Milky Way inside a giant void? Cosmology news
Cairo: Hani Kamal El-Din
Astronomers from the UK have proposed a new explanation for the so-called “Hubble tension” – the discrepancy between measurements of the expansion rate of the Universe at different stages of its evolution. According to their hypothesis, the problem may be due to the fact that our galaxy is located inside a giant local cosmic void. The results of the study were published in the journal Monthly Notices of the Royal Astronomical Society (MNRAS).
What is the Hubble tension
The Universe has been expanding for almost 14 billion years, and the rate of this process is measured using the Hubble constant. It can be determined in two ways: from the early Universe, by studying cosmic microwave radiation (light preserved after the Big Bang), and from the modern Universe, by analyzing the speed of recession of nearby galaxies.
However, the values obtained by these methods do not coincide: data from the early Universe indicate a lower expansion rate than observations of nearby galaxies. This discrepancy is known as the “Hubble tension”.
New Hypothesis: We Are Inside a Void
In their study, the scientists proposed that our galaxy is located at the center of a huge cosmic void with a density about 20% lower than average. This region, known as the KBC void (named after astronomers Ryan Keenan, Amy Barger, and Lennox Cowie), has a scale of about a billion light years.
The lower density of the void affects the motion of matter: matter “leaks” outward, creating an additional redshift of light. This phenomenon can explain the higher expansion rate of the Universe observed in measurements of nearby galaxies.
Confirmation through simulations
The researchers simulated the motion of matter inside the void and found that their calculations match observations, including the speeds of galaxies in different parts of the Universe.
“Perhaps, to understand the Hubble tension, we should recognize that we really are living inside a giant void,” the authors of the work note.
This discovery may not only resolve the debate about the values of the Hubble constant, but also revise the ideas about the large-scale structure of the Universe.
Clarifications
The Milky Way (Galaxy) is the galaxy in which the Earth and the Solar System are located. It belongs to the type of barred spiral galaxies.
