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Black Holes May Fuel Antimatter Cloud

Those gamma rays coming out of galactic center, flagging the presence of an antimatter cloud of enormous extent, have spawned few explanations more exotic than the one we consider today: Black holes. Primordial black holes, in fact, produced in their trillions at the time of the Big Bang and left evaporating through so-called ‘Hawking radiation’ ever since. That’s the theory of Cosimo Bambi (Wayne State University) and colleagues, who are studying the same antimatter cloud we recently examined here in terms of its possible connection with low mass X-ray binary stars.

Hawking radiation offers a mechanism for small black holes to lose mass over time. But since the phenomenon has never been observed, the upcoming launch of the GLAST (Gamma-ray Large Area Space Telescope) satellite again looms large in significance. GLAST should be able to find evaporating black holes, assuming they are there, and there is even some possibility that the Pierre Auger Observatory may eventually detect tiny black holes created when high-energy cosmic rays slam into the upper atmosphere. If so, we would have a window into any evaporative effects associated with these enigmatic events.

But assuming that black holes do evaporate, the trick is to figure out how fast, and that rate depends upon mass, with more massive black holes producing fewer evaporated particles. What Bambi’s team argues is that a mass of about 1016 grams, roughly that of a fairly common asteroid, will produce the right amount of antimatter to explain the detections. Theoretically, the signature radiation from black holes of this particular size should be observable given the right equipment, but neither the GLAST mission or ESA’s INTEGRAL satellite seems well suited for that task (more on the latter problem in this New Scientist story).

All of which is interesting it itself, but the paper offers a bonus:

We have considered evaporating primordial BHs [black holes], as a possible source of positrons to generate the observed photon 511 keV line from the Galactic Bulge. The analysis of the accompanying continuous photon background produced, in particular, by the same evaporating BHs, allows to fix the mass of the evaporating BHs near 1016 g. It is interesting that the necessary amount of BHs could be of the same order of magnitude as the amount of dark matter in the Galactic Bulge. This opens a possibility that such primordial BHs may form all cosmological dark matter. The background MeV photons created by these primordial BHs can be registered in the near future, while the neutrino flux may be still beyond observation. The significance of this model would be difficult to overestimate, because these BHs would present a unique link connecting early universe and particle physics.

So there’s a theory for you: Primordial black holes as the explanation for dark matter itself. But bear in mind that along with the x-ray binaries so recently considered in relation to galactic antimatter, other explanations are still in play, including type Ia supernovae and a host of far more exotic possibilities outlined in the introduction to the paper. GLAST should help, but the suspicion grows that the antimatter cloud at galactic center may remain enigmatic for some time to come.

The paper is Bambi et al., “Primordial black holes and the observed Galactic 511 keV line,” available online.

Comments on this entry are closed.

  • ljk January 24, 2008, 14:50

    That is ironic, because a recent announcement at the
    211st AAS meeting says the increased mass needed to
    make a black hole may mean there are fewer of them
    than previously thought.

    See here:


    But perhaps since this seems to refer to black holes made
    well after the Big Bang, then ones made during it might be
    a whole other matter.

    Imagine countless black holes from the most ancient of times
    in and around every galaxy in the Universe. I am amazed that
    any “regular” matter is still here at all after 13.7 billion years.

  • Administrator January 24, 2008, 15:16

    Larry, I think you’re right re black holes subsequent to the Big Bang. The question that still resonates is how long primordial black holes could survive, if indeed any have. It will be interesting to watch reaction to this paper.

  • ljk January 24, 2008, 15:36

    NASA is preparing to launch a new space telescope named GLAST to study the most violent explosions in the history of our Universe.



  • Ron S January 24, 2008, 17:05

    Assuming wikipedia is correct (http://en.wikipedia.org/wiki/Primordial_black_hole) any primordial black hole of >10^12 kg would still exist. Less massive ones would have already evaporated, per Hawking. With a theory that straddles quantum mechanics and relativity, and an understandable dearth of empirical data, any experimental evidence would benefit fundamental physics.

