Another blow for (fictional) Dark matter halo

Discussion in 'Physics & Math' started by Ultron, Aug 11, 2016.

  1. Ultron Registered Senior Member

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  3. PhysBang Valued Senior Member

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    Ruling out MACHOs is actually a great step forward, since we know that most of the dark matter has to be in some form other than baryonic matter.
     
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  5. paddoboy Valued Senior Member

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    Another great example of science, in this case cosmology, in progress, and of course the application of the scientific methodology.
     
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  7. The God Valued Senior Member

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    There is no such study or argument supporting what you are saying...Since Machos are mostly of baryonic matter, so your claim that we know otherwise, appears to be doubtful.
     
  8. paddoboy Valued Senior Member

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    You have missed the point entirely. Obviously, and logically, if we can rule out MACHO's as contributing to the DM requirement, we can then concentrate on WIMP's and any other possible exotic form that may contribute to the DM picture.
     
  9. paddoboy Valued Senior Member

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    NASA's Fermi mission expands its search for dark matter
    August 12, 2016

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    Top: Gamma rays (magenta lines) coming from a bright source like NGC 1275 in the Perseus galaxy cluster should form a particular type of spectrum (right). Bottom: Gamma rays convert into hypothetical axion-like particles (green dashes) and back again when they encounter magnetic fields (gray curves). The resulting gamma-ray spectrum ((lower curve at right) would show unusual steps and gaps not seen in Fermi data, which means a range of these particles cannot make up a portion of dark matter.

    Dark matter, the mysterious substance that constitutes most of the material universe, remains as elusive as ever. Although experiments on the ground and in space have yet to find a trace of dark matter, the results are helping scientists rule out some of the many theoretical possibilities. Three studies published earlier this year, using six or more years of data from NASA's Fermi Gamma-ray Space Telescope, have broadened the mission's dark matter hunt using some novel approaches.

    Read more at: http://phys.org/news/2016-08-nasa-fermi-mission-dark.html#jCp
     
  10. paddoboy Valued Senior Member

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    http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.116.161101

    Search for Spectral Irregularities due to Photon–Axionlike-Particle Oscillations with the Fermi Large Area Telescope


    ABSTRACT
    We report on the search for spectral irregularities induced by oscillations between photons and axionlike-particles (ALPs) in the γ-ray spectrum of NGC 1275, the central galaxy of the Perseus cluster. Using 6 years of Fermi Large Area Telescope data, we find no evidence for ALPs and exclude couplings above 5×10−12GeV−1 for ALP masses 0.5≲ma≲5neV at 95% confidence. The limits are competitive with the sensitivity of planned laboratory experiments, and, together with other bounds, strongly constrain the possibility that ALPs can reduce theγ-ray opacity of the Universe.

     
  11. Dr_Toad It's green! Valued Senior Member

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    Nice graphic there. TY.
     
  12. The God Valued Senior Member

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    It is not that any of these dark matter hypothesized particles has higher probability of existence. WIMP is always a no go. Do some background check on WIMP, it is as good as dead.

    Actually there is no dark matter as conceptualized, what is missing in pravelent cosmology is 'no respect for vacuum'. And these holier-than-thou bosses of GR based cosmology are stuck. They cannot bring in any concept which can revive aether, that will be great embarrassment. But one day they have to assign certain materialistic properties to what we as of now call vacuum. I am not saying give a particulate property to vacuum, for example does gluon have particulate nature ? [Thats a close example, may not be 100% fitting.]
     
  13. paddoboy Valued Senior Member

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    More empty unsupported rhetoric.
    DM is needed for many reasons as previously explained to you, and the Bullet cluster as again was pointed out to you, was amongst the first solid evidence for its existence.....far better than your empty unsupported rhetoric.



    http://arxiv.org/pdf/1006.2483v2.pdf

    Dark Matter: A Primer
    Katherine Garrett∗ and Gintaras D¯uda† Department of Physics, Creighton University, 2500 California Plaza, Omaha, NE 68178, USA

    Dark matter is one of the greatest unsolved mysteries in cosmology at the present time. About 80% of the universe’s gravitating matter is non-luminous, and its nature and distribution are for the most part unknown. In this paper, we will outline the history, astrophysical evidence, candidates, and detection methods of dark matter, with the goal to give the reader an accessible but rigorous introduction to the puzzle of dark matter. This review targets advanced students and researchers new to the field of dark matter, and includes an extensive list of references for further study.


