One of the biggest mysteries for researchers and scientists is the formation of the Universe. Recently, the European Organization for Nuclear Research (CERN) has been trying to discover a new particle known as an axion, which can, for the first time, provide information about the events that occurred in the Universe just one second after the Big Bang.
In this article we are going to tell you everything you need to know about the axion, the particle that could explain the Big Bang.
Axions and dark matter
Initially suggested in the 1970s by physicist Roberto Peccei together with his colleague Helen Quinn, the axion is an elementary particle that emerges from a theoretical framework intended to address a question within quantum chromodynamics (QCD), the theory describing the interactions between quarks and gluons. This question belongs to the “parity conservation problem,” which states that specific characteristics must remain unchanged by nuclear interactions. The introduction of the axion serves as a mechanism to restore this symmetry.
Among the most notable features of the axion is its potential function as a component of Dark matter, which accounts for about 27% of the total mass of the universeDark matter emits no light or radioactivity, making it invisible and only observable through its gravitational influence. If axions are proven to exist, they could be abundant throughout the universe, offering a rationale for dark matter's elusive nature as extremely light and difficult-to-detect particles.
The Big Bang and axionic particles
The primordial explosion known as the Big Bang, which initiated the formation of the universe, is an event examined by numerous cosmological models and theories. It is believed that immediately after the Big Bang, a variety of particles and radiation emerged. If axions exist, they may have been generated in substantial quantities during this early phase, playing a role in the evolution of the universe.
Axion research is important not only for dark matter, but also to improve our understanding of the universe during its formative stagesSince the Big Bang produced a large variety of particles, the possible existence of axions may provide information about the historical organization of matter and energy.
What information do we have about the history of the Universe?
Today, analysis of the electromagnetic spectrum of the Cosmic Microwave Background (CMB) has allowed scientists to trace back nearly 14 billion years to the time when the Universe had cooled enough for protons and electrons to join together for the first time, which resulted in the formation of neutral hydrogen.
The photons detected in observations of the Cosmic Microwave Background (CMB) were emitted 400.000 years after the Big Bang, making it extremely difficult to determine the history of the Universe before this time.
However, a trio of British researchers has proposed a theory that indicates the possible existence of a particle known as an axion, which could have been emitted during the first second of the history of the Universe. Although this particle remains hypothetical, there are numerous reasons to believe that the axion could actually exist within the Universe.
What exactly is an axion?
Axions are theoretical fundamental particles that, although still hypothetical, may resolve certain complex questions within contemporary particle theories.
The presence of the axion would help address the issue of strong CP symmetry, which pertains to the balance between matter and antimatter. Indeed, it may provide a natural explanation for the surprising similarities in the properties of matter and antimatter, while providing insight into the predominance of matter over antimatter in the universe.
Axions may provide insight into the mysterious "dark matter," which constitutes 23% of the Universe. Research indicates that these particles represent one of the most promising candidates for contributing to the invisible matter, or dark matter, that emerged shortly after the Big Bang.
The axion and its role in the context of dark matter
Considering the possibility that dark matter may consist of axions generated in large quantities after the Big Bang, researchers are working diligently to identify axionic dark matter as soon as possible.
A paper published in Physical Review D suggests that the advancement of more sensitive instruments aimed at detecting dark matter may inadvertently lead to the discovery of another indicator of axions, known as CaB. This term denotes an axion that is analogous to the Cosmic Microwave Background (CMB) and is called the Cosmic Axion Background. However, due to the similarities in properties between CaB and dark matter axions, there is a risk that the CaB signal may be dismissed as noise in experimental settings.
For scientists, The identification of CaB would represent a double discoveryNot only would it validate the existence of the axion, but it would also offer a new relic of the early Universe to the scientific community. The method by which CaB was generated could reveal hitherto unknown facets of the formation and evolution of the Universe.
Methods for detecting an axion
The experiments conducted at CERN were aimed at detecting the axion. An experiment designed to identify the axion particle involves the use of resonant microwave cavities, which are calibrated to the mass of the axion, placed within strong magnetic fields. This methodology is currently used in the ADMX experiment at the University of Washington and has the potential to detect the axion, if dark matter consists entirely of axions.
An additional method for detecting axions involves the use of helioscopes, specifically designed to identify axions generated within the Sun. This is achieved by employing a powerful magnet paired with X-ray detectors that have exceptionally low background. While no evidence of axions has been found to date, the CAST experiment, which includes contributions from researchers at the University of Zaragoza, has overcome astrophysical limitations and opened up a previously unexplored region for exploration.