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A Fine Intergalactic Haze

Take a look at NGC 4565, a spiral galaxy seen edge-on. Spiral galaxies viewed at this angle often show dark dust lanes, the result of dust from dying stars mixing with interstellar gas. We’ve discussed the problem of interstellar dust in terms of objects moving at relativistic speeds between stars, but recent quasar studies are showing us that entire galaxies may expel dust to distances of several hundred thousand light years. In terms of the NGC 4565 image, that would be ten times farther than the visible edge of the galaxy.


Image: Spiral galaxies seen edge-on often show dark lanes of interstellar dust blocking light from the galaxy’s stars, as in this image of the galaxy NGC 4565. The dust is formed in the outer regions of dying stars, and it drifts off to mix with interstellar gas. Credit: Sloan Digital Sky Survey (SDSS-II).

The astronomers who did this work talk of intergalactic space being filled with a haze of fine dust particles, a haze that can be examined by analyzing light from distant quasars as it moves near foreground galaxies on its way to Earth. The colors of 100,000 quasars were studied via the Sloan Digital Sky Survey, their light examined in relation to some 20 million galaxies. The reddening of quasars from intergalactic dust draws on the fact that dust grains block blue light more effectively than red, an effect commonly seen in sunsets on Earth.

So is the reddening of quasars caused by intergalactic dust a showstopper for dark energy, that still mysterious effect seemingly responsible for the acceleration of the universe’s expansion? Evidently not — the effects are simply too subtle. Says Ryan Scranton (UC-Davis): “Our results imply that most distant supernovae are seen through a bit of haze, which may affect estimates of their distances.” No showstopper here. Scranton simply describes the dust as ‘a bit of a nuisance,’ one that has to be factored into future high precision measurements as we try to understand how dark energy is changing the cosmos.

Much depends on the result. From the paper (internal references omitted for brevity):

Light rays from distant sources carry unique information about the matter and gravitational potential along the line-of-sight. A well-known example is the signature of intervening gas clouds imprinted into spectra of background sources via absorption lines. Mass concentrations located along the path of photons can also induce gravitational lensing effects. Background sources can be magnified… and galaxy shapes can be distorted as measured through galaxy-galaxy lensing… and cosmic shear. Measuring these effects has become a powerful tool for probing the mass distribution in the Universe.

The paper is Ménard et al., “Measuring the galaxy-mass and galaxy-dust correlations through magnification and reddening,” submitted to Monthly Notices of the Royal Astronomical Society and available online.

Comments on this entry are closed.

  • Hiro March 9, 2009, 13:40

    It reminds me about The Sloan Great Wall. I think we need to do more research in this topic if we really want to colonize outside our galaxy. I’ve read several papers about these large-scale structures and they are all incomplete. I hope we have more data soon.

  • ljk March 10, 2009, 9:42

    I don’t think colonizing other galaxies is something we have to
    worry about any time soon.

  • Hiro March 10, 2009, 17:54

    I just want to know what’s going on in the GA & SCL regions. Living at the boundaries around those places is very interesting, I think. Anyway, it will take at least 100 years to colonize most of the planets and moons in our Solar System, so I know going outside our galaxy is far beyond our time.

  • James M. Essig March 10, 2009, 23:43

    Hi Folks;

    Regarding these interstellar dust lanes, perhaps within these dust lanes and gas lanes are magnetomagnetic waves that are of ultra low frequency and which can be used to propell highly charged space craft in a manner by which such magnetomagnetic waves are now being considered as mechanisms which propell protons to kinetic energies measured perhaps as high as 10 EXP 21 eV in cosmic ray decay products detection apparatus.

    Such magnetomagnetic or magnetodynamic waves, I forget the exact word used in an article I read on the subject over the past few days, would be essentially electromagnetic waves that have “unusually strong magnetic” field components and might be responsible for accelerating charged particles to 10 EXP 21 eV or even higher energies in a manner simmilar to the plasma beat wave particle accelerators which are the subject of current research efforts to build more capable cost effective particle accelerators.

    I guess the real point is that perhaps these dust lanes can be used to our advantage when we are finally ready to travel among the galaxies. However, as Paul has mentioned in one of His recent Tau Zero threads, it is never to ealy to start laying the ground work for future interstellar space travel. Going back to the moon by 2020 is going to be much fun. It is perhap by going back to the moon and installing huge arrays of optical, IR, submillimeter MW, and radio dishes on the stable hard surface of the moon where there is no atmospheric distortion that we can perhaps learn much more about the topography of large scale features within our visible universe and start the process of detailed mapping of such. There is an old saying that says something like, “You should not go anywhere without a map.”.



