Hints of a dark matter particle

In summary, the current SciAm article reports tentative evidence for the possible existence of sterile neutrinos. This type of neutrino is supposed to be non-interactive with other matter, making them difficult to detect. However, using two different x-ray telescopes, the authors were able to find an emission line that presumably comes from the decay of these neutrinos. If this is confirmed, it would support the idea that dark matter is made up of sterile neutrinos.
  • #1
marcus
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Tentative evidence supporting the possible existence of "sterile neutrinos" is reported in the current SciAm:
http://www.scientificamerican.com/article.cfm?id=a-whole-lot-of-nothing

If anyone can fill in details for us, or elaborate on points made in the short news article, please do.

==sample excerpt==
...

... Alexander Kusenko of the University of California, Los Angeles... and Michael Loewenstein of the NASA Goddard Space Flight Center reasoned that if sterile neutrinos really are dark matter, they would occasionally decay into ordinary matter, producing a lighter neutrino and an x-ray photon, and it would make sense to search for these x-rays wherever dark matter is found. Using the Chandra x-ray telescope, they observed a nearby dwarf galaxy thought to be rich in dark matter and found an intriguing bump of x-rays at just the right wavelength...
==endquote==

Kusenko and Lowenstein recently repeated their experiment using a different x-ray telescope--the XMM-Newton.

This type of neutrino is called "sterile" because even less apt to interact with other matter than ordinary neutrinos. Therefore even more difficult to detect. Because detection normally involves a particle undergoing some kind of reaction. In the case of sterile neutrinos (if they actually exist) detection is necessarily somewhat indirect as in the case of Kusenko Loewenstein.

The article mentioned other observations hinting indirectly at the conjectured existence of these squeaky clean neutrinos.

I couldn't find a recent journal publication about this, but here is something from a year ago by those two authors:
http://arxiv.org/abs/1001.4055
 
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Space news on Phys.org
  • #2
Interesting news! Maybe this can tell us some more?
http://arxiv.org/abs/0912.0552"[/URL]

[B]Dark Matter Search Using Chandra Observations of Willman 1, and a Spectral Feature Consistent with a Decay Line of a 5 keV Sterile Neutrino[/B]

Michael Loewenstein (UMD/CRESST/NASA-GSFC), Alexander Kusenko (UCLA/Univ. of Tokyo)
(Submitted on 3 Dec 2009 (v1), last revised 12 May 2010 (this version, v3))
Journal reference: Astrophys.J.714:652-662,2010

Abstract: We report the results of a search for an emission line from radiatively decaying dark matter in the Chandra X-ray Observatory spectrum of the ultra-faint dwarf spheroidal galaxy Willman 1. 99% confidence line flux upper limits over the 0.4-7 keV Chandra bandpass are derived and mapped to an allowed region in the sterile neutrino mass-mixing angle plane that is consistent with recent constraints from Suzaku X-ray Observatory and Chandra observations of the Ursa Minor and Draco dwarf spheroidals. A significant excess to the continuum, detected by fitting the particle-background-subtracted source spectrum, indicates the presence of a narrow emission feature with energy 2.51 +/- 0.07 (0.11) keV and flux [3.53 +/- 1.95 (2.77)] X 10^(-6) photons/cm^2/s at 68% (90%) confidence. Interpreting this as an emission line from sterile neutrino radiative decay, we derive the corresponding allowed range of sterile neutrino mass and mixing angle using two approaches. The first assumes that dark matter is solely composed of sterile neutrinos, and the second relaxes that requirement. The feature is consistent with the sterile neutrino mass of 5.0 +/- 0.2 keV and a mixing angle in a narrow range for which neutrino oscillations can produce all of the dark matter and for which sterile neutrino emission from the cooling neutron stars can explain pulsar kicks, thus bolstering both the statistical and physical significance of our measurement.[/QUOTE]


[B]EDIT[/B]
90 papers by Alexander Kusenko, many on Sterile Neutrinos & Dark Matter:
[url]http://arxiv.org/find/astro-ph/1/au:+Kusenko_A/0/1/0/all/0/1[/url]


[B]EDIT2[/B]
Here’s a good article on Sterile Neutrinos in Nature News, 17 March 2010:
[URL]http://www.nature.com/news/2010/100317/full/464334a.html"[/URL]

And here are [PLAIN]http://asd.gsfc.nasa.gov/Michael.Loewenstein/"[/URL] homepages.

