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Space Science

Mysterious X-ray Signal Hints At Dark Matter 100

Posted by Soulskill
from the or-the-light-from-the-death-star-explosion-finally-reached-us dept.
Astronomers using the Chandra X-ray Observatory and the XMM-Newton have recorded an unusual emission of X-ray light from a remote cluster of galaxies which may turn out to be evidence of dark matter. Astronomers think dark matter constitutes 85% of the matter in the Universe, but does not emit or absorb light like “normal” matter such as protons, neutrons and electrons that make up the familiar elements observed in planets, stars, and galaxies. Because of this, scientists must use indirect methods to search for clues about dark matter. he latest results from Chandra and XMM-Newton consist of an unidentified X-ray emission line, that is, a spike of intensity at a very specific wavelength of X-ray light. Astronomers detected this emission line in the Perseus galaxy cluster using both Chandra and XMM-Newton. They also found the line in a combined study of 73 other galaxy clusters with XMM-Newton. ... The authors suggest this emission line could be a signature from the decay of a "sterile neutrino." (Abstract.) Sterile neutrinos are a hypothetical type of neutrino that is predicted to interact with normal matter only via gravity. Some scientists have proposed that sterile neutrinos may at least partially explain dark matter.
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Mysterious X-ray Signal Hints At Dark Matter

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  • Phlogiston, the luminiferous aether, the Rutherford atom, dark matter, dark energy, the Higgs field...

    Maybe one day we'll explore the idea that the geometry of space-time isn't flat, and that most of our constants aren't.
    • by CaptainLard (1902452) on Wednesday June 25, 2014 @03:31PM (#47318433)

      Phlogiston, the luminiferous aether, the Rutherford atom, dark matter, dark energy, the Higgs field... .

      Getting closer every day...

      Maybe one day we'll explore the idea that the geometry of space-time isn't flat, and that most of our constants aren't.

      Whats stopping you?

      • by Lumpy (12016)

        Money and Physics.

    • Hey, there's some suggestive evidence that our universe may be discrete and quantized around 10^-27 (and cheats to the Plank length). That's almost aether.

      Granted, we should study the skull surface shape of these scientists, just to be sure.

    • by Soft (266615)
      Bullet cluster, bitches! [calamitiesofnature.com]
    • by Livius (318358)

      Phogiston (thermal energy) and the luminiferous aether (space-time geometry) are real. It was the materials science metaphors that were wrong.

      • I'm afraid that the "liminiferous aether" was the medium on which electromagenetic waves were carried. It was disproven by the Michelson Moreley experiment, which led to a lot of _other_ fascinating theories. Phlogiston was no more "thermal energy" than vacuum is what you pour into vacuum tubes. It was what came _out_ of burning substances and was contained in them to leak out as fire.

        Please don't rewrite the history of physics and chemistry to try and invent "privatives", the measurable absence of a someth

    • Some theoretical models seem to work by admitting that there are extra dimensions hidden to our senses, like superstring theory (it has something like 11 dimensions). Very extreme, but some observed results can actually be derived by their equations. Nothing is to be discarded as too odd, I guess.
    • by Muad'Dave (255648)

      Phlogiston Paradise!!! Ruuuuby Rod!

  • by Nyder (754090) on Wednesday June 25, 2014 @02:51PM (#47318081) Journal

    Granted I know nothing about such matters, but I wondered why time couldn't be dark matter?

    • by geekoid (135745)

      Because time doesn't impact mass.

      • by TWX (665546) on Wednesday June 25, 2014 @03:01PM (#47318161)

        Because time doesn't impact mass.

        You should see my sister-in-law...

        • by PolygamousRanchKid (1290638) on Wednesday June 25, 2014 @03:38PM (#47318509)

          Because time doesn't impact mass.

          You should see my sister-in-law...

          Marriage impacts mass. Just compare the waistlines of your single and married friends, and you will see what I mean.

          At night, a bachelor goes to the refrigerator, looks at what's inside, and then goes directly to bed.

          At night, a married man goes to the bedroom, looks at what's inside, and then goes directly to the refrigerator.

          • by TWX (665546)
            I thought marriage was created by mass, at least for most Catholics...
          • by rahvin112 (446269)

            Although there is sometimes a weight gain with marriage, it's usually the kids that cause the waistline expansion.

