“Boson Clouds” Could Explain Dark Matter

The nature of dark matter stills astonishes astronomers. As the search for dark matter particles keeps on turning up nothing, it is tempting to throw away the dark matter model altogether, but indirect evidence for the stuff remains to be strong. So what is it? One team has an idea, and they have released the results of their very first search.

The conditions of dark matter imply that it cannot be regular matter. Regular matter (atoms, molecules, and so forth) easily absorbs and emits light. Even if dark matter were clouds of molecules so frigid, they emitted practically no light, these clouds would still show up by the light they soak up. They would resemble dark nebula typically seen near the galactic plane.

There are not enough of them to account for the effects of dark matter we observe. We have likewise eliminated neutrinos. They do not interact strongly with light. However, neutrinos are a form of “hot” dark matter because neutrinos move at almost the speed of light. We know that the majority of dark matter should be sluggish and consequently “cold.” If dark matter is out there, it has to be something else.

Dark matter and elementary particles

In their most recent work, the authors argue that dark matter could be constructed from particles referred to as scalar bosons. All identified matter can be put in 2 huge categories known as fermions and bosons. A particle’s category depends on a quantum property referred to as spin. Fermions such as electrons and quarks have fractional spin such as 1/2 or 3/2. Bosons such as photons have an integer spin such as 1 or 0. Any kind of particle with a spin of 0 is a scalar boson.

While it appears like a trivial difference, both types of particles behave very differently when united in large groups. Fermions can never occupy the exact same quantum state, so when you try to press them with each other, they push back. This is why white dwarfs and neutron stars exist.

Gravity attempts to push electrons or neutrons together, but the Fermi pressure is so strong that it can withstand gravity (up to a point). On the other hand, Bosons are completely pleased occupying the same state. So if you supercool a lot of bosons (such as helium-4), they can settle right into an odd quantum object called a Bose-Einstein condensate.

The only recognized scalar boson is the Higgs boson. The Higgs cannot be dark matter considering its known properties; however, some theories suggest other scalar bosons. These would certainly not interact strongly with light, only with gravity. Since light cannot substantially heat them up, in time, these scalar bosons would certainly cool and collapse into big clouds. So probably dark matter is constructed from huge diffuse clouds of scalar bosons.

How would researchers confirm this idea?

It appears that considering that scalar bosons interact gravitationally, they also interact with gravitational waves. Depending on their mass, scalar bosons may also decay by emitting gravitons. Therefore, scalar bosons can create lasting gravitational waves with a similar frequency. It is the gravitational equivalent of a slight hum.

The team observed the gravitational-wave data from LIGO and Virgo. They tried to find evidence of a gravitational hum in the 20– 600 Hz range and found nothing. The authors conclude that there are no young scalar boson clouds in our galaxy based on their work. There are additionally no old and cold scalar boson clouds within 3,000 light-years of Earth.

This research study does not entirely eliminate scalar bosons, but it strongly limits the idea. Furthermore, now that appears to be the story of dark matter. In our search to find what it is, we continue to learn what it is not.

Read the original article on Scitech Daily.

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