    If dark matter is primordial black holes, there may be a problem. If I understand correctly the current mapping of dark matter seems to imply it is weakly interacting with ordinary stuff. Of course tiny black holes are effectively like dust of negligible dimension so perhaps it would indeed behave similarly to weakly-interacting particles.

  • Eric James January 25, 2008, 1:33

    In regards to Hawking radiation, I don’t see any consideration for the potential energy of the infalling particles in relation to the black hole. Wouldn’t this energy potential change the mass/energy deficit ratio?

  • David January 25, 2008, 5:48

    Interesting paper, but I am very surprised that there was no mention of the MACHO observations which established through microlensing that old white dwarfs could explain a good fraction (~tens of percent) of the drak matter in the galactic halo.

  • ljk January 25, 2008, 9:48

    Wouldn’t white dwarfs in the galactic halo be visible even
    to our current instruments?

    Maybe dark matter is not made of just one kind of thing.
    Maybe it’s white dwarfs in the halo and black holes much
    further out. Would that be possible, or does DM have to
    be one thing or the other?

    And how does any of this relate to where Dark Energy
    come from?

  • Adam January 25, 2008, 16:38

    Hi Larry

    White dwarfs are visible in the Halo and have already been ruled out as the Dark Matter – that result came in a few years ago.

  • James M. Essig January 26, 2008, 23:10

    Hi ljk and Adam;

    Perhaps there are blackholes made of one or more types of cold dark matter. I remember the “black holes have no hair concept” that was developed during the 20 Century in which the only parameters that define a blackhole relative to the outside of the blackhole are: its electrical charge from infalling precursor electric charge and aggregated net charge after its formation; its mass, and its spin or angular momentum including its axis of rotation. Perhaps with the potential future discovery of supersymmetric partners to the known bosons and fermions, we will find other parameters that define blackholes. One candidate that makes an obvious choice for consideration is the field associated with the supersymmetric fermionic and bosonic partners of the photon and the electrically charged particles of the leptons and the quarks or the photino, the sleptons, and the squarks: – in short, the supersymmetric counterparts to the electric field or to electrical charge.

    If there are other unforseen types of cold dark matter or deeper symmetries yet beside Fermi-Dirac matter/antimatter symmetry and mattergy supersymmetric mattergy, then blackholes might have even more hair than we could have theoretically/mathematically anticipated.

    Perhaps there are astoundingly huge blackholes not colocated with significant amounts of baryonic matter in the voids of visible matter in our universe that have a mass of perhaps trillions if not quadrillions of solar masses instead of the record holder of about 10 billion solar masses or the more commom few billion solar mass blackholes that appear to populate many galaxies and appear to be associated with QUAZARS.

    If such blackholes where of the rotating variety, perhaps very large space craft could safely pass through the rotating like toroidal singularity analogue within the center and be transported to other universes or cosmically remote locations within our universe in space and/or time. Even whole planets might be made to safely pass through. At the very least, the planet Earth could pass through the event horizon of one of these huge babies and not be torn apart by gravitational tidal forces because the gravitational flux density change with respect to linear distance elements near the event horizon would be many orders of magnitude smaller than that for a solar massed blackhole.

    If no such huge blackholes exist in our observable universe, perhaps they exist in other portions of our universe wherein chance extreme random density mattergy concentrations where not smoothed out by inflation because these early would be aggragated masses were so huge. Perhaps if such mattergy concentrations were smoothed out, there existed within, density pockets that quickly collapsed into quadrillion solar mass class blackholes during the period ranging from the first few years to the first few 100 million million years after the Big Bang. However, given enough time for humanity to ply the depths of the observable universe and regions currently beyond, perhaps one day we will find such and make use of them somehow.