        • by Anonymous Coward

          You should see my sister-in-law...

          I do. Don't tell your brother.

      • Because time doesn't impact mass.

        Actually, mass and time are directly related:
        http://en.wikipedia.org/wiki/G... [wikipedia.org]

        Time is not dark matter however. We understand time, and time dilatation. As crazy as it is, we have that part figured out.
        Time is another dimension, like length, width, etc... but it is treated a tad different, but this is a very deep subject, you might as well read on it from smarter people than I: http://en.wikipedia.org/wiki/S... [wikipedia.org]
        Time does not have mass, though it affects mas.

        Dark matter however behaves a lot like other matter.

    • by Jason Levine (196982) on Wednesday June 25, 2014 @03:00PM (#47318157)

      Basically, IIRC, the best models that we have to explain the Universe say the Universe should have X amount of matter in it. When we look at the Universe, though, we see only 15% of X existing. So either our models are wildly off or there is a type of matter out there that we can't currently detect (so-called "dark matter" because we can't see it). In the case of the former, it's possible, but that would toss other theories - with more firm proof for them - out as well. In the case of the latter, it's completely possible that there is sort of a self-selection bias in play. We see normal matter regularly so our detection methods have been geared towards normal matter and miss the dark stuff.

    • Re: (Score:2, Funny)

      by Anonymous Coward

      Similarly I'm thinking that length could be magnetism. We should collaborate and revolutionize physics!

    • by Russ1642 (1087959)

      Time is a four sided square universal time-cube, not dark matter.

  • by Pro923 (1447307)
    If photons with a frequency in the visible spectrum don't react with "dark matter" than why would photons with a frequency in the xray spectrum?
    • by An Ominous Coward (13324) on Wednesday June 25, 2014 @03:57PM (#47318681)

      The hypothesis is not that the X-Rays are interacting with this type of dark matter. It is that the decay of this type of dark matter generates X-Rays.

      • by drall.kj (3527169)
        I get what you are saying but.... if it can decay into a photon isn't that the same as emitting a photon? The first line quoted above is "but does not emit or absorb light like “normal” matter." If it can generate a Photon (by decay or someother means) it can't be dark. I'm not that smart but Dark Mattter/Energy thing just stinks of take a stab in the dark (no pun intended). I think some where we have some constant of the universe calculated wrong, or we are estimating the mass of the galaxie
        • by An Ominous Coward (13324) on Wednesday June 25, 2014 @05:35PM (#47319469)

          It's the ambiguity of language that's at fault here. The key to the sentence you mentioned is "like normal matter". Normal matter absorbs electromagnetic radiation, increasing its energy level, and drops back to lower energy levels by emitting electromagnetic radiation. Thus, normal matter interacts with light. This is a different physical process than the emission of light due to decay of the particle itself.

          And while we haven't pinned down dark matter by any means, it's much more than a stab in the dark. For one, there are known particles--neutrinos--that do not interact via the electromagnetic force, so the idea of unknown particles with the same property isn't unrealistic.

          Then, there are clues from many different directions that point to something consistent with matter that interacts gravitationally but not electromagnetically. These include calculations concerning the total matter in the universe, galaxy cluster formation, the rotational speed of stars on the out edge of galaxies, etc.

        • Re: (Score:2, Interesting)

          by Anonymous Coward

          Defining dark matter as having zero interaction with electromagnetism is at best a terse over-simplification and at worst just wrong. Dark matter does not strongly interact with electromagnetism, meaning that it for the most part doesn't interfere with light other than from gravity in places we think there are lots of it. But that doesn't preclude it from having rare or much harder to see interactions, such as decays, or rare interactions with high energy photons, or creating Cerenkov radiation when passi

    • by RockDoctor (15477)

      If photons with a frequency in the visible spectrum don't react with "dark matter" than why would photons with a frequency in the x-ray spectrum?

      For the same reason that if photons in the red end of the visible spectrum don't interact with this red-transmitting filter, then why would photons at the X-ray end of the visible part of the spectrum?

      Wavelength matters to absorption spectra. That's rather what makes them spectra.

  • Hey look, it's $something_we_dont_understand, and ooh, I can claim it's evidence for $todays_fad!

