems with the “cosmic ray argument” posited by those who believe it is safe to create miniature black holes. This continuous oversight of obvious flaws in reasoning certaily should give one pause to consider what other oversights might be present in the theories they seek to test.

    I am not without some experience in science.

    In 1975 I discovered the tracks of a novel particle on a balloon-borne cosmic ray detector. “Evidence for Detection of a Moving Magnetic Monopole”, Price et al., Physical Review Letters, August 25, 1975, Volume 35, Number 8. A magnetic monopole was first theorized in 1931 by Paul A.M. Dirac, Proceedings of the Royal Society (London), Series A 133, 60 (1931), and again in Physics Review 74, 817 (1948). While some pundits claimed that the tracks represented a doubly-fragmenting normal nucleus, the data was so far removed from that possibility that it would have been only a one-in-one-billion chance, compared to a novel particle of unknown type. The data fit perfectly with a Dirac monopole.

    While I would very much love to see whether we can create a magnetic monopole in a collider, ethically I cannot currently support such because of the risks involved.

    For more information, go to: http://www.LHCdefense.org


    Walter L. Wagner (Dr.)

  • ljk January 24, 2008, 10:34

    ESA’s orbiting gamma-ray observatory, Integral, has made the
    first unambiguous discovery of highly energetic X-rays coming
    from a galaxy cluster. The find has shown the cluster to be a
    giant particle accelerator.

    More at:


  • ljk April 15, 2008, 9:50

    Milky Way’s giant black hole awoke from slumber 300 years ago

    A team of Japanese astronomers using ESA’s XMM-Newton, along
    with NASA and Japanese X-ray satellites, has discovered that our
    galaxy’s central black hole let loose a powerful flare three centuries

    More at:


  • James M. Essig April 30, 2008, 0:23

    Hi Folks;

    An accelerator the diameter of the solar system would be huge. I can imagine a linac the length of the radius of the observable universe that would accelerate a proton for billions of years wherein the proton would gain about 100 GeV per kilometer. After having traveled 10 EXP 23 kilometers or 10 billion light years, it would have a kinetic energy of 10 EXP 25 GeV or 6 orders of magnitude greater than the Planck Energy. Obviously, the thermal radiation within the tube would have to be reduced to as close to zero K as possible, far cooler than the CMBR radiation, and the walls of the accelerator tube made superconducting to filter out as much virtual zero point fluctuations as possible which could interfere with the accelleration process. Thus, the tube in which the proton travels should have a microscopic diameter as small as possible.

    A longer tube yet just means greater gamma factors for the particle. I wonder what sort of physics we could discover at such high energies wherein the proton would have become a greatly relativistically contracted black hole along its axis of travel.

    Could you imagine a supercollider with the diameter of the Milky Way Galaxy or even with the diameter of the Observable universe? Talk about cosmic engineering projects! I wonder what we could discover with such machines.

    However, I’ll be happy to start with the LHC when it comes on line in May.



  • James M. Essig May 9, 2008, 15:48

    Hi Folks;

    I read in my new sub-atomic physics textbook copyrighted 2007 that a 1 to 2 TeV linac has been proposed which could accelerate electrons to 1 to 2 TeV. This would give an added window in terms of particle interactions within the TeV range to look for additional forces and elementary particle substructure as well as an added window of experimental opportunity to perhaps looks for additional Higgs Bosons, super symmetric particles and the like. It would be really cool if electronic substructures were found. This device would be a neat addition to the LHC in terms of the set of tools we would then have to study fundamental particle physics.



