Is axion dark matter?
The axion has emerged in recent years as a leading particle candidate to provide the mysterious dark matter in the cosmos, as we review here for a general scientific audience.
Has the axion been found?
An international team of physicists claim they may have found evidence for a long-theorized type of subatomic particle called the axion. The axion was first suggested in the 1970s to explain discrepancies in particle physics.
How can we detect axions?
Axions or ALPs produced by astrophysical objects could be detected by terrestrial telescopes. The CERN Axion Search Telescope (CAST) at CERN, European Oragnization for Nuclear Research, was designed to detect axions produced in the Sun’s core where x-rays scatter off strong electric fields.
What is an axion particle?
The axion is a hypothetical elementary particle that has both low mass and low energy. Itwas first proposed as a hypothetical particle in 1977 as a solution to what is called the “strong CP problem” in particle physics.
Why are axions cold?
axions are non-relativistic and therefore fall within the category of CDM. (CDM). This is a zero momentum condensate and so constitutes cold dark matter. If boson particles have very light mass and hence high density, they tend to go into a single quantum state.
Are axions WIMP?
Axions are even trickier than WIMPs. They’re theorized to be extremely light—a millionth of an electronvolt or so, about a trillion times lighter than the already tiny electron—making them next to impossible to produce or study in a traditional particle physics experiment.
Why is the axion a pseudoscalar?
The axion is the pseudo-Goldstone boson associated to the breaking of the conjectured Peccei-Quinn Abelian symmetry. The axion couples to the SM gauge fields in a CP-invariant manner (e.g. aF˜F∼a →E⋅→B), which means that the axion has to be a pseudoscalar.
How do axions form?
Axions can also be produced through the decay of strings formed at the Peccei-Quinn phase transition [19,20]. Unless inflation occurs after the P-Q phase transition, string emission is thought the dominant mechanism for axion production.
Why is dark matter cold?
The cold dark matter (CDM) hypothesis—that dark matter consists of a weakly interacting particle whose velocity dispersion in the early universe was too small to erase structure on a galactic or subgalactic scale—emerged in the early 1980s and quickly became a central element of the theory of cosmic structure formation …
Can tachyons travel faster than light?
A tachyon (/ˈtækiɒn/) or tachyonic particle is a hypothetical particle that always travels faster than light. Physicists believe that faster-than-light particles cannot exist because they are not consistent with the known laws of physics.
Is dark matter subatomic?
Most modern-day astronomers think dark matter likely consists of subatomic particles with properties that are rather different from more familiar protons and neutrons. The reigning candidate for dark matter is called a Weakly Interacting Massive Particle or WIMP.
Has dark matter been created?
As such, dark matter would have been created in the Big Bang together with all other constituting elements of the universe as we see it today.
Is dark matter attractive?
But we still need to know why dark matter doesn’t form dense objects itself. It has attractive gravity, and there is no electromagnetism to push it’s particles apart.
Are MACHOs dark matter?
WIMPs and MACHOs are two of the most popular DARK MATTER candidates. They repre- sent two very different but reasonable possibilities of what the dominant component of the universe may be. It is well established that somewhere between 90% and 99% of the material in the universe is in some as yet undiscovered form.
Why do we call dark matter dark?
Dark matter is called “dark” because it does not appear to interact with the electromagnetic field, which means it does not absorb, reflect, or emit electromagnetic radiation and is, therefore, difficult to detect.
What is dark energy made up of?
These possibilities are known as massive compact halo objects, or “MACHOs”. But the most common view is that dark matter is not baryonic at all, but that it is made up of other, more exotic particles like axions or WIMPS (Weakly Interacting Massive Particles).
Are black holes dark matter?
Dark matter, which has never been directly observed, is thought to be most of the matter in the universe and act as the scaffolding upon which galaxies form and develop. On the other hand, black holes, which can be found at the centers of most galaxies, have been observed.
Can dark matter be heated?
Scientists have found evidence that dark matter can be heated up and moved around, as a result of star formation in galaxies. The findings provide the first observational evidence for the effect known as ‘dark matter heating’, and give new clues as to what makes up dark matter.
Who invented tachyon?
Tachyons were first introduced into physics by Gerald Feinberg, in his seminal paper “On the possibility of faster-than-light particles” [Phys. Rev. 159, 1089—1105 (1967)]. E = m[1−(v/c)²]−½.
Can God travel faster than light?
It seems, so far, that no object has been observed that can travel faster than the speed of light. This in itself does not say anything at all about God. It merely reinforces the knowledge that light travels very fast indeed.
Can you touch dark matter?
When we look out into the universe, we don’t know what we’re looking at for the most part. In fact, we can’t even see most of what we’re looking at – that’s because the majority of the universe is made up of mysterious, practically invisible dark matter.
Does dark matter exist on Earth?
Based on current data, Adler estimates in the October 17 Journal of Physics A that at most some 24 trillion metric tons of dark matter lies between Earth and the moon. Such a dark matter halo might explain the anomalies seen in the orbits of the Pioneer, Galileo, Cassini, Rosetta and NEAR mission spacecraft, he adds.
Are humans matter or energy?
In life, the human body comprises matter and energy. That energy is both electrical (impulses and signals) and chemical (reactions).
Is dark matter hot or cold?
Light, fast particles are known as hot dark matter; heavy, slow ones are cold dark matter; and warm dark matter falls in between. In this way of seeing things, WIMPs are cold, sterile neutrinos are warm, and relic neutrinos from the early universe are hot.
Is our universe open or closed?
With some rather large uncertainties, all methods point to the universe being open (i.e. the density parameter is less than one). But we need to remember that it is unlikely that we have detected all of the matter in the universe yet.