  • ljk January 28, 2008, 12:03

    Transient Pulses from Exploding Primordial Black Holes as a Signature of an Extra Dimension

    Authors: Michael Kavic, John H. Simonetti, Sean E. Cutchin, Steven W. Ellingson, Cameron D. Patterson

    (Submitted on 25 Jan 2008 (v1), last revised 25 Jan 2008 (this version, v2))

    Abstract: An evaporating black hole in the presence of an extra spatial dimension would undergo an explosive phase of evaporation. We show that such an event, involving a primordial black hole, can produce a detectable electromagnetic pulse, signaling the existence of an extra dimension of size $L\sim10^{-18}-10^{-20}$ m. We derive a generic relationship between the Lorentz factor of a pulse-producing “fireball” and the TeV energy scale. For a toroidally compactified extra dimension, transient radio-pulse searches probe the electroweak energy scale ($\sim$0.1 TeV), enabling comparison with the Large Hadron Collider. The enormous challenges of detecting quantum gravitational effects, and exploring electroweak-scale physics, make this a particularly attractive possibility.

    Comments: 11 pages, 2 figures

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

    Report number: VPI-IPNAS-08-04

    Cite as: arXiv:0801.4023v2 [astro-ph]

    Submission history

    From: Michael Kavic [view email]

    [v1] Fri, 25 Jan 2008 20:51:32 GMT (210kb,D)

    [v2] Fri, 25 Jan 2008 21:02:02 GMT (210kb,D)


  • ljk January 28, 2008, 12:09

    Quantum Vacuum and a Matter – Antimatter Cosmology

    Authors: Frederick Rothwarf, Sisir Roy

    (Submitted on 12 Mar 2007 (v1), last revised 25 Jan 2008 (this version, v3))

    Abstract: A model of the universe as proposed by Allen Rothwarf based upon a degenerate Fermion fluid composed of polarizable particle-antiparticle pairs leads to a big bang model of the universe where the velocity of light varies inversely with the square root of cosmological time, t. This model is here extended to predict a decelerating expansion of the universe and to derive the Tully-Fisher law describing the flat rotation curves of spiral galaxies. The estimated critical acceleration parameter, aoR, is compared to the experimental, critical modified Newtonian Dynamics (MOND) cosmological acceleration constant, obtained by fitting a large number of rotation curves.

    The present estimated value is much closer to the experimental value than that obtained with the other models. This model for aR(t) allows the derivation of the time dependent radius of the universe as a function of red shift Other cosmological parameters such as the velocity of light, Hubble’s constant, the Tully-Fisher relation, and the index of refraction of the aether can also be expressed in terms of redshift. This is compared with the statistical fitting for Veron-Cetty data (2006) for quasar red shifts and good agreement is found. This model also determines the time and/or redshift dependence of certain electromagnetic parameters, i.e., the permittivity; the permeability ; and index of refraction of free space. These are found to be useful in various cosmological theories dealing with light passing through media in motion.

    Comments: 19 pages, 5 Figures

    Subjects: Astrophysics (astro-ph)

    Cite as: arXiv:astro-ph/0703280v3

    Submission history

    From: Sisir Roy [view email]

    [v1] Mon, 12 Mar 2007 19:25:28 GMT (516kb)

    [v2] Tue, 12 Jun 2007 17:32:11 GMT (512kb)

    [v3] Fri, 25 Jan 2008 12:49:09 GMT (458kb)


  • ljk March 7, 2008, 11:05

    Artificial black hole created in lab

    physicswolrd Mar. 6, 2008


    University of St Andrews physicists
    are the first to create an
    artificial black-hole system in
    which Hawking radiation could be
    detected. The experiment used the
    refractive index of a fiber optic as
    the analogy for a gravitational
    field of a real black…


  • ljk March 9, 2008, 23:35

    First observation of Hawking radiation?

    March 6th, 2008 | by KFC |


    In 1974, Stephen Hawking predicted that black holes would emit radiation.

    So-called Hawking radiation is produced when pairs of virtual particles pop into existence near the event horizon of a black hole (as they do all over the universe). Usually these pairs simply annihilate each other and disappear. But Hawking predicted that in some cases, one of the pair would sucked into hole while the other escaped. When that happened, the black hole would appear to emit radiation.

    Nobody has actually observed Hawking radiation because it is too weak to see with our current gear. But perhaps scientists have been looking in the wrong place.

    Iacopo Carusotto from the Universita di Trento in Italy and colleagues say they have spotted Hawking radiation in their lab on Earth.

