X-rays From Other Galaxies Could Emanate From Particles of Dark Matter 91
sciencehabit writes "X-rays of a specific wavelength emanating from the hearts of nearby galaxies and galaxy clusters could be signs of particles of dark matter decaying in space, two independent teams of astronomers report (first study, second study). If that interpretation is correct, then dark matter could consist of strange particles called sterile neutrinos that weigh about 1/100 as much as an electron."
That's "strange weird" not "strange flavor" (Score:5, Informative)
It took me a second to figure that out. Neutrinos don't participate in the strong force and don't have any flavor. (The names are charming, but kind of annoyingly ambiguous out of context.)
They sure are strange-weird if they don't even participate in the weak force, as other neutrinos do. They're barely there at all (if they ARE there at all).
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Why do you keep posting that?
Oh, I can answer that. (Score:2)
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"It took me a second to figure that out. Neutrinos don't participate in the strong force and don't have any flavor. (The names are charming, but kind of annoyingly ambiguous out of context.)"
Be careful when you say "charm" in the context of subatomic particles. (Or "strange", for that matter. I'm looking at you, OP.) You might end up saying something you did not intend.
I don't think they've named anything "weird" yet though. Still waiting for that one.
Re:That's "strange weird" not "strange flavor" (Score:4, Interesting)
I can't wait until the entire English vocabulary has a different meaning in subatomic physics. Things were better when the names were made-up.
Well, now on topic, we'd expect that any dark matter candidate is barely there at all, wouldn't we? The only problem (for me, certainly, no the theory) is that I don't understand how something with only 7kEv * c^2 of mass won't be seen already. Even if it shares no property with normal matter, I'd expect it to appear from bare energy + momentum available at accelerators*... Or are people just classifying them as normal neutrinos?
* I mean, would it be 10^-29 times as probable as a normal neutrino? Even if so, wouldn't people have seen a bunch of them?
Re:That's "strange weird" not "strange flavor" (Score:5, Informative)
I don't understand how something with only 7kEv * c^2 of mass won't be seen already. Even if it shares no property with normal matter, I'd expect it to appear from bare energy + momentum available at accelerators*... Or are people just classifying them as normal neutrinos?
Sterile neutrinos lack the weak interaction of normal neutrinos. The process that allows accelerators and nuclear processes to produce normal neutrinos is through the weak force. In the same way you can't take a photon and turn it directly into a neutrino + anti-neutrino because they don't interact with electromagnetism, you can't take "bare energy and momentum" to produce sterile neutrinos easily in accelerators. More subtle approaches look for them in accelerators, but having a light mass means you need quite a bit of precision to account for missing energy, and a situation distinguishable from say a normal neutrino. Search attempts also involve looking at neutrino oscillations closely, because of various models allowing mixing between normal and sterile neutrinos that could cause them to come up or affect neutrinos emitted from processes that can't emit a sterile neutrino directly.
Sterile Production (Score:2)
The only problem (for me, certainly, no the theory) is that I don't understand how something with only 7kEv * c^2 of mass won't be seen already.
Sterile neutrinos are usually thought of as being produced by mixing with normal neutrinos. Hence the coupling to matter is extremely weak and with such low masses it is quite easy to imagine that they would have escaped detection so far. However neutrinos are produced with velocities near the speed of light in the Big Bang whereas dark matter is slow moving (it's "Cold Dark Matter") so it seems unlikely unless there is some production mechanism which can produce them at a slower velocity. Also, not that i
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I pretty much understood the article, so obviously it was "dumbed" down to non-physicist levels so I wouldn't get to excited about the X-ray vs. Gamma ray mix-up, especially since the photons were about half the typical KVP of a dental X-ray.
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*whoosh*
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(I was hoping somebody would notice. Thank you!)
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Neutrinos don't participate in the strong force and don't have any flavor.
Quarks have both flavour, which defines what type they are, and colour, which defines how they interact with the strong force. Quark flavours are up, down, top, bottom, charm and strange; quark colours are red, green and blue.
Neutrinos do not interact with the strong force, so they don't have colour. But they do come in different varieties, which are (as for quarks) called flavours. The neutrino flavours are electron, muon and tau, corresponding to the type of charged lepton they're associated with. (Fo
Interesting Stuff (Score:4, Informative)
but before the shouting about statistical noise begins,
RTFA... it sounds plausible.
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Denver could beat Seattle......
The Meadows had forecast that very probability prior to the contest.
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Well, if you're referring to the Denver Broncos playing football against the Seattle Mariners, then yes it's a possibility.
Otherwise no.
Re: Interesting Stuff (Score:1, Flamebait)
Re: Interesting Stuff (Score:5, Interesting)
Most science fiction sounds plausible, that is why we enjoy it. We have no proof dark matter or dark energy exists, so claiming side effects is pretty stupid. Sure, it is possible but it is equally not possie. A whole segment of theoretical physicists has been working on equations that don't require dark matter or energy with promising results so far.
And just as fast as those physicists have come up with those equations, they have been ruled out. Currently, none of the equations explain the phenomenon better than dark matter (and they're often much much worse [wikipedia.org]). It's not equally as possible that dark matter exists as that it doesn't: the current evidence points to dark matter being more likely to exist than not. Tweaking equations and throwing in correction terms to force the model to fit the observations is usually a bad approach in physics (or science in general).
BTW, looking for side-effects that would result if dark matter does exist is, far from being stupid, a decent method of indirectly confirming the existence of dark matter in the first place (since observing dark matter directly is really, really hard, perhaps even impossible).
