Dark Matter Daggers?

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AntennaGuy United States of America
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Dark Matter Daggers?

#1

Post by AntennaGuy »


* Meade 323 refractor on a manual equatorial mount.
* Celestron C6 SCT on a Twilight 1 Alt-Az mount
Prof. Barnhardt to Klaatu in The Day the Earth Stood Still: "There are several thousand questions I'd like to ask you.”
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Re: Dark Matter Daggers?

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Post by notFritzArgelander »


Somehow I missed this when it was posted.

It seems odd because it is relying on a model for cold dark matter that goes way beyond what is needed to explain the observations that seem to require DM's existence. It requires DM to form macroscopic objects. This is an unnecessary extra property that has been becoming disfavored as observations accumulate.

MACHOs (massive compact halo objects) were once thought possible. A thorough survey staring at the LMC looked for transient brightening events due gravitational lensing. Nothing much was seen, effectively ruling out MACHOs with average masses like Saturn or larger. The article provides a good argument why tabletop (several kgs) assemblages are highly unlikely, if not excluded. It says nothing relevant to DM in individual particles though.

One can see this by looking at hot dark matter, i.e. neutrinos. Several kgs rest mass of neutrinos in a tabletop sized assembly would really play havoc with a human body or the chemistry of any matter it encountered similarly to the cold dark matter under discussion in the article. However each cubic centimeter of your body has at least 300 neutrinos passing through uneventfully every second. As long as cold dark matter is in individual elementary particles, it's similarly harmless.
Scopes: Refs: Orion ST80, SV 80EDA f7, TS 102ED f11 Newts: AWB 130mm, f5, Z12 f5; Cats: VMC110L, Intes MK66,VMC200L f9.75 EPs: KK Fujiyama Orthoscopics, 2x Vixen NPLs (40-6mm) and BCOs, Baader Mark IV zooms, TV Panoptics, Delos, Plossl 32-8mm. Mixed brand Masuyama/Astroplans Binoculars: Nikon Aculon 10x50, Celestron 15x70, Baader Maxbright. Mounts: Star Seeker IV, Vixen Porta II, Celestron CG5
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Re: Dark Matter Daggers?

#3

Post by The Happy Parrot »


What happened with the xenon dark matter collaboration? This was a large xenon tank under a deep mine in Italy designed to detect dark matter. Have they presented any results?

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Re: Dark Matter Daggers?

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Post by notFritzArgelander »


The Happy Parrot wrote: Sat Mar 28, 2020 11:49 am What happened with the xenon dark matter collaboration? This was a large xenon tank under a deep mine in Italy designed to detect dark matter. Have they presented any results?

It has been through a succession of upgrades and improvements without, so far, finding a signal. The latest version XENONnT is going to be so sensitive that in some parts of the energy range the background of neutrinos from the cosmic background will hide any possible signal.

https://en.wikipedia.org/wiki/XENON

The experiment is designed to find WIMPs only. It does nothing to rule out other possible dark matter candidates.
Scopes: Refs: Orion ST80, SV 80EDA f7, TS 102ED f11 Newts: AWB 130mm, f5, Z12 f5; Cats: VMC110L, Intes MK66,VMC200L f9.75 EPs: KK Fujiyama Orthoscopics, 2x Vixen NPLs (40-6mm) and BCOs, Baader Mark IV zooms, TV Panoptics, Delos, Plossl 32-8mm. Mixed brand Masuyama/Astroplans Binoculars: Nikon Aculon 10x50, Celestron 15x70, Baader Maxbright. Mounts: Star Seeker IV, Vixen Porta II, Celestron CG5
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Re: Dark Matter Daggers?

#5

Post by The Happy Parrot »


That is really neat nFA. They seem to have a serious case of aperture fever. The tanks are getting wider and longer with each iteration to catch those faint fuzzies.

Point taken on the possibilities of WIMPs not being the only possibility for dark matter.
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Re: Dark Matter Daggers?

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Post by notFritzArgelander »


The Happy Parrot wrote: Sat Apr 18, 2020 12:42 pm That is really neat nFA. They seem to have a serious case of aperture fever. The tanks are getting wider and longer with each iteration to catch those faint fuzzies.

Point taken on the possibilities of WIMPs not being the only possibility for dark matter.
Using the aperture fever analogy. the cosmic neutrino background would be a lot like light pollution! :)
Scopes: Refs: Orion ST80, SV 80EDA f7, TS 102ED f11 Newts: AWB 130mm, f5, Z12 f5; Cats: VMC110L, Intes MK66,VMC200L f9.75 EPs: KK Fujiyama Orthoscopics, 2x Vixen NPLs (40-6mm) and BCOs, Baader Mark IV zooms, TV Panoptics, Delos, Plossl 32-8mm. Mixed brand Masuyama/Astroplans Binoculars: Nikon Aculon 10x50, Celestron 15x70, Baader Maxbright. Mounts: Star Seeker IV, Vixen Porta II, Celestron CG5
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Re: Dark Matter Daggers?

#7

Post by AntennaGuy »


Heh. You know you've come quite a long way in terms of experimental particle physics when you find that you have to deal with a pesky flood of neutrinos as background noise. I wonder how many years it will be until there are experiments in which all those pesky background gravity waves are perceived as getting in the way of the signals of real interest.
* Meade 323 refractor on a manual equatorial mount.
* Celestron C6 SCT on a Twilight 1 Alt-Az mount
Prof. Barnhardt to Klaatu in The Day the Earth Stood Still: "There are several thousand questions I'd like to ask you.”
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