    Here’s what they did: the team created a mathematical model of an experiment with a Bose Einstein Condensate. The condensate flows along a waveguide with a particular speed, v. This sets up a kind of sonic horizon: any sound wave with speed less than v travelling back along the condensate can never cross this horizon.

    Seems simple enough. But because BECs are no ordinary objects, it turns out that the physics of this situation is exactly analagous to what goes on at the event horizon of a black hole. So Hawking radiation could form at the horizon.

    And sure enough, in their simulation, Carusotto and co observed the emission of a particular kind of sound wave called Bogoliubov phonons from the horizon, just as Hawking predicted.

    Given that this is a numerical simualiton, the team’s claim that: “our observations can be considered as a first independent proof of the existence of Hawking radiation,” might be a little over-optimistic. But we get the idea.

    Anybody got a BEC machine that could do this for real?

    Ref: arxiv.org/abs/0803.0507: Numerical Observation of Hawking Radiation from Acoustic Black Holes in Atomic BECs

  • ljk March 10, 2008, 12:58

    Review: The Mystery of the Missing Antimatter

    If antimatter is the mirror image of matter, why is the universe
    dominated by matter? Jeff Foust reviews a book that takes readers on
    a journey through modern physics to try and answer that question.


  • ljk March 22, 2008, 23:53

    Mesons could offer new clue in antimatter mystery

    Differing decay rates may point to ‘new physics’


  • ljk March 28, 2008, 22:24

    Why There’s More Matter Than Antimatter in the Universe

    Written by Fraser Cain

    In the first few moments of the Universe, enormous amounts of both matter and antimatter were created, and then moments later combined and annihilated generating the energy that drove the expansion of the Universe. But for some reason, there was an infinitesimal amount more matter than antimatter. Everything that we see today was that tiny fraction of matter that remained.

    But why? Why was there more matter than antimatter right after the Big Bang? Researchers from the University of Melbourne think they might have an insight.

    Just to give you an idea of the scale of the mystery facing researchers, here’s Associate Professor Martin Sevior of the University of Melborne’s School of Physics:

    “Our universe is made up almost completely of matter. While we’re entirely used to this idea, this does not agree with our ideas of how mass and energy interact. According to these theories there should not be enough mass to enable the formation of stars and hence life.”

    Full article here:


  • ljk April 21, 2008, 16:04

    Gamma Rays from Centaurus A

    Authors: Nayantara Gupta

    (Submitted on 18 Apr 2008)

    Abstract: Centaurus A, the cosmic ray accelerator a few Mpc away from us is one of the nearest sources of extremely high energy cosmic rays. It would be interesting to see whether the gamma ray data currently available from Centaurus A in the GeV-TeV energy band can be explained with only proton proton interactions. We show that to be consistent with the gamma ray luminosity observed in the GeV-TeV energy range and the correlated extreme energy cosmic ray events observed by the Pierre Auger experiment, mechanisms of $\gamma$-ray production other than proton proton interactions are needed inside this radio-galaxy.

    Comments: 5 pages

    Subjects: Astrophysics (astro-ph)

    Cite as: arXiv:0804.3017v1 [astro-ph]

    Submission history

    From: Nayantara Gupta [view email]

    [v1] Fri, 18 Apr 2008 13:28:10 GMT (5kb)


  • ljk May 22, 2008, 8:02

    Transient Astrophysical Pulses and Quantum Gravity

    Authors: Michael Kavic, Djordje Minic, John Simonetti

    (Submitted on 19 May 2008)

    Abstract: Searches for transient astrophysical pulses could open an exciting new window into the fundamental physics of quantum gravity. In particular, an evaporating primordial black hole in the presence of an extra dimension can produce a detectable transient pulse.

    Observations of such a phenomenon can in principle explore the electroweak energy scale, indicating that astrophysical probes of quantum gravity can successfully complement the exciting new physics expected to be discovered in the near future at the Large Hadron Collider.

