WIMPs

[Steve Willner]

There have been many discussions here about WIMPs and searches for
them. Today's CfA Colloquium given by Dan Hooper of Fermilab offered
a good overview of the subject. It's available at

https://youtu.be/pPs_tvDYAl4

One note to viewers: the talk was interrupted by a fire alarm about
half an hour in. It looks as though that has been edited out of the
final video, so it should not be a problem. If there's a sudden
jump, though, you'll know why.

--
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Steve Willner Phone 617-495-7123 swil...@cfa.harvard.edu
Cambridge, MA 02138 USA

[Nicolaas Vroom]

On Friday, 20 October 2017 06:50:35 UTC+2, Steve Willner wrote:
> There have been many discussions here about WIMPs and searches for
> them. Today's CfA Colloquium given by Dan Hooper of Fermilab offered
> a good overview of the subject. It's available at
>
> https://youtu.be/pPs_tvDYAl4
>

Doing a search with "annihilating dark matter" I found this:
https://fermi.gsfc.nasa.gov/science/mtgs/symposia/2014/program/14A_Hooper.pdf
"Dark matter annihilating in the galactic center"

I also found this:
https://arxiv.org/abs/1403.4495
"Dark matter Annihilation in the Universe"
Which describes this annihilation process (shortly after the Big Bang?)

The Hooper 2017 talk also discusses millisecond pulsars

A search with "millisecond pulsars dark matter" I found this:
https://futurism.com/dark-matter-hopes-dashed-fast-spinning-pulsars-blame-gamma-rays-galactic-center/

Which reads:
"New analysis by U.S. and European teams indicates that the excess of gamma
rays emanating from the center of the galaxy probably comes from pulsars,
not dark matter."

Also this:
https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.116.051102
"Strong Support for the Millisecond Pulsar Origin of the Galactic
Center GeV Excess"

This still raises the question:
Which is the best explanation that the observed galaxy rotation
curves (in general) do not match the calculated curves based on
visible (baryonic) matter?

Nicolaas Vroom

[Phillip Helbig (undress to reply)]

In article <aced71d3-f4a9-44ac...@googlegroups.com>,

Nicolaas Vroom <nicolaa...@pandora.be> writes:

> Which is the best explanation that the observed galaxy rotation
> curves (in general) do not match the calculated curves based on
> visible (baryonic) matter?

Depends on whom you ask. MOND enthusiasts will say MOND, dark-matter
enthusiasts will say dark matter.

I think that the MOND people are right when they say that conventional
dark matter requires a very unnatural distribution in order to explain
the observations. For example, there is a very tight correlation
between luminosity and velocity dispersion, but the luminosity comes
only from stars while the velocity dispersion is influenced by
dark-matter halos orders of magnitude larger in size. On the other
hand, we shouldn't be surprised that we don't know all the contents of
the universe, and while phenomenologically it works well, it is
difficult to fit MOND in with the rest of physics. Also, even MOND
enthusiasts admit that dark matter works well on cosmological scales. I
think that dark-matter enthusiasts should investigate MOND phenomenology
more.

Recently, unconventional dark matter, which behaves like standard dark
matter in a cosmological context and MOND-like on galaxy scales looks
like a promising development. Look for papers by Justin Khoury.