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B Dark matter can be cold warm or hot

  1. Jan 13, 2017 #1


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    According to this paper https://arxiv.org/pdf/1701.03128.pdf is this a fudge factor or can we have a mixture of energies for DM.

    Abstract. Various particle physics models suggest that, besides the (nearly) cold dark matter that accounts for current observations, additional but sub-dominant dark relics might exist. These could be warm, hot, or even contribute as dark radiation. We present here a comprehensive study of two-component dark matter scenarios, where the first component is assumed to be cold, and the second is a non-cold thermal relic. Considering the cases where the non-cold dark matter species could be either a fermion or a boson, we derive consistent upper limits on the non-cold dark relic energy density for a very large range of velocity dispersions, covering the entire range from dark radiation to cold dark matter. To this end, we employ the latest Planck Cosmic Microwave Background data, the recent BOSS DR11 and other Baryon Acoustic Oscillation measurements, and also constraints on the number of Milky Way satellites, the latter of which provides a measure of the suppression of the matter power spectrum at the smallest scales due to the free-streaming of the non-cold dark matter component. We present the results on the fraction fncdm of non-cold dark matter with respect to the total dark matter for different ranges of the non-cold dark matter masses. We find that the 2σ limits for non-cold dark matter particles with masses in the range 1–10 keV are fncdm ≤ 0.29 (0.23) for fermions (bosons), and for masses in the 10–100 keV range they are fncdm ≤ 0.43 (0.45), respectively
  2. jcsd
  3. Jan 13, 2017 #2

    Vanadium 50

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    Wolram, what is the point of this?

    You keep posting these kinds of messages with zero follow through. Of your last ten (neglecting today's) you never responded to eight of them. Having us write lengthy replies only to be ignored is very annoying.
  4. Jan 13, 2017 #3


    Staff: Mentor

    The nature of dark matter is still an open area of research, so the general answer to questions of this form is "we don't know yet". Which makes them pointless for PF discussion threads. Thread closed.
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