    Comments: 7 pages, This essay received an honorable mention in the Gravity Research Foundation Essay Competition, 2008

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

    Report number: VPI-IPNAS-08-11

    Cite as: arXiv:0805.2941v1 [gr-qc]

    Submission history

    From: Michael Kavic [view email]

    [v1] Mon, 19 May 2008 20:07:42 GMT (8kb)


  • ljk June 25, 2008, 9:34

    Black holes as antimatter factories

    Authors: Cosimo Bambi, Alexander D. Dolgov, Alexey A. Petrov

    (Submitted on 20 Jun 2008)

    Abstract: We consider accretion of matter onto a low mass black hole surrounded by ionized medium. We show that, because of higher mobility of protons than electrons, the black hole would acquire positive electric charge.

    If the black hole’s mass is about or below $10^{20}$ g, the electric field at the horizon can reach the critical value which leads to vacuum instability and electron–positron pair production by the Schwinger mechanism. Since the positrons are ejected by the emergent electric field, while electrons are back–captured, the black hole operates as an antimatter factory which effectively converts protons into positrons.

    Comments: 4 pages, no figure

    Subjects: Astrophysics (astro-ph); High Energy Physics – Phenomenology (hep-ph)

    Report number: WSU-HEP-0808

    Cite as: arXiv:0806.3440v1 [astro-ph]

    Submission history

    From: Cosimo Bambi [view email]

    [v1] Fri, 20 Jun 2008 18:53:46 GMT (7kb)


  • ljk January 9, 2009, 10:37

    Primordial black holes are again on the limelight

    Authors: Marco Roncadelli (INFN, Sezione di Pavia, Italy), Aldo Treves (Physics Department, Universita’ dell’Insubria, Italy), Roberto Turolla (Department of Physics, Universita’ di Padova, Italy)

    (Submitted on 8 Jan 2009)

    Abstract: We derive a strong upper bound on the amount of Primordial Black Holes (PBHs) that can still be present in the Universe. Gravitational capture of PBHs by the Milky Way stars and subsequent accretion would produce a dramatic depletion of Sun-like stars and especially of white dwarfs, unless the average cosmic density and mass of PBHs are severely constrained.

    Our finding also helps to discriminate among the various production mechanisms of PBHs. Moreover, we show that a star becomes overluminous before its disappearance into a PBH for a time span independent of its mass, thereby providing a characteristic observational signature of the considered scenario.

    We stress that our result allows for the existence of stellar-mass black holes in a mass range that is forbidden by standard stellar evolution.

    Comments: 7 pages, no figures, submitted to PRL

    Subjects: Astrophysics (astro-ph)

    Cite as: arXiv:0901.1093v1 [astro-ph]

    Submission history

    From: Roberto Turolla [view email]

    [v1] Thu, 8 Jan 2009 17:19:55 GMT (10kb)


  • ljk September 10, 2009, 12:52

    Rapid Merger of Binary Primordial Black Holes

    Authors: Kimitake Hayasaki (1 and 2), Keitaro Takahashi (1 and 3), Yuuiti Sendouda (1), Shigehiro Nagataki (1) ((1) Yukawa Institute for Theoretical Physics, Kyoto University, (2) Hokkaido University, (3) Nagoya University)

    (Submitted on 9 Sep 2009)

    Abstract: We propose a new scenario for the evolution of a binary of primordial black holes (PBHs). We consider the dynamical friction by ambient dark matter and gravitational interaction between a binary and a circumbinary disk, assuming PBHs do not constitute the bulk of dark matter.

    After the turnaround, a PBH binary loses the energy and angular momentum by the two processes, which are very effective for a typical configuration. Finally the binary coalesces due to the emission of gravitational waves in a time scale much shorter than the age of the universe.

    We estimate the density parameter of the resultant gravitational wave background. Astrophysical implication concerning supermassive black holes is also discussed.

    Comments: 5pages,no figure

    Subjects: Cosmology and Extragalactic Astrophysics (astro-ph.CO)

    Cite as: arXiv:0909.1738v1 [astro-ph.CO]

    Submission history

    From: Kimitake Hayasaki [view email]

    [v1] Wed, 9 Sep 2009 16:48:56 GMT (12kb)