    Astrophysics is big, messy, complicated, and difficult to measure. We just can't send probes to other galaxies to see what's really going on. Most of the time these things have more mundane explanations. But, until we figure out why galactic rotation curves are wonky, everyone will claim everything is due to dark matter.

    • What is the best discussion of galactic rotation curves? Best for a layperson, I should say.

      • by mcelrath (8027)

        Wikipedia is usually a good reference. These two articles talk about it. It's the oldest evidence for "dark matter". Either that or it's evidence that gravity doesn't behave entirely the way described by Einstein. The latter view has fallen out of favor due to the lack of good theories adopting that viewpoint. The former has fallen into favor due to the copious selection of theories containing a particle with little or no interactions (it's easy to do). Neither of these theory-spaces has been proven t

    • by Anonymous Coward

      Hey look, it's $something_we_dont_understand, and ooh, I can claim it's evidence for $todays_fad!

      Astrophysics is big, messy, complicated, and difficult to measure. We just can't send probes to other galaxies to see what's really going on. Most of the time these things have more mundane explanations. But, until we figure out why galactic rotation curves are wonky, everyone will claim everything is due to dark matter.

      Today's fad? Dark Matter as an idea has been around for many decades (in some form since the 30s). It's supported by a massive amount of observational evidence - its not just rotational curves of galaxies. Its lensing observations and cosmic microwave background observations and velocity dispersion measurements etc. If you are going to claim that scientists don't know what they are doing, at least take the time to read the wikipedia article on Dark Matter or something similar - it would give you some id

      • by mcelrath (8027)
        Let's have some fun. [lmgtfy.com] Also remember that luminiferous aether was an idea that was around for a long time as well. Dark matter is a difficult-to-disprove fad, without any real competing ideas. That will not always be the case.
      • by rahvin112 (446269)

        I think of this like string theory. They've got an answer searching for a problem.

        Dark matter is one of those as well. They've theorized dark matter and attributed each unexplained item in astrophysics to it but have no real evidence it exists. As the other reply said to you this is not any different than the luminiferous aether that preceded it. Dark mater may or may not exist, but it would be foolish to attribute that which we can't explain to something that we can't see or measure. All those attributes o

        • The Slashdot armchair physicist brigade is out in force I see...

        • by Lord Crc (151920)

          Dark matter is one of those as well. They've theorized dark matter and attributed each unexplained item in astrophysics to it but have no real evidence it exists.

          No. You got it exactly backwards. It's entirely the opposite of string theory. String theory was born as a theoretical construct and they're trying to figure out how to make predictions with it so they can see if it matches the real world.

          When it comes to dark matter, what they have is a ton of observations which does not match the predictions of our current theories. What they see is mass being affected by something we can't see. So they've given it a label until we figure out what it is: dark matter.

          So, j

    • But, until we figure out why galactic rotation curves are wonky, everyone will claim everything is due to dark matter.

      Well, rotation curves, gravitational lensing by galaxies, missing amounts of matter needed in the beginning universe to show us what we are seeing today, and about four other separate methods of observations that are all hinting at the same thing. Thing is that this isn't a fad, it's been one of many different theories put forth and tested since these observations started popping up in the early part of the 20th century. So far, everything theory that hasn't been "matter that doesn't interact with EM radiat

      • by mcelrath (8027)
        Well yes but if I had typed all that in my original post it would not have been as pithy and interesting. I'm not just hearing about this, I've written many academic papers on it, and I have serious reservations about the idea. *sigh* back to work...
        • Can you share your alternative theory/papers? i am sure people here would be interested.

          • by RockDoctor (15477)
            It took me 30 seconds searching to find a couple of dozen papers in this general field of research, by someone called "McElrath". I know that it may seem heretical to you near-7 digiters, but some people use their real names (or in my case, profession) here, and have done for approaching two decades now.
  • by Squidlips (1206004) on Wednesday June 25, 2014 @03:53PM (#47318643)
    Why do these crackpot-darkmatter-theories-du-jour all smell like mysticism?
  • It's a flock of pigeons.

  • Basically the dark matter may be nothing more than another type of neutrino, and we finally found its calling card.

Facts are stubborn, but statistics are more pliable.

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