Dark matter does not contain certain axion-like particles

In summary, the search for spectral irregularities due to photon-axionlike-particle oscillations in the gamma-ray spectrum of NGC 1275 did not yield any evidence and excluded couplings above 5x10^-12 GeV^-1 for ALP masses between 0.5 and 5 neV with a 95% confidence level. This strongly constrains the possibility of ALPs reducing the gamma-ray opacity of the universe. Other astrophysical observations have also ruled out the existence of axions and axion-like particles, as well as sterile neutrinos and WIMPs, leaving only electromagnetically charged particles as potential candidates for dark matter.
  • #1
this was widely reported in the past, but not commented on


based on

Search for Spectral Irregularities due to Photon–Axionlike-Particle Oscillations with the Fermi Large Area Telescope
M. Ajello et al. (The Fermi-LAT Collaboration)
Phys. Rev. Lett. 116, 161101 – Published 20 April 2016

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 the γ-ray opacity of the Universe.
how strong are those bounds, how good are those results?

note they only pertain to axions as stable cold dark matter. axions could exist but are unstable and decay.

so cold dark matter hypothesis just in 2016

axion and axion-like particles ruled out by astrophysical observations

sterile neutrinos ruled out by ice cube

WIMPS large parameter space ruled out by LUX and PandaX

SUSY-WIMPS large parameter space ruled out by LUX and PandaX

WIMPS not produced nor detected by Large Hadron Collider

anything else?
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  • #2
Not too surprising. Generally speaking, only electromagnetically charged particles should have interactions with photons. This conclusions should impact any version of an axions that lacks electrical charge. (There could be higher order loops that create particle-antiparticle pairs with electric charge that interact, I suppose, but those would be highly suppressed relative to tree level interactions with axions.)

Related to Dark matter does not contain certain axion-like particles

1. What is dark matter?

Dark matter is a hypothetical form of matter that is thought to make up approximately 85% of the total matter in the universe. It does not emit or absorb light, making it invisible and difficult to detect.

2. How do scientists know that dark matter does not contain certain axion-like particles?

Scientists have been conducting experiments and observations to try and understand the nature of dark matter. So far, there is no evidence that supports the existence of axion-like particles within dark matter.

3. What are axion-like particles?

Axion-like particles are hypothetical particles that are similar to axions, a type of elementary particle that was first theorized in the 1970s. These particles are proposed to have very low mass and interact very weakly with other particles.

4. Why is it important to study dark matter?

Understanding dark matter is crucial for understanding the structure and evolution of the universe. It plays a significant role in the formation and growth of galaxies, and its properties can also shed light on the fundamental laws of physics.

5. Are there any other theories about what dark matter could be made of?

Yes, there are several different theories about the composition of dark matter. Some propose that it could be made up of WIMPs (Weakly Interacting Massive Particles), sterile neutrinos, or even primordial black holes. However, none of these theories have been conclusively proven, and the search for the true nature of dark matter continues.

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