    . CONCLUSION AND CHALLENGES
    The astrophysical and cosmological evidence for dark matter is both impressive and compelling. What is perhaps the most striking are the multiple lines of evidence which point to the need for dark matter. Elemental abundances from Big Bang Nucleosynthesis and fundamental anisotropies in the Cosmic Microwave Background Radiation both predict very similar baryon (ordinary matter) abundances, yet each describes a completely separate era in the history of the universe in which very different physical processes are occurring. Dark matter is necessary to both describe galaxies and clusters of galaxies, and is a necessary ingredient in the formation of large scale structure. It is this concordance of evidence that makes dark matter more than just a “fudge-factor”; although strange and unexpected, dark matter seems to be a fundamental and necessary component of our universe. Although the composition and nature of dark matter is still unknown, theories like Supersymmetry or Kaluza-Klein theories of extra dimensions provide solid frameworks for attempting to understand dark matter. Of all of the particle candidates for dark matter, perhaps the best motivated is the neutralino. It is a typical WIMP: electrically neutral, weakly interacting, and massive, and through statistical mechanics in the early universe we can calculate abundances for the neutralino today which are consistent with it acting as the dark matter. Other exotic candidates for dark matter exist from axions to Q-balls to WIMPzillas. However outlandish the candidate, the hunt for dark matter continues. The Large Hadron Collider at CERN will begin collisions at 3.5 TeV per beam in 2009-2010, ramping up to 7 TeV per beam most likely in 2011 and beyond, and will search for indications of supersymmetry and dark matter. Indirect searches continue to hunt for gamma rays and antimatter which might provide evidence for dark matter; the current controversy between PAMELA and ATIC and FERMI and HESS results demonstrate the advances and challenges in indirect detection. And finally, direct detection experiments continue to set more stringent limits on neutralino and WIMP scattering cross sections; these limits, as new technology is applied, are set to improve dramatically in the next decade with experiments like Super CDMS, GENIUS, and ZEPLIN IV. Dark matter, of course, is not completely understood and faces challenges. The primary challenge is that it remains undetected in the laboratory. Another tension for dark matter is that it seems to possess too much power on small scales (∼ 1 - 1000 kpc). Numerical simulations of the formation of dark matter halos were performed by Klypin et al. and show that, to explain the average velocity dispersions for the Milky Way and Andromeda, there should be five times more dark matter satellites (dwarf galaxies with a very small ordinary matter content) with circular velocity > 10-20 km/s and mass > 3×108 M within a 570 kpc radius than have been detected.92 In other words, although dark matter is crucial in forming structure, current models form too much structure. Another study, from B. Moore et al., shows that dark matter models produce more steeply rising rotation curves than we see in many low surface brightness galaxies, again suggesting that simulations produce an overabundance of dark matter.93 Of course, discrepancies on small scales may be entirely due to astrophysical processes; for example, photo-heating during reionization and/or supernova feedback particularly affect dwarf galaxies94,95. Although important to consider, these challenges faced by dark matter are dwarfed by the compelling evidence for the necessity of dark matter along with its successes in explaining our universe. What makes this field so rich and vibrant is that work and research continue, and these challenges will lead to deeper understanding in the future. Dark matter is an opportunity to learn more about the fundamental order of the universe. Dark matter provides a tantalizing glimpse beyond the highly successful Standard Model of particle physics. The discovery of neutralinos would prove the validity of supersymmetry and help bridge the “desert” between the electroweak and the Planck scales. But ultimately, we look at dark matter as a mystery, one which will hopefully inspire physics and astronomy students in and out of the classroom. As Einstein said, “The most beautiful thing we can experience is the mysterious. It is the source of all true art and all science.”
     
  14. The God Valued Senior Member

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    Paddoboy,

    You do not explain anything to anybody. You just supply links or copy paste without understanding. First read the concepts behind and don't repeat the parrotized nonsense again and again.
     
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  15. paddoboy Valued Senior Member

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    I've explained plenty to you and if you had of been listening, you would not have had as many threads moved to pseudoscience and cesspool.

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    My scientific links as always will be linked to show what nonsense you continually infest this forum with...

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    Here's some more science you seem to have an aversion to for reasons i have stated in the past.....

