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World-wide Campaign Sheds New Light on Nature’s “LHC”

Recent observations of blazar jets require researchers to look deeper into whether current theories about jet formation and motion require refinement. This simulation, courtesy of Jonathan McKinney (KIPAC), shows a black hole pulling in nearby matter (yellow) and spraying energy back out into the universe in a jet (blue and red) that is held together by magnetic field lines (green).


In a manner somewhat like the formation of an alliance to defeat Darth Vader’s Death Star, more than a decade ago astronomers formed the Whole Earth Blazar Telescope consortium to understand Nature’s Death Ray Gun (a.k.a. blazars). And contrary to its at-death’s-door sounding name, the GASP has proved crucial to unraveling the secrets of how Nature’s “LHC” works.

“As the universe’s biggest accelerators, blazar jets are important to understand,” said Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) Research Fellow Masaaki Hayashida, corresponding author on the recent paper presenting the new results with KIPAC Astrophysicist Greg Madejski. “But how they are produced and how they are structured is not well understood. We’re still looking to understand the basics.”

Blazars dominate the gamma-ray sky, discrete spots on the dark backdrop of the universe. As nearby matter falls into the supermassive black hole at the center of a blazar, “feeding” the black hole, it sprays some of this energy back out into the universe as a jet of particles.

Researchers had previously theorized that such jets are held together by strong magnetic field tendrils, while the jet’s light is created by particles spiraling around these wisp-thin magnetic field “lines”.

Yet, until now, the details have been relatively poorly understood. The recent study upsets the prevailing understanding of the jet’s structure, revealing new insight into these mysterious yet mighty beasts.

“This work is a significant step toward understanding the physics of these jets,” said KIPAC Director Roger Blandford. “It’s this type of observation that is going to make it possible for us to figure out their anatomy.”

Over a full year of observations, the researchers focused on one particular blazar jet, 3C279, located in the constellation Virgo, monitoring it in many different wavebands: gamma-ray, X-ray, optical, infrared and radio. Blazars flicker continuously, and researchers expected continual changes in all wavebands. Midway through the year, however, researchers observed a spectacular change in the jet’s optical and gamma-ray emission: a 20-day-long flare in gamma rays was accompanied by a dramatic change in the jet’s optical light.

Although most optical light is unpolarized – consisting of light with an equal mix of all polarizations – the extreme bending of energetic particles around a magnetic field line can polarize light. During the 20-day gamma-ray flare, optical light from the jet changed its polarization. This temporal connection between changes in the gamma-ray light and changes in the optical polarization suggests that light in both wavebands is created in the same part of the jet; during those 20 days, something in the local environment changed to cause both the optical and gamma-ray light to vary.

“We have a fairly good idea of where in the jet optical light is created; now that we know the gamma rays and optical light are created in the same place, we can for the first time determine where the gamma rays come from,” said Hayashida.

This knowledge has far-reaching implications about how a supermassive black hole produces polar jets. The great majority of energy released in a jet escapes in the form of gamma rays, and researchers previously thought that all of this energy must be released near the black hole, close to where the matter flowing into the black hole gives up its energy in the first place. Yet the new results suggest that – like optical light – the gamma rays are emitted relatively far from the black hole. This, Hayashida and Madejski said, in turn suggests that the magnetic field lines must somehow help the energy travel far from the black hole before it is released in the form of gamma rays.

“What we found was very different from what we were expecting,” said Madejski. “The data suggest that gamma rays are produced not one or two light days from the black hole [as was expected] but closer to one light year. That’s surprising.”

In addition to revealing where in the jet light is produced, the gradual change of the optical light’s polarization also reveals something unexpected about the overall shape of the jet: the jet appears to curve as it travels away from the black hole.

“At one point during a gamma-ray flare, the polarization rotated about 180 degrees as the intensity of the light changed,” said Hayashida. “This suggests that the whole jet curves.”

