Milky Way-like galaxies were present in the early universe

A team of scientists led by the University of Missouri is currently using light that has traveled across space for billions of years to observe the early universe. They have recently discovered that spiral galaxies were more common in the early universe than previously believed. 

Prevalence of early spiral galaxies 

“Scientists formerly believed most spiral galaxies developed around six to seven billion years after the universe formed,” said co-author Yicheng Guo, an associate professor of astrophysics at the University of Missouri. 

“However, our study shows spiral galaxies were already prevalent as early as two billion years afterward. This means galaxy formation happened more rapidly than we previously thought.”

The discovery helps deepen our understanding of how spiral galaxies, like the Milky Way, formed over time. 

“Knowing when spiral galaxies formed in the universe has been a popular question in astronomy because it helps us understand the evolution and history of the cosmos,” said lead author Vicki Kuhn, a graduate student at the same university. 

Varying types of spiral arms 

The formation mechanisms of spiral arms vary among different types of galaxies, and this new data aids in aligning physical properties with theoretical models, creating a more comprehensive timeline of cosmic history.

“Spiral structures are present in a majority of the galaxies that we see at low redshift and are the hubs of star formation. Understanding how and when spiral galaxies first existed in the Universe has been a popular topic since their first discovery,” noted the study authors. 

“The arms of spiral galaxies can range from grand design (having well-defined arms) to multi-armed to flocculent (patchy and discontinuous arms). Different types of spiral arms are believed to have different formation histories.“

Understanding how galaxies form over time

Using the James Webb Space Telescope (JWST), the researchers found that nearly 30% of galaxies had a spiral structure around two billion years after the universe formed. This discovery updates our understanding of the universe’s origins, which was previously based on data from NASA’s Hubble Space Telescope. 

“Using advanced instruments such as JWST allows us to study more distant galaxies with greater detail than ever before,” said Professor Guo.

“A galaxy’s spiral arms are a fundamental feature used by astronomers to categorize galaxies and understand how they form over time.” 

“Even though we still have many questions about the universe’s past, analyzing this data helps us uncover additional clues and deepens our understanding of the physics that shaped the nature of our universe.”

More about spiral galaxies

Spiral galaxies are notable for their distinct and beautiful structure, characterized by a central bulge surrounded by flat, rotating disks of stars, gas, and dust. 

These disks form spiral arms that wind outward, often appearing as sweeping, luminous pathways. The arms are sites of active star formation, glowing brightly due to the presence of young, hot stars. 

Spiral galaxies, including the Milky Way, often exhibit a dynamic interplay of gravity and angular momentum, maintaining their striking spiral shape. Their varied sizes and diverse appearances make them a prominent and fascinating subject in the study of the universe.

The Milky Way

The Milky Way Galaxy is a barred spiral galaxy that contains our solar system and is estimated to be about 100,000 light-years in diameter. 

The Milky Way is composed of a central bulge, a surrounding disk of gas, dust, and stars, and an extended halo of older stars and globular clusters. The central bulge contains a supermassive black hole known as Sagittarius A*. 

Our galaxy is part of a structure known as the Local Group, which also includes the Andromeda Galaxy and the Triangulum Galaxy, among others. 

The Milky Way is constantly rotating, with stars and other materials orbiting the galactic center. It is also actively forming new stars, particularly in its spiral arms, where dense clouds of gas and dust provide the necessary conditions for star formation. 

The Milky Way is just one of billions of galaxies in the observable universe, each with its own unique structure and characteristics.

The study is published in the Astrophysical Journal Letters.

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