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    The following is a paper on the design of LZ.......

    http://arxiv.org/abs/1509.02910
    https://arxiv.org/ftp/arxiv/papers/1509/1509.02910.pdf
    ABSTRACT
    The design and performance of the LUX-ZEPLIN (LZ) detector is described as of March 2015 in this Conceptual Design Report. LZ is a second-generation dark-matter detector with the potential for unprecedented sensitivity to weakly interacting massive particles (WIMPs) of masses from a few GeV/c2 to hundreds of TeV/c2 . With total liquid xenon mass of about 10 tonnes, LZ will be the most sensitive experiment for WIMPs in this mass region by the end of the decade. This report describes in detail the design of the LZ technical systems. Expected backgrounds are quantified and the performance of the experiment is presented. The LZ detector will be located at the Sanford Underground Research Facility in South Dakota. The organization of the LZ Project and a summary of the expected cost and current schedule are given.
     
  16. Daecon Kiwi fruit Valued Senior Member

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    Stop parrotizing your own nonsense.
     
  17. The God Valued Senior Member

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    Where do you post your science content?
     
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  18. paddoboy Valued Senior Member

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    At least he has the balls to ask questions and post in the correct sections.
    Your posts and threads should all be near exclusively in cesspool.
    But again, all you need do is supply one reputable link, paper, supporting any of the gobblydook nonsensical pseudoscience that you have ever claimed over the past 12 months or so.

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    Onto the subject matter, DM is now a generally accepted part of 21st century cosmology, and is needed to explain some anomalous effects that we observe.

    In the meantime enjoy the following paper and its proposals etc, on this still rather mysterious subject.......

    http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.116.101302

    Planckian Interacting Massive Particles as Dark Matter:

    ABSTRACT

    The standard model could be self-consistent up to the Planck scale according to the present measurements of the Higgs boson mass and top quark Yukawa coupling. It is therefore possible that new physics is only coupled to the standard model through Planck suppressed higher dimensional operators. In this case the weakly interacting massive particle miracle is a mirage, and instead minimality as dictated by Occam’s razor would indicate that dark matter is related to the Planck scale, where quantum gravity is anyway expected to manifest itself. Assuming within this framework that dark matter is a Planckian interacting massive particle, we show that the most natural mass larger than 0.01Mp is already ruled out by the absence of tensor modes in the cosmic microwave background (CMB). This also indicates that we expect tensor modes in the CMB to be observed soon for this type of minimal dark matter model. Finally, we touch upon the Kaluza-Klein graviton mode as a possible realization of this scenario within UV complete models, as well as further potential signatures and peculiar properties of this type of dark matter candidate. This paradigm therefore leads to a subtle connection between quantum gravity, the physics of primordial inflation, and the nature of dark matter.
    :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::


     
  19. paddoboy Valued Senior Member

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    Let him be Daecon: Obviously he now sees his "nuisance value" to the forum as indispensable and as directed by his religious overlords and his ongoing "god of the gaps" crusade.
    Some of those that have recognised that "nuisance value" have him now on ignore.
    I prefer to keep showing him for what he is.

    Back onto science.......
    I have come across a very recent paper on DM inferring a "heavy" particle and inferring that maybe some signal could be forthcoming in any detectable primordial gravitational waves.
    Will search today and post same, in between watching Important Olympic game events.

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    Last edited: Aug 13, 2016
  20. Daecon Kiwi fruit Valued Senior Member

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    It's cute that you're so obsessed with that, let's just say that it's a reputable forum that takes a dim view of nonsense like yours, so you've probably already been banned from there.

    The question you should be asking is where don't I post pseudoscience and crackpottery with the delusion that I know it all and I'm never wrong - the answer to that is: Anywhere.

    But hey, I'm just a kid, right The God? But at least I know how gravitational lensing works.

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  21. The God Valued Senior Member

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    So Macho is gone, Wimp was never in the race, and now let's see how long this Pimp fancies us!! The above paper is total nonsense. Planck level, suppressed dimensions, Occam's razor...everything is shoved in it.
     
  22. The God Valued Senior Member

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    So you dont consider this forum as reputable ? You reserve your science contents only for reputable forums and this disreputable SF gets your trolling.....
     
  23. paddoboy Valued Senior Member

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    27,543
    A theoretical paper certainly, but no where near the stupidity shown in your own god bothering nonsensical posts/threads, that you have infested this forum with, and that have been rightly moved to the deep fringes.
     

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