This new understanding of the inner workings and construction of a blazar jet requires a new working model of the jet’s structure, one in which the jet curves dramatically and the most energetic light originates far from the black hole. This, Madejski said, is where theorists come in. “Our study poses a very important challenge to theorists: how would you construct a jet that could potentially be carrying energy so far from the black hole? And how could we then detect that? Taking the magnetic field lines into account is not simple. Related calculations are difficult to do analytically, and must be solved with extremely complex numerical schemes.”

Theorist Jonathan McKinney, a Stanford University Einstein Fellow and expert on the formation of magnetized jets, agrees that the results pose as many questions as they answer. “There’s been a long-time controversy about these jets – about exactly where the gamma-ray emission is coming from. This work constrains the types of jet models that are possible,” said McKinney, who is unassociated with the recent study. “From a theoretician’s point of view, I’m excited because it means we need to rethink our models.”

As theorists consider how the new observations fit models of how jets work, Hayashida, Madejski and other members of the research team will continue to gather more data. “There’s a clear need to conduct such observations across all types of light to understand this better,” said Madejski. “It takes a massive amount of coordination to accomplish this type of study, which included more than 250 scientists and data from about 20 telescopes. But it’s worth it.”

With this and future multi-wavelength studies, theorists will have new insight with which to craft models of how the universe’s biggest accelerators work. Darth Vader has been denied all access to these research results.

Sources: DOE/SLAC National Accelerator Laboratory Press Release, a paper in the 18 February, 2010 issue of Nature.

Comments on this entry are closed.

  • blueshift0_0 March 20, 2010, 6:48 PM

    Jean-
    You didn’t post the bio I posted. Why? Can’t have been because it was too long…whats-his-holiness’ rants above were far longer. And what a stew pot of nastiness his comments were. I truly can’t fathom the purpose of this comments’ section. Maybe just pure sensationalism.

    And I thought Peratt’s papers were inspired, all. But what am I? Not even a mediocre science-blogger.

  • ND March 20, 2010, 11:14 PM

    iantresman,

    What specific research do you want to see funded for studying EU/PC?

  • DrFlimmer March 21, 2010, 5:00 AM

    OH MY GOD!

    I’ve been away for one week (a nice winter-school in Switzerland about High Energy Astropyhysics :)… speakers were: Charles Dermer, Felix Aharonian, and Lars Bergström), one week of piece and without the internet and any connection to the outside world.

    Now, I’m back online, and what the hell happened here?

    This is sad. Really!

    Btw: Good to be back! ;)

  • DrFlimmer March 21, 2010, 5:01 AM

    oh….. I meant one week of PEACE

    :-D

  • Hon. Salacious B. Crumb March 21, 2010, 7:15 AM

    @ Dr Flimmer

    I wondered where you went. Yes you are right there has been a little heated ‘discussion’ here, and no doubt, your peace with some actual science-based reality must have been joyful. Crunching particles to create other particles is no doubt great fun but still so crucial to understand the hidden intricacies of Nature.

    I once heard a lecture of Prof. David McKenzie from Sydney University, who spoke of the achievements of applied plasma physics, where he talked about wonderful odd things like diamond synthesis, thin film analysis, and window glazing technologies. Here was useful science applied to everyday life, far from the early naive experimental conjectures of people from Birkeland to Alfvén – and the unfettered hero-worship by the current needlessly blindly faithful.

    There is no need to be sad though, as some of the discussion has again just exposed the void between really useful plasma physics and pseudo-plasma physics just wanting desperately to pretending to be something else that it never can be.

    So yes, I have been a bit of a naughty boy, but the absolute frustration of having to sort out the “wheat from the chaff” every damn time some plasma physics phenomena is discussed. Honestly, every time I even hear the words “plasma physics” these days, just makes me immediately think of all the bad stuff and want to strangle or wring someone’s neck.

    In the end, the most important statement I’ve said here – summing up of this mess is this story by Jean;

    “IMO, being sick of the rubbish is exactly what they are after. Pointing out their flaws and their modus operandi needs to be said – if only so the truth is balanced and expresses mainstream science. If we lose that, I believe science and technology is in real trouble. (Along with properly understanding just how things work and the principles behind it.)”

