The cloud is an almost invisible dwarf galaxy. Its brightness is 10 times fainter than that of galaxies of this type, and in various previous mappings of this part of the sky it went undetected, as if it were a ghost. Until ultra-deep, multi-color images from the Gran Telescope de Canarias (GTC) confirmed that the spot was not some kind of photographic error, but rather an extremely diffuse object.
The Cloud has many exceptional features, but the most intriguing thing is that it could not exist if the dark matter it contained was the kind we know so far. The cloud can only be explained if we open up the range of possibilities, and it may be suitable if what we are looking at is a perfect demonstration of the effect of quantum mechanics.
MAK, CC BY
Rarity
Due to the low brightness, it is very difficult to determine the distance at which the Cloud is located. Using observations from the Green Bank Telescope (GBT, in the US), we estimate that it may be about 300 million light-years away, although new observations from the Very Large Array (VLA) telescope and the William Herschel Telescope will attempt to confirm this. whether it is. the distance is correct.
Determining the exact position of the Cloud is a very important step, since the properties we measure of this galaxy depend on the distance at which it is located.
The cloud is three times more diffuse than other objects with the same number of stars. It is one-third the size of the Milky Way, but similar in mass to the small Magellanic Cloud (400 million stars). Typically, galaxies have a much higher density of stars in their interiors, which decreases rapidly as they move away from the center. However, the density of stars in the Cloud remains almost unchanged along its entire length, and this is the main oddity.
While there are several ways to explain how a galaxy could end up more spread out than when it formed, none of these scenarios can explain Cloud. That is, we don’t know how it’s possible for a galaxy with such extreme characteristics to exist, unless… Unless Cloud’s dark matter is what we still understand to be dark matter.
Challenging the current dark matter model
The universe tells us that dark matter is made up of massive particles that interact very weakly with each other. However, it is very difficult for us to study it, since it cannot be seen, it does not emit any light. Scientists have spent decades searching for this strange substance
, and we still don’t know what particles it consists of. This is one of those great cosmological unknowns that may be solved in a few decades. This explanation, that it is made of particles with little to no interaction between them, is consistent with the fact that stars and gas become concentrated as the galaxy evolves, but what happens in the Cloud is exactly the opposite. So the Cloud is an anomaly. Cosmological modeling is unable to reproduce its “extreme characteristics” even when considering different scenarios.There is no other option: we need to extend the model to other possible dark matter. To find an explanation for Nube, we will have to look to other areas.
Diffuse dark matter?
There is a very promising possibility: Cloud’s unusual properties indicate to us that the particles that make up dark matter are not massive, but quite the opposite. It is possible that they have a ridiculously small mass, representing ultra-light dark matter formed by the hypothetical axions that we are also looking for.
We would encounter diffuse dark matter or fuzzy dark matter. And from here this last explanation leads us to quantum mechanics.
Wavelengths the size of a galaxy
We could think of dark matter as quantum particles exhibiting typical wave behavior. The smaller these particles are, the larger the wave they describe. Because we’re talking about very, very, very, very small particles, unimaginably small, their wavelengths can reach the size of a galaxy.
Simulations of this type of dark matter show that this wave behavior creates a nearly flat structure at the center of the galaxy. This could explain why the Cloud’s stars are distributed the way they are.
If this were the case, Cloud’s unusual central structure would be a manifestation of the properties of this quantum particle, but on a galactic scale.
If the hypothesis were confirmed, the world of the smallest and the largest would be one. And then the Cloud will become one of the most beautiful exhibits of nature.