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Mystery in the Perseus Cluster
- bellerocky 12y agoThis seems like a better source: http://science.nasa.gov/science-news/science-at-nasa/2014/24jul_perseuscluster/ http://science.nasa.gov/science-news/science-at-nasa/2014/24...
- WaxProlix 12y agoThanks, the writing alone on that other one was atrocious.
- houseofshards 12y agoPrecisely ! Fe XXV ? That sounds a bit like descendent from a long line of monarchs.
- guard-of-terra 12y agoNASA site spells it the same. Presumably it's how physicists call ions.
- tinco 12y agoI learned to spell ions like that in highschool, though never more than Fe III, I think.
- gus_massa 12y agoI also thought that FE XXV was a misspelling, or bad use of notation. But it's (apparently) the usual notation in spectroscopy. http://www.nist.gov/data/PDFfiles/jpcrd200.pdf http://www.nist.gov/data/PDFfiles/jpcrd200.pdf FE I is not ionized Fe (26 protons, 26 electrons, 0 net charge) FE II is ionized Fe (26 protons, 25 electrons, +1 net charge) FE III is not ionized Fe (26 protons, 24 electrons, +2 net charge) ... FE XXV has (26 protons, 2 electrons, +24 net charge) FE XXVI has (26 protons, 1 electron, +25 net charge) -- This is not the standard chemical notation. In chemistry: FE II is ionized Fe++ (26 protons, 24 electrons, +2 net charge) FE III is ionized Fe+++ (26 protons, 23 electrons, +3 net charge)
- deleted 12y ago[deleted]
- traek 12y ago> First of all, it's not necessary to use a word such as "menagerie" in any article, apparently it's being used incorrectly anyways, it means "a collection of animals". A commonly used secondary definition of menagerie is "a strange or diverse collection of people or things."
- dang 12y agoThanks. We changed to that from http://thewatchers.adorraeli.com/2014/07/25/mysterious-signal-from-the-center-of-the-perseus-cluster-unexplained-by-known-physics http://thewatchers.adorraeli.com/2014/07/25/mysterious-signa....
- pavel_lishin 12y agoWait, so there are thousands of galaxies, all of them inside a cloud of relatively dense, incredibly hot gas? And it also contains a very energetic source of energy in the middle? I'm imagining a boiling ocean, covered in volcanoes, with a nuclear bomb going off in the middle of it.
- Sharlin 12y agoWell, "relatively dense and incredibly hot gas" in this context means "still indistinguishable from vacuum without sensitive sensors, even if you were immersed in it".
- pavel_lishin 12y agoHm, I thought it said it was in the multi-million degree temperature range. I guess you can still have near-vacuum atoms at a pretty high temperature.
- Tycho 12y agoThis observation notwithstanding, if dark matter cannot be observed, isolated or detected, then why should we treat it as anything more than an arbitrary hypothesis? Why not dismiss it similar to how we dismiss the idea that God created the universe, or indeed that God is holding the cosmos together?
- deleted 12y ago[deleted]
- timClicks 12y agoI'm a layman, but my guess is that as physicists know that there isn't enough matter and energy in the universe to account for its mass, they really want to know why.
- DavidSJ 12y agoDark matter was proposed as an explanation for observations, e.g. the galaxy rotation problem. [1] Assuming the hypothesis is correct, then we have therefore already observed it (albeit indirectly, but all observations are indirect). [1] http://en.wikipedia.org/wiki/Galaxy_rotation_curve http://en.wikipedia.org/wiki/Galaxy_rotation_curve
- Tycho 12y agoIsn't that putting the cart before the horse a bit? You need to explain galaxy rotation, fine, but I could invent any arbitrary hypothesis to say why the galaxies are rotating too fast, then cite the rotation as evidence for the hypothesis. This doesn't strike me as very good science. I would want to capture some dark matter in a lab and examine its properties (or something equivalent) and then conclude that this might explain our astronomical observations.
- hrjet 12y agoSometimes you need a lab so big that you need to observe astronomical phenomena before your time runs out.