  • george scaglione May 10, 2008, 9:07

    jim, you know as i’ve said before.the new physics which may emerge from the LHC will certainly be a great thing for the space program in many ways! means of propulsion may be suggested that we do not now as of yet drem of! thank you very much! george

  • george scaglione May 12, 2008, 9:32

    hello all,lol i just read the above article upon which this discussion is based.how is that possible you may ask!? well i generally read the excerps of things people have said that you get when you sign on to the site and then look into the ones that catch my attention most.big mistake! from now on i will check more fully so as to not miss anything! boy oh boy are those comments interesting in that article! the study of space will without doubt yield incredible information for us to study.and (lol) THAT collider we didn’t even have to build!!!!! but DO NOT get me wrong i am still waiting on the edge of my seat for the LHC to go online.the very best to all,your friend george

  • James M. Essig May 27, 2008, 17:04

    Hi George;

    As I was up thinking late last evening, it occurred to me that an accelerator that would accelerate mildly charged carbon buckyballs or other carbon fullerines might produce beams with exceptional effective luminosity related to the number of collision events per beamed particle packet or bundle. For useful efficiency, a colliding beam type of accelerator would be best for such particles wherein two beams of fullerines having equal and opposite momentum would collide head on in a manner typical for colliding accelerators.

    Because carbon buckyballs and other fullerines have such high chemical bonding energies, they should not be adversely effected by the electro-dynamic accelerator fields so long as an adequate vacuum can be maintained within the accelerator tubes so as to prevent collisions of the fullerine molecules with other gas particles.

    Other charged particle candidates could include precisely sized nano-scale diamond dust particles and nano-scale and perhaps even micron scale Uranium, Plutonium, Hafnium, Bismuth, Gold, Lead, Thorium, Americium and the like elements in their various isotopes. Such beams, if and when they prove feasible as accelerator particle beams would greatly increase the number of collision events in colliding beam experiments.

    Other massive particles might be utilized in super conducting super colliders such as any charged forms of quarkonium such as strangelets and the like.

    For these heavier particles, I can imagine that steering magnets of extraordinary strength would be required to steer and focus the accelerated particles.


    Your Friend Jim

  • ljk August 17, 2009, 13:27

    Interstellar magnetic fields in the Galactic center region

    Authors: Katia Ferriere

    (Submitted on 14 Aug 2009)

    Abstract: We seek to obtain a picture of the interstellar magnetic field in the Galactic center region that is as clear and complete as possible.

    To that end, we review the observational knowledge that has built up over the past 25 years on interstellar magnetic fields within ~ 200 pc of the Galactic center. We then critically discuss the various theoretical interpretations and scenarios proposed to explain the existing observations. We also study the possible connections with the general Galactic magnetic field and describe the observational situation in external galaxies.

    We propose a coherent picture of the magnetic field near the Galactic center, which reconciles some of the seemingly divergent views and which best accounts for the vast body of observations.

    Our main conclusions are the following. In the diffuse intercloud medium, the large-scale magnetic field is approximately poloidal and its value is generally close to equipartition with cosmic rays (~ 10 microG), except in localized filaments where the field strength can reach ~ 1 mG. In dense interstellar clouds, the magnetic field is approximately horizontal and its value is typically ~ 1 mG.

    Comments: 16 pages, 2 figures

    Subjects: Galaxy Astrophysics (astro-ph.GA)

    Cite as: arXiv:0908.2037v1 [astro-ph.GA]

    Submission history

    From: Katia Ferriere [view email]

    [v1] Fri, 14 Aug 2009 11:22:43 GMT (181kb)


  • ljk September 9, 2009, 13:04

    Kerr Black Holes as Particle Accelerators to Arbitrarily High Energy

    Authors: Máximo Bañados, Joseph Silk, Stephen M. West

    (Submitted on 1 Sep 2009)

    Abstract: We show that intermediate mass black holes conjectured to be the early precursors of supermassive black holes and surrounded by relic cold dark matter density spikes can act as particle accelerators with collisions, in principle, at arbitrarily high centre of mass energies in the case of Kerr black holes.

    While the ejecta from such interactions will be highly redshifted, we may anticipate the possibility of a unique probe of Planck-scale physics.

    Comments: 4 pages, PDFLaTex, 3 figures, accepted for publication in Phys.Rev.Lett

    Subjects: High Energy Physics – Phenomenology (hep-ph); Cosmology and Extragalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics – Theory (hep-th)

    Cite as: arXiv:0909.0169v1 [hep-ph]

    Submission history

    From: Stephen West [view email]

    [v1] Tue, 1 Sep 2009 12:43:22 GMT (531kb,D)