    In these views, I sure I’m not alone. The serious problem remains how do the science journalists, front-line researchers, or actual practitioners of science communicate or translate knowledge to an interested but easily influenced audience – and still differentiate themselves from the growing din of organised anti-science lobbies driven mostly by deliberately hidden agendas or other motives.

    Hopefully your Switzerland winter-school reinforced the purity in how science works instead of the mirky fog of that sometimes appears in Universe Today. If that is the case, my sympathies.

  • Hon. Salacious B. Crumb March 21, 2010, 7:23 AM

    In view of the open criticism of my some what disdainful to describe Electric Universe proponents, I have though of a new term to describe them; E.plasmamoebidae (as a group) or E.plasmamoeba (individually).

    This might solve the issue between the sensible plasma physicists and the pretend wannabes.

  • Hon. Salacious B. Crumb March 21, 2010, 7:59 AM

    @ Dr.Flimmer

    Charles Dermer’s 2009 book entitled “High Energy Radiation from Black Holes” is an absolute classic and address this very news story! I would have been great to hear him speak (he would have solved some of the issues here on the spot.)

    He says with the figure on pg.105 that;

    …with magnetic field lines formed by currents in the accretion disk (top) [and the] black-hole magnetosphere (bottom)

    Energies extracted by the black hole are by so-called Blandford–Znajek process, and this has been used to explain the energies observed by quasars. It is exciting in this story, we may be able to test this idea out, which has only be done (I think) in computer simulations.

    I recall reading an arXiv paper by Li-Xin Li; “A Toy Model for Blandford-Znajek Mechanism.” (1999), which demonstrated some basic modelling.

    His conclusion says on pg.10.;

    “From the simple model presented in the paper we have got some insight into the Blandford-Znajek mechanism. Since the electric current generating the magnetic field must reside outside the black hole and most likely resides in a disk around the black hole, as described in our thin disk model, the strength of the magnetic field at the inner edge of the disk should be bigger than that on the horizon.”

    It is as Greg Madejski says here;

    “Our study poses a very important challenge to theorists: how would you construct a jet that could potentially be carrying energy so far from the black hole.”

    Indeed. He has a point.

    [No mentions here for astrophysical jets, without things like EU dense plasma focus (DPF) or z-pinches, which as we know, are unstable. I wonder why other here don’t mention THAT?]

  • Hon. Salacious B. Crumb March 21, 2010, 8:10 AM

    @ Dr Flimmer

    You said earlier;

    “And the final question: What causes the kinks and bends of the jet?”

    I think it might be due to the feeding mechanism of the accretion disk, and the instability of the generator of the magnetic field. We know that quasars are small and are variable over periods of days or few months. This might explain these variances, which is probably tells the recent history of the accretion disk in the lines themselves. It would be interesting if such speculation were to come true, as we might understand the environment of such object. (I’ve read little about this issue in such jets.)

  • Jean Tate March 22, 2010, 7:34 AM

    blueshift0_0,

    If you can’t spot at least some of the most obvious flaws, astronomically speaking, in Peratt’s Plasma Cosmology papers yourself, a few minutes spent googling will turn up lots of detailed rebuttals, here for example, and here.

    Hon. Salacious B. Crumb,

    I have already thanked you for providing considerable background on the “Electric Universe”.

    While I can easily understand your anger, the intensity of your feelings are no justification whatsoever for using inappropriate language here, especially towards iantresman. If you want to rebut the points he makes, do so in an objective way, based on the relevant science, or ask a pointed question (as ND has done).

    Just so my meaning is clear, should you use inappropriate language again, your comments will be deleted in their entirety.

  • Hon. Salacious B. Crumb March 22, 2010, 8:36 AM

    Thanks Jean

    May I suggest you also read the story by Nancy regarding the
    The Periodic Table of Science Bloggers”

    This shows what deception others like lantresman are capable of, and how things need to be ‘corrected’ even in the mainstream.

  • Hon. Salacious B. Crumb March 22, 2010, 10:21 AM

    There is an easier solution, of course. i, and the others of the same ilk, just won’t comment at all. However, the only problem with that idea is, how many others will be fooled by the PC/EU agenda. You were, and so was David Bradley in Nancy’s story on the Periodic Table, fooled by their hidden agenda – and your supposed to be into science journalism!