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- vesinisa 12y agoThis is exactly what drives real science. First we gather data and make sure that data is valid, then we compare it to our predictions (model), and if not all things are explained by the model, we start refining the model. In the process, our understanding of the world becomes ever more comprehensive. So in short, data not agreeing with the model is the best possible scenario.
- asuffield 12y agoYup. This is awesome. It's been a while and an awful lot of work since somebody found evidence of some new physics. The LHC has been a bit of a disappointment so far - it has yet to surprise us.
- signa11 12y agohiggs boson ?
- runiq 12y ago"It has yet to surprise us."
- asuffield 12y agoLooks like it's exactly where everybody thought it would be. Nice to confirm, but it doesn't give us a lead on any new physics.
- jerf 12y agohttp://www.theatlantic.com/technology/archive/2012/07/why-the-higgs-boson-discovery-is-disappointing-according-to-the-smartest-man-in-the-world/259468/ http://www.theatlantic.com/technology/archive/2012/07/why-th... - and while that probably isn't the best link it links to several other useful things as well. Unfortunately, we pretty much found the Higgs in the general range we expected it to be, which was in some ways the worst possible outcome, and certainly the least surprising.
- duggan 12y agoIf one of the engineers responsible for developing the technology had written this headline: "Possible Widespread Bug In X-ray Telescopes Uncovered"
- InclinedPlane 12y agoThat was indeed the original assumption when the Cosmic Microwave Background was detected. The problem with the CMB, from an observational standpoint, is that it's enormously uniform. It differs by only a few parts per million across the sky. Which means that when you perform observations with less sensitive equipment the signal tends to look like a uniform noise source. But it really does come from the sky, as we eventually figured out.
- duggan 12y agoI had conveniently forgotten about the origins of the CMB when jotting down my witty riposte. Well put!
- srean 12y agoI think Nobel committee did Ralph Alpher deep disservice. He had not only conjectured the existence of CMB radiation but also computed properties the radiation would have. The Nobel instead went to two radio engineers who happened to chance upon CMB purely by accident. George Gamow, his advisor, thought it would be funny to include Hans Bethe as a coauthor for Alpher's original research, just for the author list "Alpher, Bethe, Gamow". Bethe was not involved in anyway in that piece of research. More here http://en.wikipedia.org/wiki/Ralph_Asher_Alpher#Big_Bang_nucleosynthesis_theory http://en.wikipedia.org/wiki/Ralph_Asher_Alpher#Big_Bang_nuc... If you have not read Gamow's popular science writings.... highly recommended.
- DanielBMarkham 12y agoI agree, but as one astronomy professor put it, "Dem's the breaks"
- hvs 12y ago
- pistle 12y agoBuzzfeed style headlines. Article includes this gem: 'The menagerie of dark matter candidates that might produce this kind of line include axions, sterile neutrinos, and "moduli dark matter" that may result from the curling up of extra dimensions in string theory.' 1) Assumption of dark matter 2) String theory It's never hard to find a group of theoretical physicists willing to tag anything currently, poorly misunderstood as most likely an effect of dark matter and string theory. And, of course, this will require a new observatory.
- DCKing 12y agoThe headline perfectly summarizes that this observation is unexaplained by modern physics. You are right that associating this with dark matter and string theory is unfounded speculation, but there's nothing wrong with the headline. Also, a new observatory is a good thing. Bring it on.
- pistle 12y agoWhich is why they changed the headline. "Bring em on." - George W. Bush
- dang 12y agoWe changed the headline along with the url.
- deleted 12y ago[deleted]
- xioxox 12y agoI've worked quite a bit on this object. The Perseus cluster is one of the most interesting galaxy clusters in the sky and is the X-ray brightest (and so well studied). There's star formation, bubbles of relativistic plasma bubbles generated by the central black hole, presumably heating the surrounding gas and preventing catastrophic cooling, sound waves generated by the inflation of the bubbles, a giant nebula producing emission lines. You could give several talks about this object... Some nice pics here of the central galaxy, NGC1275: http://www-xray.ast.cam.ac.uk/papers/ngc1275/ http://www-xray.ast.cam.ac.uk/papers/ngc1275/ We'll have to wait to see if this result can be replicated by others and we'll look at the results from ASTRO-H when it launches. If you examine at the original paper (http://arxiv.org/abs/1402.2301 http://arxiv.org/abs/1402.2301), it's certainly not cut and dried dark matter emission (yet).
