by Astronomers have long been confused by two strange phenomena in the heart of our galaxy. First, the gas in the central molecular zone (CMZ), a density and chaotic region near the core of the milk stay, (that is, it is electrically charged because it has lost electrons) is ionized at a surprisingly high speed.
Second, telescopes have found a mysterious glow of gamma rays with an energy of 511 kilo electron volts (KEV) (which corresponds to the energy of an electron in peace).
Interestingly, such gamma rays are created when an electron and its antimatter counter (all basic invited particles have antimax versions of themselves that are almost identical, but with opposite load), the positron, collide and annihil in a flash of light.
The causes of both effects have remained unclear despite decades of observation. In a new study published in Letters in Physical Review, however, we show that both could be associated with one of the most difficult ingredients in the universe: Dark Matter. In particular, we suggest that a new form of dark matter, which is less solid than the types that astronomers typically search for, could be the guilty.
Hidden process
The CMZ extends over almost 700 light years and contains some of the densest molecular gas in the galaxy. Over the years, scientists have found that this region is unusually ionized, which means that the hydrogen molecules there are divided into charged particles (electrons and kernels) much faster than expected.
This could be the result of sources such as cosmic rays and star light that bomb the gas. However, these alone do not seem to be able to take into account the observed levels.
The other secret, the 511KEM emission, was first observed in the 1970s, but still has no clearly identified source. Several candidates were proposed, including supernovas, massive stars, black holes and neutron stars. However, nobody completely explains the pattern or intensity of the emission.
We asked a simple question: could both phenomena be caused by the same hidden process?
Dark matter is around 85% of the matter in the universe, but does not emit light. While his gravitational effects are clear, scientists do not yet know what it consists of.
An often overlooked possibility is that dark matter particles could be very light, with masses only a few million electrons that are far lighter than a proton and still play a cosmic role. These candidates for bright dark matter are generally referred to Sub-Gev (Giga Electronvolts) dark matter particles.
Such dark matter particles can interact with their anti -particles. In our work we examined what would happen if this Hell -Dark matter particles come into contact with their own anti -particles in the galactic center and destroy each other and produce electrons and positrons.
In the dense gas of the CMZ, these low -energy particles would quickly lose energy and ionize the surrounding hydrogen molecules very efficiently by knocking out their electrons. Because the region is so dense, the particles would not travel far. Instead, they would put most of their energy on site, which corresponds quite well to the observed ionization profile.
Using detailed simulations, we found that this simple process, dark matter particles that are destroyed in electrons and positrons that can of course explain ionization rates observed in the CMZ.
It is even better that the necessary properties of dark matter, such as its mass and interaction strength, are not conflict with known restrictions from the early universe. Dark affair of this kind seems to be a serious option.
The Positron puzzle
When dark matter produces positrons in the CMZ, these particles finally become slower and finally connect to electrons in the environment, which creates gamma rays with exactly 511KEV energy. This would be a direct connection between ionization and mysterious gloss.
We found that dark matter can explain ionization, but may also replicate a certain amount of 511KEV radiation. This striking finding suggests that the two signals may come from the same source, bright dark matter.
The exact brightness of the 511KEV line depends on several factors, including how efficiently positron -bound conditions with electrons form and where exactly they destroy themselves. These details are still uncertain.
A new way of testing the invisible
Regardless of whether the 511KEV emission and the CMZ ionization have a common source, the ionization rate in the CMZ is a valuable new observation for the examination of dark matter. In particular, it offers a way to test models that affect particles with light matter that is difficult to recognize with conventional laboratory experiments.
In our study we showed that the predicted ionization profile made of dark matter about the CMZ is remarkably flat. This is important because the observed ionization is actually relatively evenly spread.
Point sources such as the black hole in the middle of the galaxy or cosmic jet sources such as supernovas (exploding stars) cannot easily explain. But a smoothly distributed dark matter that Halo can.
Our results suggest that the center of the Milky Way can provide new references to the basic nature of dark matter.
Future telescopes with better resolution can provide further information about the spatial distribution and the relationships between the 511 KEV line and the CMZ ionization rate. In the meantime, continued observations of the CMZ can help to exclude or strengthen the explanation of the dark matter.
In any case, these strange signals from the heart of the galaxy remind us that the universe is still full of surprises. Sometimes it shows the most unexpected indications of what is beyond that.
This article will be released from the conversation under a Creative Commons license. Read the original article.
Shyam Balaji receives funding from the STFC to Grant St/X000753/1. He is connected to King’s College London.