  • george scaglione March 11, 2009, 16:09

    ljk,you are very very probably 101% correct “colonizing other galaxies” indeed ! here we sit trying to get back to our own moon and trying then to envision our first trip to mars.as i have said before and i hope i am wrong we will be lucky to get back to our moon by the projected date of 2020,maybe even 2030,just my opinion.mars by 2050.again just my humble opinion.lol 2050 would be right in time for my 101th birthday! think i could get to be a member of the primary crew?! :) lol?? ……. and yes jim i agree with you and paul it is never too early to start laying the foundation for space travel to the stars. I JUST WISH that people would take it as seriously as do we here.even when futuristic studies are done it is a step down the correct road.it is my understanding through my studies of these subjects in general that right now at princeton university new propulsion methods are being studied.that is to say at places like the electric propulsion and plasma dynamics lab there at princeton.also a young post graduate student by the name of ashley hallock is working on pulsed inductive thrusters.i cannot say definatively but it seems this work is being funded by princeton university and the u.s. air force! sent a couple of e mails in that direction but so far have heard nothing back. intend to do more research of my own on these subjects but it all sure sounds interesting.i know from what i have already seen that ms hallock,mentioned above,recieved her b.s. in aerospace engineering in 2005 (very impressive).if anyone can help or has something to ad please post or e mail me if you like at udt109@aol.com been working in this direction since i deceided to do my own “study” of propulsion upon reading some interesting things a couple of weeks ago. end of rant guys.your friend george scaglione

  • ljk March 12, 2009, 9:22

    George, have you seen this Web site on antimatter propulsion
    at Penn State:


  • george scaglione March 12, 2009, 10:03

    ljk, thank you!!! i do not have a minute right now but later i sure intend to look into a couple of things and will now most certainly include your lead on antimatter!!!! the very best my friend, george scaglione

  • george scaglione March 12, 2009, 14:26

    ljk,well i was a little more harried today than i expected to be so i only just now got back to the work you suggested above but thanks to my trusty printer i did get alot to look into in the future when i do find the time…….so i have done thanks to you “a good days work” in spite of it all !thanks to you my friend :) george ps everybody else who may come here and see that link – have a look and please post your comments,why not?

  • george scaglione March 13, 2009, 14:43

    ljk,paul,jim,everybody…well i’m sorry if i spent too much time trying to tell you all how busy i was but today i had a very healthy chunk of time and i spent most of it looking up and taking notes from the penn st area recommended to me above and some of the great work being done today at princeton.exciting and interesting is the concept i found from the work being done by,as i have said before,ashley hallock of princetons electric propulsion and plasma dynamics lab.it has to do with pulsed inductive thrusters,or excuse the term (PIT’S).it seems that an ion thruster uses an electric or magnetic field to accelerate a propellant,usually ammonia or argon by sending a pulse of electric current through it which lasts 10 microseconds.the ions are then accelerated out into space.by the way the power of the above can be scaled up by increasing the number of pulses per second.i instinctively wonder how good that method would be on a really large scale! comments anyone?…. also,over at penn state i had a look at well,alot,to include the concept of crosing really large chunks of space as outlined in nasa’a advanced space transportation program.they would like to be able to send an unmanned craft to alpha centauri (a centauri dream?) in “only” 50 years.for that they would like to accomplish 10% of the speed of light.for this they get into subjects like antimatter.further down the page they put it this way – “only 100 milligrams of antimatter would equal the propulsive energy of the space shuttle.also they figure we could use antimatter to get to mars in a “short” time . they claim that the specific impulse involved would be something on the order of ten to the third power feet per second! guess that is it for now but comments or corrections gladly accepted.saw alot more but i have learned by now to try not to pass on every single thing i read or learn in one big mass! thank you very much one and all your friend george

  • James M. Essig March 16, 2009, 21:17

    Hi George;

    Interesting comments. Also, I would like to point out that Penn State is also doing antimatter research if my memory serves me correctly.

    Antimatter research is going be become an increasingly more interesting field. When we consider that even the proposed supersymmetric fermions of the photino, gravatino, gluinos, the winos, and the higginos should have antimatter partners, the ramifications of the profound choice of mother nature to produce matter and antimatter becomes all the more evident.

    If there could exist some method of utilizing supersymmetric antimatter particles in the future for interstellar space craft, that would indeed by just plain awesome.


    Your Friend Jim

  • george scaglione March 18, 2009, 13:20

    yes i agree with the above jim as interesting as the work being done in ion pro pulsion is anti matter just gives as plainly “more bang for the buck ” !! will have a look at the anti matter research being done at penn state also. talk to you soon george

  • ljk May 1, 2009, 11:22


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    2008, XX, 436 p. 204 illus., 20 in color., Hardcover

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    A lot of historical material which has never been published before – such as material from the Lowell Observatory in Arizona and the archives of the Royal Astronomical Society of London.

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