- jgraham 12y ago(/me waves at xioxox) It may be worth noting the significance of ASTRO-H to this kind of science (full disclaimer: it's a long time since I did any astrophysics so I am liable to get things wrong). The attraction of ASTRO-H is not just newer == better. In fact in several ways it's worse than existing X-ray satellites, for example it won't have the angular resolution of Chandra (so no pretty pictures) or the sensitivity of XMM-Newton (so bad for looking at very faint objects). Where it is designed to excel, however, is in spectral resolution, where it is about an order of magnitude better than the other observatories. This means it's going to be great at measuring the precise energy of incoming X-rays, which is essential for studying emission lines like this. If your spectral resolution is too low you'll find it difficult to detect weak lines at all because they get averaged over such a big energy range that they end up just looking like the background emission from the hot plasma in the cluster. Once you have established that there is a line in the emission, good spectral resolution is also critical to determining which models are compatible with it. There's almost certainly a lot of ideas people can dream up that will fit "a vauge bump around 3.55keV", many of which will be eliminated once you have a better idea of the shape of the line. This is the sort of science that ASTRO-H should be good at. Hopefully someone will correct me if I made any egregious errors.
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- DanielBMarkham 12y agoAnybody care to give a layman/HS explanation of why this might be dark matter? It's been a long time since High School chemistry class, but as I remember it, spectral emission lines are caused by electrons changing orbital levels and thereby releasing a photon. So dark matter has electrons? Er, would that mean that it's not dark? Why wouldn't this just mean that we've missed an orbital level somewhere?
- privong 12y agoThe authors of the study are claiming it as an emission line, but not all emission lines come from transitions of electrons. Some come from changes in quantum rotation states (e.g., some molecular transitions), rotation-vibration states (other molecular transitions), or flips in the spin direction of electrons (the famous hydrogen 21cm line). In this case, the authors have not found known lines from molecules or atoms which would correspond to this energy. The suggestion of dark energy comes from some theories where postulated dark matter particles can annihilate if they hit another dark matter particle. In these theories, the result is emission of high energy photons with an energy which is related to the mass of the individual dark matter particle. Basically E=mc^2. So it is still an emission line, but not one that arises from an election transition in an atom or molecule.
- ajross 12y agoYes, if it interacts with photons it means that it's not "dark". But the problem is that atomic physics is awfully well travelled, the chances that we've "missed an orbital" somewhere in a conventional material seems slim (or at least it does to the authors -- I'm not an expert). So a novel photon interaction in intergalactic space would be huge news even if it doesn't map directly to dark matter.
- privong 12y agoThere is lots of unexplored territory in molecular spectroscopy. The ALMA Telescope[0]—primarily operating at millimeter and sub-millimeter wavelengths, where the bulk of molecular transitions are—is likely to discover many spectral lines which have not been classified. Estimates suggest that 50–80% of the lines seen in some observations will correspond to unknown transitions of known molecules or transitions from previously unknown molecules. But the energies of molecular (rotational) transitions are generally far too low for an unknown molecular species to be a viable explanation for a spectral line in the X-rays. [0] https://en.wikipedia.org/wiki/Atacama_Large_Millimeter_Array https://en.wikipedia.org/wiki/Atacama_Large_Millimeter_Array
- jdubya 12y agoThe Perseus Cluster is probably one of the most interesting galaxy clusters I have every had the privilege of studying. Anyone interested in the universe should take a quick gander at this massive, massive scientific wonder. New physics!
- chiph 12y agoWhat, no Omicron Persei 8 or Lrrr jokes?