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Of course equations work better with "dark matter" -- whatever is not calculable or not explained -- it's fricken' Dark Matter. You can't see it or sense it, but it is there, wherever observation and theory don't meet up.
Now, it might be there is such a thing as Turbulence due to Gravity, or sub-quantum fluctuations in the aether. Or even that Higgs Boson, shadows from another dimension or graviton flocking. Whatever it really is -- it will be called Dark Matter, so that everyone can feel like they understo
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This is supposed to be "Science" correct? Well it's not science at this level, it's science fiction. Is it plausible and possible that there is dark energy and matter? Of course, but we have no proof. Is it equally possible that we find some other missing thing proving that there is no dark anything, and our equations were never wrong.
My point was, and is, no theory of dark anything works either. Various physicists use various numbers for both dark matter and dark energy to make models work. That is no
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Sure, it is possible but it is equally not possie.
Probably, less than equally possible.
Nonetheless, these poor bastards are postulating intelligently with scant additional evidence about a theory yet to be empirically proven.
If they lack a quality necessary for scientific breakthrough, it is not imagination.
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RTFA... it sounds plausible.
It may sound plausible, but it doesn't look plausible, at least to me.
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Really ?
I thought Dark Matter existed as asteroids ? :-)
In asteroids [vixra.org]. (Maybe.)
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Starships (Score:4, Funny)
Re:Starships (Score:5, Funny)
It's mainly those jerks driving Sports-Utility Starships. Those things are dilithium guzzlers.
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Re:Dark matter as likely as ether and phlogiston (Score:4, Informative)
So can the recently discovered prevalence of "dark worlds", the startling number of planets that are *not* in orbit around a sun, only recently revealed by our best orbital telescopes and their occasional occulusion of other stars. Given such worlds widely spread across entire galaxies of interstellar space, galaxies could easily mass 20% more than expected from pure stellar mapping, which would handily explain most of the anomalies of galactic expansion.
Astronomers working on dark matter theories aren't ignoring that, and in fact were a big push for research into that starting over a decade ago. They expected to see a lot of occlusions to account for dark matter, but did not. The lack of and limited observations of such events sets a clear upper bound on how many such bodies can be in the galaxy and it is way below what is needed to explain rotation curves. The connections you draw to galactic densities and thinking 20% more observed baryonic mass is enough to explain situations suggests you don't really have any clue of the scale of the actual situations. Not only do you need to better examine real data, but you need to more than glance at the headlines as a start.
Looks like a simple explanation is needed (Score:5, Interesting)
It's like having someone step on your foot in a dark room - you know somebody or something else is in there but you only know from one limited sense.
As for phlogiston - damn good idea to explain some reactions if you don't know there is more than one type of gas and it was associated with some useful empirical equations. Oxidation of iron didn't fit. Not long after oxygen was discovered. Phlogiston was science in action - put up an idea - test it - find where it doesn't work and then you can find another fit.
Nowhere near the same thing. We can see those with light and radio waves from the stuff behind them.
Typo (Score:2)
Phlogiston was a short-lived idea from before the discovery of oxygen. We don't know if it was taken seriously or was just a chemical shorthand to mark unusual reactions.
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By who exactly? Journalists that never did anything other than the compulsory science in school and haven't been reporting for long or someone else?
And are likely to be nothing than a blip considering the mass involved. You do know the amount that we're talking about here don't you? Not just 0.005 of the expected mass of what we can see but many orders of magnitude more. Surely you
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big brass ones. (Score:2)
sterile neutrinos that weigh about 1/100 as much as an electron.
So what you're saying is, once you sterilize a neutrino, it only weighs 1/100 as much as when it still had balls. Those aren't just big brass ones, those are big brass ones armored in the stuff they armor Ogre's with.
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Three sigma? (Score:3)
If you believe Figure 5 in this paper [arxiv.org], I have a bitcoin exchange I would like to sell you.
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Not even significant enough to justify a paper. Enough to justify further experimentation,
You seem to have things ass-backwards, since typically the criteria needed to justify further experimentation is higher than a paper, especially considering each experiment and observation in such fields gets used for as much as it can, and to make current results available so other scientists can give their input on new experiments. Depending on the exactly what you are doing, how much has previously been done on the subject, a paper can easily be justified with results less significant than one sigma to
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Three sigma. As in .001 probability that the null hypothesis is true despite our sample observation.
No, 0.001 probability that we would observe this, or worse, if the zero hypothesis were true. In order for it to tell anything about the probability of the null hypothesis being true, you need to include the probability of the null hypothesis being true before we made the observation.
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Whoever came up with that explanation for a p-value was undoubtedly well meaning but should have been gagged. It confuses more people.
The OPs definition is simpler, much more intuitive, and correct if you add "given only the data collected in the experiment." You can actually make an argument that the OPs definition is correct as is since "null hypothesis" refers to the statistical hypothesis, which is generally assumed to relate only to the current experiment.
Yes, you can't make judgements about the actu
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There is no dark matter (Score:1)
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You realize our current accepted theories of quantum mechanics have the luminiferous aether in spades, right? It's called the electron field, which permeates the entire universe and has "electrons" as energetic disturbances within it. It's joined by many other aethers, I mean fields, such as the family of quark fields, the neutrino fields and the Higgs field(s).
It's hilarious when Slashdot armchair science critics use that example.
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