[I]... Professor Alexander Kusenko seems to be a man with "high thoughts" ...[/I] :smile:

[ATTACH=full]139004[/ATTACH]
 

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  • #3
Thanks! Your links shed additional light on the topic.
 
  • #4
marcus said:
Thanks! Your links shed additional light on the topic.

You are welcome. :wink:

I’m just a 'curious layman', but one thing that 'puzzles' me is the fact that "sterile neutrinos" doesn’t interact at all with any matter or forces, except (through) gravity??

Does this mean that sterile neutrinos are very special, or does it mean that gravity is very special (and not a "member" of the other 3 fundamental interactions)...?
 
  • #5
"Sterile" neutrinos are expected to expect non-gravitationally, but by interactions outside the Standard Model.

In some speculations, sterile neutrinos interact with ordinary neutrinos by neutrino-mass-matrix terms. Thus, an electron or mu or tau neutrino oscillates into one of them as it travels.

Another type of sterile neutrino is the right-handed neutrino, predicted by several GUT's.

It would give neutrinos "Dirac masses", like the masses of charged elementary fermions. However, in the Standard Model, that would require absurdly-small Higgs interaction terms. The favorite fix is the "seesaw model", which states that right-handed neutrinos also have a Majorana mass term -- a mass term that does not mix them with left-handed ones.

For Dirac mass m and Majorana mass M, the masses and states are:

m2/M: (left) - (m/M)*(right)
M - m2/M: (right) + (m/M)*(left)

So for m ~ 10 GeV and M ~ 1012 GeV, one gets a mostly-left-handed state with a Majorana-like mass around 0.1 eV, around what is observed.

The right-handed-neutrino mass is likely a result of GUT symmetry breaking; it is close to GUT energies.


Wikipedia:
Sterile neutrino
Neutrino oscillations
Seesaw mechanism
 
  • #6
Yuri Pavlov and Andrey Grib at the Alexander Friedmann Laboratory for Theoretical Physics at St. Petersburg hypothesize that dark matter particles are about 15 times heavier than protons, and that they can decay into pairs of particles of a type that interacts with ordinary matter.

http://en.wikipedia.org/wiki/Ultra-high-energy_cosmic_ray
 

1. What is dark matter and why is it important?

Dark matter is a type of matter that does not interact with light or other forms of electromagnetic radiation, making it invisible to current detection methods. It is believed to make up about 85% of the total matter in the universe and is important because it helps explain the structure and behavior of galaxies and the universe as a whole.

2. What are the hints of a dark matter particle?

Scientists have observed that the movement of galaxies and galaxy clusters cannot be explained by the visible matter alone. This suggests the existence of an invisible form of matter, which is commonly referred to as dark matter. Additionally, there have been various indirect observations and experiments that point towards the presence of a dark matter particle.

3. How are scientists trying to detect dark matter particles?

Scientists are using a variety of methods to try and detect dark matter particles. These include experiments using particle accelerators, direct detection experiments with underground detectors, and indirect detection experiments that look for signals or effects of dark matter interactions in space.

4. What is the current status of research on dark matter particles?

Although there have been many hints and theories about the existence of dark matter particles, they have not yet been directly observed or detected. Scientists are continuing to conduct experiments and research to better understand the properties and nature of dark matter particles.

5. Could dark matter particles have any potential applications?

The study of dark matter particles could potentially lead to a better understanding of the fundamental forces and particles that make up our universe. It could also have practical applications in areas such as astrophysics, cosmology, and particle physics. However, further research and discovery is needed before any potential applications can be fully realized.

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