    Look. We have acting passive and nice hasn’t worked Ignoring them as trolls just encouraged them. Use objective and rational thought, and you get total irrationality.* Now you say challenging them and humiliating them is out…

    What options are left, other than perhaps “leave the gate of the chicken house wide open and let the foxes in.”

    Ok problem solved. You guys fix it!

    * Read comments by OilIsMastery the Universe Today story by Nancy “Kepler’s “First Light” Images”

  • Hon. Salacious B. Crumb March 22, 2010, 10:31 AM

    Finally. If you want an example of a earlier debate, i suggest you read Nancy’s thread and comments on the Universe Today Where Are All the Sunspots? of 2nd April 2009.

    Perhaps you can now see what a absolute trial the comment threads can really be!

    Should I endlessly just “…rebut the points he makes, do so in an objective way, based on the relevant science, or ask a pointed question.” It didn’t work then. WIll it now?

    (Reading this again reminds me of all the number of people willing to take on these guys.)

  • DrFlimmer March 22, 2010, 11:38 AM

    @ HSBC

    Yes, the lectures were great, indeed. Although I thought he spoke way too much about the Fermi satellite and too less about some theories. But that’s my taste as a theoretician ;) . Others might have liked it without the theoretical stuff…. (unbelievable ;) ).

    Btw: Nice idea about the “kinks and bends”. Instabilities in the disk. Hm… I have to talk about that with my advisor, maybe there is the possibility for a PhD project hidden in there ;) . Because the latter is what I have to think about in the next few weeks….

  • Hon. Salacious B. Crumb March 23, 2010, 12:39 AM

    @DrFlimmer

    I can understand why he would of spoken mostly on Fermi, because he though it might inspire up and coming astrophysicists towards new lines of research.
    As to the kinks and bends, no doubt there is a differential across the accretion disk in the electron flows generating the fields. There would be significant differences in the field between the inner and outer disk, and even in areas away from the disk.
    Of course, it is possible other interactions like tidal distortions by planetary material or even material striking the disk. it once remember a lecturer describing the accretion disk not as a smooth disk but something like a wobbling pizza dough base being thrown in the air.

    Sounds like you will be having some fun is finding a suitable project. Good luck to you with your search!

  • Hon. Salacious B. Crumb March 23, 2010, 12:54 AM

    @ Nancy (and all)

    It might be a bit late, but there is a great general summary of jets, there is just released as another interesting arXiv article by Luigi Foschini entitled “Jets (relativistic and non) in astrophysics.”

    This is a nice summary of the issues on jets, and raises some interesting questions. I especially like the clarity of the nature of jets, some history, and something importantly about the progenitors of the magnetic fields (without the diversionary hype.).

    Highly recommended article for intermediate novices and useful to the nature of this story.

    Note: The quote that sank into my mind was on pg.5-6;

    “It is worth noting that not all the neutron stars show jets, but only those with the accretion disk. Pulsars with high magnetic field, which destroys the disk, are thus excluded, although some jet-like structures have been observed in these sources. Nevertheless, this fact is of paramount importance, because it states that the jet does not depends on the presence of a singularity, although its power is strongly affected

    The concluding paragraph (pg.7.) is equally useful;

    Also the accretion rate seems to affect the characteristics of the jets and another parameter of a certain importance is the self-rotation of the source (spin). How these parameters (mass, accretion rate, spin) determine the characteristics of the jets, which in turn is certainly linked on how these structures were born and develop, is still one of the greatest and most fascinating mysteries of the contemporary astrophysics

    Wish we had this at the beginning of this discussion!

  • Hon. Salacious B. Crumb March 23, 2010, 12:57 AM

    Sorry, for the shouting.

    Forgot the close the HTML bold. I.e. “” not “

  • DrFlimmer March 23, 2010, 11:29 AM

    Well, Fermi has the latest and important results, so of course one MUST speak about Fermi. ;)
    I just missed a little bit of theory……

    and btw: Thanks ;)

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